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Sample records for 35cl nqr frequency

  1. 35Cl NQR frequency and spin lattice relaxation time in 3,4-dichlorophenol as a function of pressure and temperature.

    PubMed

    Ramu, L; Ramesh, K P; Chandramani, R

    2013-01-01

    The pressure dependences of (35)Cl nuclear quadrupole resonance (NQR) frequency, temperature and pressure variation of spin lattice relaxation time (T(1)) were investigated in 3,4-dichlorophenol. T(1) was measured in the temperature range 77-300?K. Furthermore, the NQR frequency and T(1) for these compounds were measured as a function of pressure up to 5?kbar at 300?K. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities W(1) and W(2) for the ?m?=?±1 and ?m?=?±2 transitions were also obtained. A nonlinear variation of NQR frequency with pressure has been observed and the pressure coefficients were observed to be positive. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. An attempt is made to compare the torsional frequencies evaluated from NQR data with those obtained by IR spectra. On selecting the appropriate mode from IR spectra, a good agreement with torsional frequency obtained from NQR data is observed. The previously mentioned approach is a good illustration of the supplementary nature of the data from IR studies, in relation to NQR studies of compounds in solid state. PMID:23161529

  2. Crystal structure and 35Cl NQR of (±) ?- (trichloromethyl) -?-propiolactone

    NASA Astrophysics Data System (ADS)

    Basaran, Reha; Dou, Shi-qi; Weiss, Alarich

    1991-09-01

    The crystal structure of (±) ?- (trichloromethyl) -?-propiolactone, C 4H 3Cl 30 2, is reported ( T=294 K); space group C52hP2 l/ c, a=1002(1) pm, b=565.O(5) pm, c=1225(l) pm, ?=9397 (3)? Z=4, V=691.85(2)×10 6pm 3. A weak hydrogen bond is observed between H (C(3)) and the carbonyl oxygen 0(2). The 35Cl NQR spectrum shows three lines in the range 77? T(K)?310. At 77K the resonance frequencies are observed at 39.822(5) MHz, 38.905(5) MHz and 38.322(5) MHz.

  3. Crystal Structure and 35Cl NQR of ( — ) ?-(trichloromethyl)- ?-propiolactone. Comparison with (±) ?-(trichloromethyl)-?-propiolactone

    NASA Astrophysics Data System (ADS)

    Dou, Shi-qi; Basaran, Reha; Paulus, Helmut; Weiss, Alarich

    1993-03-01

    The crystal structure of(-)?-(trichloromethyl)-?-propiolactone at room temperature is reported, as is the 35Cl NQR spectrum in the range 77 ? T/K ? 323.5. The compound crystallizes with the space group D24-212121, Z = 8, a = 2416.0 (10) pm, b = 975.6 (4) pm, c = 595.0 (2) pm. The intramolecular distances and angles of the two crystallographically independent (-) molecules in the unit cell are equal within the limits of error. The spread of the 35Cl NQR spectrum is within 600 kHz, not changing in the temperature range covered. The crystal structure and 35Cl NQR spectrum are discussed. The results found for the (-) compound are compared with the corresponding ones reported for the (±) compound [1], and the influence of the different intramolecular interactions in the two solid states of the chemically identical compounds on the NQR spectrum is discussed.

  4. Studies of the electronic structure and biological activity of chosen 1,4-benzodiazepines by 35Cl NQR spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Bronisz, K.; Ostafin, M.; Poleshchuk, O. Kh.; Mielcarek, J.; Nogaj, B.

    2006-11-01

    Selected derivatives of 1,4-benzodiazepine: lorazepam, lormetazepam, oxazepam and temazepam, used as active substances in anxiolytic drugs, have been studied by 35Cl NQR method in order to find the correlation between electronic structure and biological activity. The 35Cl NQR resonance frequencies ( ?Q) measured at 77 K have been correlated with the following parameters characterising their biological activity: biological half-life period ( t0.5), affinity to benzodiazepine receptor (IC 50) and mean dose equivalent. The results of experimental study of some benzodiazepine derivatives by nuclear quadrupole resonance of 35Cl nuclei are compared with theoretical results based on DFT calculations which were carried out by means of Gaussian'98 W software.

  5. Detection of {sup 14}N and {sup 35}Cl in cocaine base and hydrochloride using NQR, NMR, and SQUID techniques

    SciTech Connect

    Yesinowski, J.P.; Buess, M.L.; Garroway, A.N.; Ziegeweid, M.; Pines, A. |

    1995-07-01

    Results from {sup 14}N pure NQR of cocaine in the free base form (cocaine base) yield a nuclear quadrupole coupling constant (NQCC) e{sup 2}Qq/h of 5.0229 ({+-}0.0001) MHz and an asymmetry parameter {eta} of 0.0395 ({+-}0.0001) at 295 K, with corresponding values of 5.0460 ({+-}0.0013) MHz and 0.0353 ({+-}0.0008) at 77 K. Both pure NQR (at 295-77 K) and a superconducting quantum interference device (SQUID) detector (at 4.2 K) were used to measure the very low (<1 MHz) {sup 14}N transition frequencies in cocaine hydrochloride; at 295 K the NQCC is 1.1780 ({+-}0.0014) MHz and the asymmetry parameter is 0.2632 ({+-}0.0034). Stepping the carrier frequency enables one to obtain a powder pattern without the severe intensity distortions that otherwise arise from finite pulse power. A powder pattern simulation using an NQCC value of 5.027 MHz and an asymmetry parameter {eta} of 0.2 agrees reasonably well with the experimental stepped-frequency spectrum. The use of pure NQR for providing nondestructive, quantitative, and highly specific detection of crystalline compounds is discussed, as are experimental strategies. 31 refs., 8 figs., 1 tab.

  6. Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes

    NASA Astrophysics Data System (ADS)

    Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

    2006-05-01

    Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

  7. Electron density distribution in cladribine (2-chloro-2?-deoxyadenosine) - A drug against leukemia and multiple sclerosis - Studied by multinuclear NQR spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Latosi?ska, J. N.; Latosi?ska, M.; Seliger, J.; Žagar, V.; Kazimierczuk, Z.

    2009-07-01

    2-Chloro-2'-deoxyadenosine (Cladribine) chemotherapeutic drug has been studied experimentally in solid state by 35Cl NQR and NMR-NQR double resonance and theoretically by the Density Functional Theory. Fifteen resonance frequencies on 14N have been detected and assigned to particular nitrogen sites in the 2-CdA molecule. The effects of tautomerism, regioisomerism, conformations and molecular aggregations, related to intermolecular hydrogen bond formation, on the NQR parameters have been analysed within the DFT and AIM ( Atoms in Molecules) formalism. The properties of the whole molecule, the so-called global reactivity descriptors, have been calculated for a comparison of both syn and anti conformations of 2-CdA molecule to check the effect of crystal packing on molecular conformation.

  8. Explosives detection by nuclear quadrupole resonance (NQR)

    NASA Astrophysics Data System (ADS)

    Garroway, Allen N.; Buess, Michael L.; Yesinowski, James P.; Miller, Joel B.; Krauss, Ronald A.

    1994-10-01

    Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a laboratory prototype NQR explosives detector which interrogates a volume of 300 liters (10 ft3). This paper presents abbreviated results from a demonstration of the laboratory prototype NQR explosives detector conducted at the Federal Aviation Administration Technical Center in May 1994 on RDX-based explosives.

  9. A miniaturized NQR spectrometer for a multi-channel NQR-based detection device

    NASA Astrophysics Data System (ADS)

    Beguš, Samo; Jazbinšek, Vojko; Pirnat, Janez; Trontelj, Zvonko

    2014-10-01

    A low frequency (0.5-5 MHz) battery operated sensitive pulsed NQR spectrometer with a transmitter power up to 5 W and a total mass of about 3 kg aimed at detecting 14N NQR signals, predominantly of illicit materials, was designed and assembled. This spectrometer uses a standard software defined radio (SDR) platform for the data acquisition unit. Signal processing is done with the LabView Virtual instrument on a personal computer. We successfully tested the spectrometer by measuring 14N NQR signals from aminotetrazole monohydrate (ATMH), potassium nitrate (PN), paracetamol (PCM) and trinitrotoluene (TNT). Such a spectrometer is a feasible component of a portable single or multichannel 14N NQR based detection device.

  10. A miniaturized NQR spectrometer for a multi-channel NQR-based detection device.

    PubMed

    Beguš, Samo; Jazbinšek, Vojko; Pirnat, Janez; Trontelj, Zvonko

    2014-10-01

    A low frequency (0.5-5 MHz) battery operated sensitive pulsed NQR spectrometer with a transmitter power up to 5 W and a total mass of about 3 kg aimed at detecting (14)N NQR signals, predominantly of illicit materials, was designed and assembled. This spectrometer uses a standard software defined radio (SDR) platform for the data acquisition unit. Signal processing is done with the LabView Virtual instrument on a personal computer. We successfully tested the spectrometer by measuring (14)N NQR signals from aminotetrazole monohydrate (ATMH), potassium nitrate (PN), paracetamol (PCM) and trinitrotoluene (TNT). Such a spectrometer is a feasible component of a portable single or multichannel (14)N NQR based detection device. PMID:25233110

  11. I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics

    SciTech Connect

    Ziegeweid, M.A.

    1995-11-29

    NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it is not possible to obtain well-resolved spectra in high magnetic fields. I have used a technique to observe {sup 14}N NQR resonances via their effect on neighboring protons mediated by the heteronuclear dipolar interaction to study peptides and narcotics. The sensitivity of the SQUID is not enough to measure low-frequency surface (or other low spin density) systems. The application of spin-polarized xenon has been previously used to enhance polarization in conventional NMR experiments. Because xenon only polarizes spins with which it is in contact, it is surface selective. While differences in chemical shifts between surface and bulk spins are not large, it is expected that the differences in quadrupole coupling constant should be very large due to the drastic change of the electric field gradient surrounding spins at the surface. With this in mind, I have taken preliminary steps to measure SQUID detected polarization transfer from Xe to another spin species at 4.2 K and in small magnetic fields (<50 G). In this regime, the spin-lattice relaxation of xenon is dependent on the applied magnetic field. The results of our efforts to characterize the relaxation of xenon are presented. The final section describes the solid-state variable-temperature (VT) one- and two-dimensional {sup 13}C cross polarization (CP)/magic angle spinning (MAS) NMR of Hf({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}({eta}{sup 1}-C{sub 5}H{sub 5}){sub 2}, Zr({eta}{sup 5}-C{sub 5}H{sub 5}){sub 3}({eta}{sup 1}-C{sub 5}H{sub 5}) and Sn({eta}{sup 1}-C{sub 5}H{sub 5}){sub 4}. This work was undertaken in the hope of gaining insight into the intramolecuhrr dynamics, specifically which fluxional processes exist in the solid state, by what mechanism rearrangements are occurring, and the activation energies by which these processes are governed.

  12. Pressure Dependence of the Chlorine NQR in Chloro Pyridines

    NASA Astrophysics Data System (ADS)

    Ramesh, K. P.; Ramakrishna, J.; Suresh, K. S.; Rao, C. Raghavendra

    2000-02-01

    The 35CI NQR frequency (?Q) and spin lattice relaxation time (T1 ) in 2,6-dichloropyridine, 2 amino 3,5-dichloropyridine and 6 chloro 2-pyridinol have been measured as a function of pressure up to 5.1 kbar at 300 K, and the data have been analysed to estimate the temperature coefficients of the NQR frequency at constant volume. All the three compounds show a non linear variation of the NQR frequency with pressure which can be described by a 2nd order polynomial in pressure. The rate of change of the NQR frequency with pressure is positive and decreases with increasing pressure. The spin lattice relaxation time T1, in all the three compounds shows a small increase with pressure, indicating that the relaxation is mainly due to the torsional motions.

  13. Monoanion inhibition and 35Cl nuclear magnetic resonance studies of renal dipeptidase.

    PubMed

    Ferren, L G; Ward, R L; Campbell, B J

    1975-12-01

    Kinetic analyses of monoanion inhibition and 15Cl nuclear magnetic resonance at 5.88 MHz were employed to study monoanion interactions with the zinc metalloenzyme, renal dipeptidase. The enzyme-catalyzed hydrolysis of glycyldehydrophenylalanine exhibited competitive inhibition when the reaction rate was determined in the presence of the monovalent anions fluoride, chloride, bromide, iodide, azide, nitrate, or thiocyanate or upon the addition of the divalent anion, sulfate. Competitive inhibition was produced by these anions. One anion was bound per enzyme molecule, and except in the case of fluoride all of the anions appeared to bind at the same site. Cyanide ion produced a much more effective inhibition of renal dipeptidase than the other monoanions, and it was shown that two cyanide ions were bound per enzyme molecule. An investigation of the effect of pH upon monoanion inhibition suggested that the anion inhibitors bind to the group with a pK of approximately 7.8. Complete dissociation of this group (approximately pH 8.4) eliminates the inhibitory effect of anions. The 35Cl line broadening produced by renal dipeptidase in 0.5 M NaCl solutions was 100 times more effective than that produced by equivalent concentrations of aquozinc(II). The line broadening was dependent upon the concentration of the metalloenzyme and independent of the frequency of the exciting radiation. When zinc ion was removed from the metalloenzyme by dialysis or when chloride was titrated from the metalloenzyme by cyanide, line broadening was decreased. Treatment of renal dipeptidase with saturating concentrations of the competitive inhibitor, guanosine triphosphate, in the presence of 0.5 M NaCl also produced a significant decrease in the 35Cl line width. The 35Cl line broadening produced by renal dipeptidase was shown to decrease with increasing pH through the range pH 5.8-10.8. This line-width variation with pH appeared to result from the titration of a site on the metalloprotein with an approximate pK of 7.4. Temperature studies of 35Cl line broadening by the metalloenzyme in the presence of chloride and cyanide inhibitors suggest that the fast exchange process pertains and that the dominant relaxation mechanism is quadrupolar in nature. PMID:48

  14. (35)Cl profiling using centric scan SPRITE with variable flip angle excitation.

    PubMed

    Romanenko, Konstantin V; Cano-Barrita, P F de J; Balcom, Bruce J

    2009-05-01

    An efficient MRI technique for quantitative density profiling of samples with fast spin-lattice relaxation (T(1)<5ms) is introduced. The pulse scheme is based on the 1D centric scan SPRITE technique. Strong excitation of the sample at the k-space origin improves the sensitivity with respect to the original centric scan SPRITE technique. Radio frequency pulse durations are defined so as to provide uniform excitation of the sample at every k-space point. For a particular k-space point the pulse duration is required to be less than the inverse sample bandwidth. Simulations permit one to examine distortions from ideal profile geometry due to flip angle and spin-lattice relaxation effects. The proposed technique is especially suitable for the observation of low sensitivity samples, in particular, low-gamma nuclei like (35)Cl. In some cases, this strategy permits one to reduce the number of scans, i.e. the experiment time, by a factor of 100, depending on hardware, sample length and tolerable resolution loss. The designed pulse scheme is tested on cylindrical agar gel and type 1 Portland cement paste phantoms prepared to provide (1)H and (35)Cl signals, respectively. PMID:19201634

  15. 35Cl profiling using centric scan SPRITE with variable flip angle excitation

    NASA Astrophysics Data System (ADS)

    Romanenko, Konstantin V.; Cano-Barrita, P. F. de J.; Balcom, Bruce J.

    2009-05-01

    An efficient MRI technique for quantitative density profiling of samples with fast spin-lattice relaxation ( T1 < 5 ms) is introduced. The pulse scheme is based on the 1D centric scan SPRITE technique. Strong excitation of the sample at the k-space origin improves the sensitivity with respect to the original centric scan SPRITE technique. Radio frequency pulse durations are defined so as to provide uniform excitation of the sample at every k-space point. For a particular k-space point the pulse duration is required to be less than the inverse sample bandwidth. Simulations permit one to examine distortions from ideal profile geometry due to flip angle and spin-lattice relaxation effects. The proposed technique is especially suitable for the observation of low sensitivity samples, in particular, low-? nuclei like 35Cl. In some cases, this strategy permits one to reduce the number of scans, i.e. the experiment time, by a factor of 100, depending on hardware, sample length and tolerable resolution loss. The designed pulse scheme is tested on cylindrical agar gel and type 1 Portland cement paste phantoms prepared to provide 1H and 35Cl signals, respectively.

  16. Peak Determination of ^35 Cl(n,?) Lines

    NASA Astrophysics Data System (ADS)

    Young, Patrick

    2004-10-01

    To achieve our goal of performing a stringent test of the Isobaric Multiplet Mass Equation (IMME) for the lowest T = 2 quintuplet, an accurate measurement of the mass of ^32 S in its lowest T = 2 state is needed, as the other masses of the members of the quintuplet are well known [1]. To achieve the desired precision, several calibration reactions are required including ^35 Cl(n,?). A proton beam of 1.912 MeV is incident upon a Li 2 O target to create neutrons via ^7Li(p,n). The neutrons are then moderated and absorbed by a volume of NaCl. The resulting radiation is measured with a Ge(Li) detector. Due to differences in the position of the source during calibration versus data runs, a source of mis-calibration may result from detector orientation to and distance from the source [2]. We are currently measuring the centroid shifts with respect to detector angle to see its influence upon our data collection. [1] K. Blaum, G. Audi et. al, Phys. Rev. Lett., 91, 260801, (2003) [2] R. G. Helmer, R. J. Gehrke, R. C. Greenwood, Nucl. Instr. and Meth., 123 (1975) p. 51-59.

  17. NQR study of neutral-ionic phase transition and quantum paraelectric state in organic charge-transfer complexes

    NASA Astrophysics Data System (ADS)

    Iwase, Fumitatsu; Miyagawa, Kazuya; Kanoda, Kazushi; Horiuchi, Sachio; Tokura, Yoshinori

    2008-12-01

    NQR measurements were performed for the charge-transfer complexes DMTTF-QBr nCl n-4 under ambient and hydrostatic pressures in order to understand the neutral-ionic phase transition and the quantum critical behavior. The 35Cl NQR spectrum of DMTTF-QCl 4 showed a splitting and a shift below Tc, indicating the occurrence of dimerization and charge transfer. The spin-lattice relaxation rate 1/ T1 showed a peak anomaly around Tc, reflecting the critical slowing down. The quantum paraelectric states in DMTTF-2,6-QBr 2Cl 2 and pressured DMTTF-QBr 4 were studied by the 79Br NQR. We found the microscopic evidence for the evolution of the critical fluctuations at low temperatures in the temperature dependence of spin-lattice relaxation rate.

  18. 133Cs and 35Cl NMR spectroscopy and molecular dynamics modeling of Cs + and Cl - complexation with natural organic matter

    NASA Astrophysics Data System (ADS)

    Xu, Xiang; Kalinichev, Andrey G.; James Kirkpatrick, R.

    2006-09-01

    Interaction of dissolved aqueous species with natural organic matter (NOM) is thought to be important in sequestering some species and enhancing the transport of others, but little is known about these interactions on a molecular scale. This paper describes a combined experimental 133Cs and 35Cl nuclear magnetic resonance (NMR) and computational molecular dynamics (MD) modeling study of the interaction of Cs + and Cl - with Suwannee River NOM. The results provide a detailed picture of the molecular-scale structure and dynamics of these interactions. Individual NOM molecules are typically hundreds to thousands of Daltons in weight, and on the molecular scale their interaction with small dissolved species can be investigated in ways similar to those used to study the interaction of dissolved aqueous species with mineral surfaces. As for such surface interactions, understanding both the structural environments and the dynamics over a wide range of frequencies is essential. The NMR results show that Cs + is associated with NOM at pH values from 3.4 ± 0.5 (unbuffered Suwannee River NOM solution) to 9.0 ± 0.5. The extent of interaction increases with decreasing CsCl concentration at constant pH. It also decreases with increasing pH at constant CsCl concentration due to pH-dependent negative structural charge development on the NOM caused by progressive deprotonation of carboxylic and phenolic groups. The presence of NOM has little effect on the 133Cs chemical shifts, demonstrating that its local coordination environment does not change significantly due to interaction with the NOM. Narrow, solution-like line widths indicate rapid exchange of Cs + between the NOM and bulk solution at frequencies of >10 2 Hz. The MD simulations support these results and show that Cs + is associated with the NOM principally as outer sphere complexes and that this interaction does not reduce the Cs + diffusion coefficient sufficiently to cause NMR line broadening. The 35Cl NMR data and the MD results are consistent in demonstrating that there is no significant complexation between Cl - and NOM in the pH range investigated, consistent with negative structural charge on the NOM.

  19. Fission fragment mass distributions in 35Cl+Sm,154144 reactions

    NASA Astrophysics Data System (ADS)

    Tripathi, R.; Sodaye, S.; Sudarshan, K.; Nayak, B. K.; Jhingan, A.; Pujari, P. K.; Mahata, K.; Santra, S.; Saxena, A.; Mirgule, E. T.; Thomas, R. G.

    2015-08-01

    Background: A new type of asymmetric fission was observed in ? -delayed fission of 180Tl [Phys. Rev. Lett. 105, 252502 (2010), 10.1103/PhysRevLett.105.252502] as symmetric mass distribution would be expected based on conventional shell effects leading to the formation of N =50 fragments. Following this observation, theoretical calculations were carried out which predict asymmetric mass distribution for several mercury isotopes around mass region of ˜180 at low and moderate excitation energies [Moller, Randrup, and Sierk, Phys. Rev. C 85, 024306 (2012), 10.1103/PhysRevC.85.024306; Andreev, Adamian, and Antonenko, Phys. Rev. C 86, 044315 (2012), 10.1103/PhysRevC.86.044315]. Studies on fission fragment mass distribution are required in this mass region to investigate this newly observed phenomenon. Purpose: The fission fragment mass distributions have been measured in 35Cl+Sm,154144 reactions at Elab=152.5 ,156.1 ,and 163.7 MeV populating compound nuclei in the mass region of ˜180 with variable excitation energy and neutron number to investigate the nature of mass distribution. Method: The fission fragment mass distribution has been obtained by measuring the "time of flight (TOF)" of fragments with respect to the beam pulse using two multiwire proportional counters placed at ?lab=±65 .5? with respect to the beam direction. From the TOF of fragments, their velocities were determined, which were used to obtain mass distribution taking the compound nucleus as the fissioning system. Results: For both systems, mass distributions, although, appear to be symmetric, could not be fitted well by a single Gaussian. The deviation from a single Gaussian fit is more pronounced for the 35Cl+144Sm reaction. A clear flat top mass distribution has been observed for the 35Cl+144Sm reaction at the lowest beam energy. The mass distribution is very similar to that observed in the 40Ca+142Nd reaction, which populated a similar compound nucleus, but for the pronounced dip in the symmetric region [Phys. Rev. C 91, 064605 (2015), 10.1103/PhysRevC.91.064605]. Conclusions: The present study shows that the mass distribution deviates from that expected on the basis of a pure liquid drop model in the mass region of ˜180, indicating a contribution from asymmetric fission. The contribution from asymmetric fission is more pronounced for the 35Cl+144Sm reaction as evident from the large deviation of the fission fragment mass distribution from the single Gaussian fit. This is consistent with the observation of an asymmetric component in the 40Ca+142Nd reaction in a recent study [Phys. Rev. C 91, 064605 (2015), 10.1103/PhysRevC.91.064605]. The contribution from asymmetric component is also consistent with the theoretical predictions by Moller et al. [Phys. Rev. C 85, 024306 (2012)], 10.1103/PhysRevC.85.024306, although the magnitude of the effect appears to be smaller.

  20. Methyl quantum tunneling and nitrogen-14 NQR NMR studies using a SQUID magnetic resonance spectrometer

    SciTech Connect

    Black, B.E. |

    1993-07-01

    Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) techniques have been very successful in obtaining molecular conformation and dynamics information. Unfortunately, standard NMR and NQR spectrometers are unable to adequately detect resonances below a few megahertz due to the frequency dependent sensitivity of their Faraday coil detectors. For this reason a new spectrometer with a dc SQUID (Superconducting Quantum Interference Device) detector, which has no such frequency dependence, has been developed. Previously, this spectrometer was used to observe {sup 11}B and {sup 27}Al NQR resonances. The scope of this study was increased to include {sup 23}Na, {sup 51}V, and {sup 55}Mn NQR transitions. Also, a technique was presented to observe {sup 14}N NQR resonances through cross relaxation of the nitrogen polarization to adjacent proton spins. When the proton Zeeman splitting matches one nitrogen quadrupoler transition the remaining two {sup 14}N transitions can be detected by sweeping a saturating rf field through resonance. Additionally, simultaneous excitation of two nitrogen resonances provides signal enhancement which helps to connect transitions from the same site. In this way, nitrogen-14 resonances were observed in several amino acids and polypeptides. This spectrometer has also been useful in the direct detection of methyl quantum tunneling splittings at 4.2 K. Tunneling, frequencies of a homologous series of carboxylic acids were measured and for solids with equivalent crystal structures, an exponential correlation between the tunneling frequency and the enthalpy of fusion is observed. This correlation provides information about the contribution of intermolecular interactions to the energy barrier for methyl rotation.

  1. A measurement of parity-violating gamma-ray asymmetries in polarized cold neutron capture on 35Cl, 113Cd, and 139La

    E-print Network

    G. S. Mitchell; C. S. Blessinger; J. D. Bowman; T. E. Chupp; K. P. Coulter; M. T. W. Gericke; G. L. Jones; M. B. Leuschner; H. Nann; S. A. Page; S. I. Penttila; T. B. Smith; W. M. Snow; W. S. Wilburn

    2004-01-08

    An apparatus for measuring parity-violating asymmetries in gamma-ray emission following polarized cold neutron capture was constructed as a 1/10th scale test of the design for the forthcoming n+p->d+gamma experiment at LANSCE. The elements of the polarized neutron beam, including a polarized 3He neutron spin filter and a radio frequency neutron spin rotator, are described. Using CsI(Tl) detectors and photodiode current mode readout, measurements were made of asymmetries in gamma-ray emission following neutron capture on 35Cl, 113Cd, and 139La targets. Upper limits on the parity-allowed asymmetry $s_n \\cdot (k_{\\gamma} \\times k_n)$ were set at the level of 7 x 10^-6 for all three targets. Parity-violating asymmetries $s_n \\cdot k_{\\gamma}$ were observed in 35Cl, A_gamma = (-29.1 +- 6.7) x 10^-6, and 139La, A_gamma = (-15.5 +- 7.1) x 10^-6, values consistent with previous measurements.

  2. 93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20

    NASA Astrophysics Data System (ADS)

    Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

    2015-03-01

    We report a study of 93Nb- and 27Al-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a praseodymium based compound PrNb2Al20. The observed NMR line at around 3 T and 30 K shows a superposition of typical powder patterns of one Nb signal and at least two Al signals. 93Nb-NMR line could be reproduced by using the previously reported NQR frequency ?Q ? 1.8MHz and asymmetry parameter ? ? 0 [Kubo T et al 2014 JPS Conf. Proc. 3 012031]. From 27Al-NMR/NQR, NQR parameters are obtained to be ?Q,A ? 1.53 MHz, and ?A ? 0.20 for the site A, and ?Q,B ? 2.28 MHz, and ?B ? 0.17 for the site B. By comparing this result with the previous 27Al-NMR study of PrT2Al20 (T = Ti, V) [Tokunaga Y et al 2013 Phys. Rev. B 88 085124], these two Al site are assigned to the two of three crystallographycally inequivalent Al sites.

  3. 81Br NQR and crystal structure of 4-bromopyridinium pentabromoantimonate(III); 3c-4e bonding and NQR trans influence

    NASA Astrophysics Data System (ADS)

    Terao, Hiromitsu; Ninomiya, Seiko; Hashimoto, Masao; Eda, Kazuo

    2010-02-01

    The crystal structure of (4-BrC 5H 4NH) 2SbBr 5 was determined by a single crystal X-ray diffraction at 193 K. The crystals belong to the triclinic system (P1¯) with a = 9.1861(19) Å, b = 10.622(2) Å, c = 10.703(2) Å, ? = 99.665(3)°, ? = 97.393(3)°, ? = 108.539(3)°, and Z = 2. There exists an anion dimer Sb 2Br 104- in the crystal structure which consists of an edge-sharing between two SbBr 6 octahedra. The inversion center situated at the center of the shared-edge of the dimer relates two asymmetric units, which consist of a SbBr 52- moiety and two nonequivalent cations. Each cation is bound to the apical Br atoms of Sb 2Br 104- through N-H…Br hydrogen bonds. Seven 81Br NQR resonance lines including those for two Br atoms in the nonequivalent cations have been observed in the temperature range of 77 to ca. 360 K in accordance with the crystal structure. The frequencies of each of the respective pairs of NQR lines for the apical Br and for the equatorial Br atoms showed unusual positive temperature dependence with almost linear changes. For these curves, the other lines of pairs showed symmetrical temperature dependence, maintaining the center of mass almost constant in frequency. These observations may indicate the existence of NQR trans influence which were manifested through the occurrence of substantial electronic redistributions in the 3c-4e (Br-Sb-Br) bonds with temperature changes.

  4. New Accurate Wavenumbers of H35Cl^+ and H37Cl^+ Rovibrational Transitions in the v=0-1 Band of the ^2? State.

    NASA Astrophysics Data System (ADS)

    Domenech, Jose Luis; Cueto, Maite; Herrero, Victor Jose; Tanarro, Isabel; Cernicharo, Jose; Drouin, Brian

    2015-06-01

    HCl^+ is a key intermediate in the interstellar chemistry of chlorine. It has been recently identified in space from Herschel's spectra and it has also been detected in the laboratory through its optical emission, infrared and mm-wave spectra. Now that Hershchel is decomissioned, further astrophysical studies on this radical ion will likely rely on ground-based observations in the mid-infrared. We have used a difference frequency laser spectrometer coupled to a hollow cathode discharge to measure the absorption spectrum of H35Cl^+ and H37Cl^+ in the v=0-1 band of the ^2? state with Dopppler limited resolution. The accuracy of the individual measurements (˜ 10 MHz (3?)) relies on a solid state wavemeter referenced to an iodine-stabilized Ar^+ laser. The new data are being fit using the CALPGM software from JPL, and the current status will be presented. M. De Luca et al., Astrophys. J. Lett. 751, L37 (2012) W. D. Sheasley and C. W. Mathews, J. Mol. Spectrosc. 47, 420 (1973) P. B. Davies, P. A. Hamilton, B. A. Johnson, Mol. Phys. 57, 217 (1986) H. Gupta, B. J. Drouin, and J. C. Pearson, Astrophys. J. Lett. 751, L37 (2012)

  5. Prediction of P-branch emission spectral lines of NaF and 63Cu35Cl molecules

    NASA Astrophysics Data System (ADS)

    Jiang, Yonghong; Sun, Weiguo; Zhang, Yi; Fu, Jia; Fan, Qunchao; Li, Huidong; Feng, Hao

    2016-01-01

    The analytical formula derived by Sun et al. in 2011 and used to predict the rotational lines for rovibrational diatomic systems is improved in this study. The new formula is obtained by adding a higher order spectral term H? that is neglected in our previous expression. A physical requirement is also added to the converging process to minimize the possible error of the predicted rotational line. All these are applied to study some rovibrational transition systems of 63Cu35Cl and NaF molecules. The results indicate that the accuracy of the P-branch rotational lines predicted by this new formula is about one order of magnitude better than the results obtained using the previous formula, and that both the small H? contribution and the improved converging requirement may play a vital role in predicting the high-lying rovibrational energies and the rotational lines. Comparisons between physical predictions and mathematical extrapolations on the rotational lines are also given.

  6. sup 35 Cl and sup 1 H NMR study of anion binding to reduced bovine copper-zinc superoxide dismutase

    SciTech Connect

    Mota de Freitas, D.; Ramasamy, R. ); Ming, Lijune; Valentine, J.S. )

    1990-09-05

    Binding of chloride to reduced bovine copper-zinc superoxide dismutase (Cu{sub 2}Zn{sub 2}SOD) and chemically modified derivatives was monitored by the line width at half-height of the Cl{sup {minus}} resonance as measured by {sup 35}Cl nuclear magnetic resonance (NMR) spectroscopy. Reduced arginine-modified and reduced lysine-modified Cu{sub 2}Zn{sub 2}SOD (at concentrations of 2.14 {times} 10{sup {minus}4} M) caused less broadening of the Cl{sup {minus}} resonance line width of 0.1 M NaCl solutions than did reduced native protein when measured under the same conditions; Cl{sup {minus}} broadening with all protein derivatives decreased drastically in the presence of 0.05 M phosphate. The C-H and N-H proton resonances of histidyl imidazoles of reduced native and reduced lysine-modified Cu{sub 2}Zn{sub 2}SOD were shifted by addition of Cl{sup {minus}} (with apparent affinity constants of 12 and {approximately} 2 M{sup {minus}1}, respectively) whereas this anion had less effect in the {sup 1}H NMR spectrum of reduced arginine-modified Cu{sub 2}Zn{sub 2}SOD (affinity constant <2 M{sup {minus}1}) under the same conditions. phosphate caused relatively smaller changes on the {sup 1}H NMR resonances of all reduced protein derivatives. The competition measured by {sup 1}H NMR spectroscopy between chloride and phosphate for anion binding sites in the neighborhood of the Cu{sup 1} ion was much less than that for nonspecific Cl{sup {minus}} binding monitored by {sup 35}Cl NMR spectroscopy. It is concluded from these experiments that, in addition to the weak anion binding at or near the Cu{sup I} ion, Arg-141, Lys-120, and Lys-134 serve as major anion binding sites in the reduced native protein. 57 refs., 5 figs., 2 tabs.

  7. Prediction of P-branch emission spectral lines of NaF and (63)Cu(35)Cl molecules.

    PubMed

    Jiang, Yonghong; Sun, Weiguo; Zhang, Yi; Fu, Jia; Fan, Qunchao; Li, Huidong; Feng, Hao

    2016-01-15

    The analytical formula derived by Sun et al. in 2011 and used to predict the rotational lines for rovibrational diatomic systems is improved in this study. The new formula is obtained by adding a higher order spectral term H? that is neglected in our previous expression. A physical requirement is also added to the converging process to minimize the possible error of the predicted rotational line. All these are applied to study some rovibrational transition systems of (63)Cu(35)Cl and NaF molecules. The results indicate that the accuracy of the P-branch rotational lines predicted by this new formula is about one order of magnitude better than the results obtained using the previous formula, and that both the small H? contribution and the improved converging requirement may play a vital role in predicting the high-lying rovibrational energies and the rotational lines. Comparisons between physical predictions and mathematical extrapolations on the rotational lines are also given. PMID:26296252

  8. Direct studies of low-energy resonances in 31P(p, ) 28Si and 35Cl(p, )32S

    SciTech Connect

    Moazen, Brian; Matei, Catalin; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Hatarik, Robert; Jones, K. L.; Kozub, R. L.; Matos, M.; Nesaraja, Caroline D; O'Malley, Patrick; Pain, S. D.; Pelham, T.; Pittman, S. T.; Smith, Michael Scott

    2011-01-01

    Low-energy resonances in 31P(p,a)28Si and 35Cl(p,a)32S were studied directly in order to gain a better understanding of reaction cycling in the Si-Ar region in novae, supernovae, and X-ray bursts. Resonance strengths at Ec:m = 600 and 622 keV in 31P(p,a)28Si were measured as well as the Ec:m: = 611 keV resonance in 35Cl(p,a)32S, the lowest energy that any resonance in this reaction has been observed. The strengths of these resonances were found to be lower than previously determined through indirect methods, resulting in weak cycling in the Si-Ar region.

  9. The single NqrB and NqrC subunits in the Na(+)-translocating NADH: quinone oxidoreductase (Na(+)-NQR) from Vibrio cholerae each carry one covalently attached FMN.

    PubMed

    Casutt, Marco S; Schlosser, Andreas; Buckel, Wolfgang; Steuber, Julia

    2012-10-01

    The Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) is the prototype of a novel class of flavoproteins carrying a riboflavin phosphate bound to serine or threonine by a phosphodiester bond to the ribityl side chain. This membrane-bound, respiratory complex also contains one non-covalently bound FAD, one non-covalently bound riboflavin, ubiquinone-8 and a [2Fe-2S] cluster. Here, we report the quantitative analysis of the full set of flavin cofactors in the Na(+)-NQR and characterize the mode of linkage of the riboflavin phosphate to the membrane-bound NqrB and NqrC subunits. Release of the flavin by ?-elimination and analysis of the cofactor demonstrates that the phosphate group is attached at the 5'-position of the ribityl as in authentic FMN and that the Na(+)-NQR contains approximately 1.7mol covalently bound FMN per mol non-covalently bound FAD. Therefore, each of the single NqrB and NqrC subunits in the Na(+)-NQR carries a single FMN. Elimination of the phosphodiester bond yields a dehydro-2-aminobutyrate residue, which is modified with ?-mercaptoethanol by Michael addition. Proteolytic digestion followed by mass determination of peptide fragments reveals exclusive modification of threonine residues, which carry FMN in the native enzyme. The described reactions allow quantification and localization of the covalently attached FMNs in the Na(+)-NQR and in related proteins belonging to the Rhodobacter nitrogen fixation (RNF) family of enzymes. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). PMID:22366169

  10. Part I. Analyzing the distribution of gas law questions in chemistry textbooks. Part II. Chlorine-35 NQR spectra of group 1 and silver dichloromethanesulfonates

    NASA Astrophysics Data System (ADS)

    Gillette, Gabriel

    Part I. Two studies involving the gas law questions in eight high school and Advanced Placement/college chemistry textbooks were performed using loglinear analysis to look for associations among six variables. These variables included Bloom's Taxonomy (higher-order, lower-order), Book Type (high school, college), Question Format (multiple-choice, problem, short answer), Question Placement (in-chapter, end-of-chapter, test bank), Representation (macroscopic, microscopic, symbolic), and Arkansas Science Standard (conceptual, mathematical; gas laws, pressure conversion, stoichiometry). The first study, involving the conceptual gas law questions, found the Book Type and Question Placement variables had the biggest impact, each appearing in 5 of the 11 significant associations. The second study, involving the mathematical gas law questions, found the Question Placement had the biggest impact, appearing in 7 of the 11 significant associations, followed by Book Type and the Arkansas Science Standard variables, which appeared in 5 of the 11 significant associations. These studies showed that compared to the high school books, college books have fewer multiple-choice questions (compared to short-answer and problem questions), fewer in-chapter questions (compared to end-of-chapter and test bank questions), fewer questions in the chapters and more questions at the end of the chapters and fewer multiple-choice questions in and at the end of the books and more multiple-choice questions in the test banks. Part II. The dichloromethanesulfonate salts of several +1 charged cations, M+Cl2CHSO3 - (M = Li, Na, K, Rb Ag, Cs Tl) were synthesized and studied by 35Cl nuclear quadrupole resonance (NQR). Dichloromethanesulfonic acid was prepared by the methanolysis of dichloromethanesulfonyl chloride, which was neutralized with the metal carbonates to produce the corresponding metal dichloromethanesulfonate salts. This study completed the NQR investigation of the family of chloroacetates and chloromethanesulfonates of silver. The study suggests that the ability of organochlorine atoms to coordinate to silver ions decreases as the number of electron-withdrawing groups attached to carbon atom bound to the coordinating chlorine atom increases. The unusually large NQR spectral width found among M+Cl2CHCO2 - salts are not present among M+Cl2CHSO 3- salts and does not appear to be generally characteristic of the dichloromethyl family of salts.

  11. 14N NQR and relaxation in ammonium nitrate

    NASA Astrophysics Data System (ADS)

    Stephenson, David

    2015-04-01

    The complete 14N nuclear quadrupole resonance (NQR) spectrum of ammonium nitrate is presented recorded using two double resonance techniques - double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter ( ?) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T 1) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.

  12. NMR and NQR study of the thermodynamically stable quasicrystals

    SciTech Connect

    Shastri, A.

    1995-02-10

    {sup 27}Al and {sup 61,65}Cu NMR measurements are reported for powder samples of stable AlCuFe and AlCuRu icosahedral quasicrystals and their crystalline approximants, and for a AlPdMn single grain quasicrystal. Furthermore, {sup 27}Al NQR spectra at 4.2 K have been observed in the AlCuFe and AlCuRu samples. From the quadrupole perturbed NMR spectra at different magnetic fields, and from the zero field NQR spectra, a wide distribution of local electric field gradient (EFG) tensor components and principal axis system orientations was found at the Al site. A model EFG calculation based on a 1/1 AlCuFe approximant was successful in explaining the observed NQR spectra. It is concluded that the average local gradient is largely determined by the p-electron wave function at the Al site, while the width of the distribution is due to the lattice contribution to the EFG. Comparison of {sup 63}Cu NMR with {sup 27}Al NMR shows that the EFG distribution at the two sites is similar, but that the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more s-type wave function of the conduction electrons.

  13. Absence of Magnetic Dipolar Phase Transition and Evolution of Low-Energy Excitations in PrNb2Al20 with Crystal Electric Field ?3 Ground State: Evidence from 93Nb-NQR Studies

    NASA Astrophysics Data System (ADS)

    Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

    2015-07-01

    We report measurements of bulk magnetic susceptibility and 93Nb nuclear quadrupole resonance (NQR) in the Pr-based caged compound PrNb2Al20. By analyzing the magnetic susceptibility and magnetization, the crystal electric field (CEF) level scheme of PrNb2Al20 is determined to be ?3(0 K)-?4(21.32 K)-?5(43.98 K)-?1(51.16 K) within the framework of the localized 4f electron picture. The 93Nb-NQR spectra exhibit neither spectral broadening nor spectral shift upon cooling down to 75 mK. The 93Nb-NQR spin-lattice relaxation rate 1/T1 at 5 K depends on the frequency and remains almost constant below 5 K. The frequency dependence of 1/T1 is attributed to the magnetic fluctuation due to the hyperfine-enhanced 141Pr nuclear moment inherent in the nonmagnetic ?3 CEF ground state. The present NQR results provide evidence that no symmetry-breaking magnetic dipole order occurs down to 75 mK. Also, considering an invariant form of the quadrupole and octupole couplings between a 93Nb nucleus and Pr 4f electrons, Pr 4f quadrupoles and an octupole can couple with a 93Nb nuclear quadrupole moment and nuclear spin, respectively. Together with the results of bulk measurements, the present NQR results suggest that the possibility of a static quadrupole or octupole ordering can be excluded down to 100 mK. At low temperatures below 500 mK, however, the nuclear spin-echo decay rate gradually increases and the decay curve changes from Gaussian decay to Lorentzian decay, suggesting the evolution of a low-energy excitation.

  14. Determination of molecular stopping cross section of 12C, 16O, 28Si, 35Cl, 58Ni, 79Br, and 127I in silicon nitride

    NASA Astrophysics Data System (ADS)

    Barradas, N. P.; Bergmaier, A.; Mizohata, K.; Msimanga, M.; Räisänen, J.; Sajavaara, T.; Simon, A.

    2015-10-01

    Silicon nitride is a technologically important material in a range of applications due to a combination of important properties. Ion beam analysis techniques, and in particular, heavy ion elastic recoil detection analysis can be used to determine the stoichiometry of silicon nitride films, which often deviates from the ideal Si3N4, as well as the content of impurities such as hydrogen, even in the presence of other materials or in a matrix containing heavier elements. Accurate quantification of IBA results depends on the basic data used in the data analysis. Quantitative depth profiling relies on the knowledge of the stopping power cross sections of the materials studied for the ions involved, which in the case of HI-ERDA is both the primary beam, and the recoiled species. We measured the stopping cross section of 12C, 16O, 28Si, 35Cl, 58Ni, 79Br, and 127I in a well-characterised silicon nitride membrane. The measurements were made by independent groups utilising different experimental setups and methods. In some cases there is extensive overlap of the energy range in different experiments, allowing a comparison of the different results. The four independent data sets reported in this work are in excellent agreement with each other, in the cases where similar energy ranges were measured. On the other hand, the data are in most cases higher than calculations made with the interpolative schemes SRIM and MSTAR together with the Bragg rule. Better agreement is found with MSTAR in some of the cases studied. This work is a significant extension of the heavy ion stopping power data base for silicon nitride.

  15. Phase Transition and Orientational Disorder of the Cation in [(PyO)(H/D)][AuCl4] (PyO = C5H5NO) Crystal

    NASA Astrophysics Data System (ADS)

    Asaji, T.; Akiyama, E.; Tajima, F.; Eda, K.; Hashimoto, M.; Furukawa, Y.

    2004-12-01

    An orientational disorder of the cation in [(PyO)D][AuCl4] crystal was investigated by the 35Cl NQR and 1H NMR measurements. A structural phase transition was found at ca. 70 K from the temperature dependence of the NQR frequencies both in [(PyO)D][AuCl4] and [(PyO)H][AuCl4]. Temperature dependence of the spin-lattice relaxation time T 1 of the NQR of [AuCl4]- could be interpreted by an electric field gradient modulation due to the motion of the cation. Characteristics of T 1 of 35Cl NQR as well as that of 1H NMR suggest a dynamic orientational disorder of the cation.

  16. Herschel observations of interstellar chloronium. II - Detections toward G29.96-0.02, W49N, W51, and W3(OH), and determinations of the ortho-to-para and $^{35}$Cl/$^{37}$Cl isotopic ratios

    E-print Network

    Neufeld, David A; Gerin, Maryvonne; Goicoechea, Javier R; Goldsmith, Paul F; Gry, Cecile; Gupta, Harshal; Herbst, Eric; Indriolo, Nick; Lis, Dariusz; Menten, Karl M; Monje, Raquel; Mookerjea, Bhaswati; Persson, Carina; Sonnentrucker, Paule; Wolfire, Mark G

    2015-01-01

    We report additional detections of the chloronium molecular ion, H$_2$Cl$^+$, toward four bright submillimeter continuum sources: G29.96, W49N, W51, and W3(OH). With the use of the HIFI instrument on the Herschel Space Observatory, we observed the $2_{12}-1_{01}$ transition of ortho-H$_2^{35}$Cl$^+$ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the $N({\\rm H_2Cl^+})/N({\\rm H})$ ratio lie in the range $(0.9 - 4.8) \\times 10^{-9}$. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the $2_{12}-1_{01}$ transition of ortho-H$_2^{37}$Cl$^+$ at 780.053 GHz and the $1_{11}-0_{00}$ transition of para-H$_2^{35}$Cl$^+$ at 485.418 GHz. These observations imply $\\rm H_2^{35}Cl^+/H_2^{37}Cl^+$ column density ratios that are consisten...

  17. Z .Solid State Nuclear Magnetic Resonance 11 1998 139156 SQUID detected NMR and NQR

    E-print Network

    Augustine, Mathew P.

    Z .Solid State Nuclear Magnetic Resonance 11 1998 139­156 SQUID detected NMR and NQR Matthew P dc Superconducting QUantum Interference Device SQUID is a sensitive detector of magnetic flux to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned

  18. Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance

    E-print Network

    Romalis, Mike

    Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance S 20 November 2006 A radio-frequency tunable atomic magnetometer is developed for detection of nuclearHz 14 N NQR frequency of ammonium nitrate. A potential application of the magnetometer is detection

  19. The Conformational Changes Induced by Ubiquinone Binding in the Na+-pumping NADH:Ubiquinone Oxidoreductase (Na+-NQR) Are Kinetically Controlled by Conserved Glycines 140 and 141 of the NqrB Subunit*

    PubMed Central

    Strickland, Madeleine; Juárez, Oscar; Neehaul, Yashvin; Cook, Darcie A.; Barquera, Blanca; Hellwig, Petra

    2014-01-01

    Na+-pumping NADH:ubiquinone oxidoreductase (Na+-NQR) is responsible for maintaining a sodium gradient across the inner bacterial membrane. This respiratory enzyme, which couples sodium pumping to the electron transfer between NADH and ubiquinone, is not present in eukaryotes and as such could be a target for antibiotics. In this paper it is shown that the site of ubiquinone reduction is conformationally coupled to the NqrB subunit, which also hosts the final cofactor in the electron transport chain, riboflavin. Previous work showed that mutations in conserved NqrB glycine residues 140 and 141 affect ubiquinone reduction and the proper functioning of the sodium pump. Surprisingly, these mutants did not affect the dissociation constant of ubiquinone or its analog HQNO (2-n-heptyl-4-hydroxyquinoline N-oxide) from Na+-NQR, which indicates that these residues do not participate directly in the ubiquinone binding site but probably control its accessibility. Indeed, redox-induced difference spectroscopy showed that these mutations prevented the conformational change involved in ubiquinone binding but did not modify the signals corresponding to bound ubiquinone. Moreover, data are presented that demonstrate the NqrA subunit is able to bind ubiquinone but with a low non-catalytically relevant affinity. It is also suggested that Na+-NQR contains a single catalytic ubiquinone binding site and a second site that can bind ubiquinone but is not active. PMID:25006248

  20. Low-frequency nuclear quadrupole resonance with a dc SQUID

    SciTech Connect

    Chang, J.W.

    1991-07-01

    Conventional pure nuclear quadrupole resonance (NQR) is a technique well suited for the study of very large quadrupolar interactions. Numerous nuclear magnetic resonance (NMR) techniques have been developed for the study of smaller quadrupolar interactions. However, there are many nuclei which have quadrupolar interactions of intermediate strength. Quadrupolar interactions in this region have traditionally been difficult or unfeasible to detect. This work describes the development and application of a SQUID NQR technique which is capable of measuring intermediate strength quadrupolar interactions, in the range of a few hundred kilohertz to several megahertz. In this technique, a dc SQUID (Superconducting QUantum Interference Device) is used to monitor the longitudinal sample magnetization, as opposed to the transverse magnetization, as a rf field is swept in frequency. This allows the detection of low-frequency nuclear quadrupole resonances over a very wide frequency range with high sensitivity. The theory of this NQR technique is discussed and a description of the dc SQUID system is given. In the following chapters, the spectrometer is discussed along with its application to the study of samples containing half-odd-integer spin quadrupolar nuclei, in particular boron-11 and aluminum-27. The feasibility of applying this NQR technique in the study of samples containing integer spin nuclei is discussed in the last chapter. 140 refs., 46 figs., 6 tabs.

  1. NQR Line Broadening Due to Crystal Lattice Imperfections and Its Relationship to Shock Sensitivity

    NASA Astrophysics Data System (ADS)

    Caulder, S. M.; Buess, M. L.; Garroway, A. N.; Miller, P. J.

    2004-07-01

    The hydrodynamic hot spot model is used to explain the difference between shock sensitive and shock insensitive explosives. Among the major factors that influence the shock sensitivity of energetic compounds are the quality and particle size of the energetic crystals used to formulate the cast plastic bonded explosive. As do all energetic compounds, RDX and HMX exhibit internal crystal defects the magnitude and type of which depend on the manufacturing process used to synthesize and re-crystallize the energetic compound. Nuclear Quadrupole Resonance (NQR) spectroscopy was used to determine the crystal quality of RDX, HMX and CL-20 obtained from various manufacturers. The NQR experimental results are discussed. Cast plastic bonded explosives were made using the RDX and HMX obtained from the various manufacturers and subsequently subjected to the NOL large-scale gap test (LSGT). The results of the LSGT are discussed and correlated with the NQR results. A relationship between the crystal defect density and shock initiation pressure of the plastic bonded explosive is developed and discussed.

  2. Roles of the sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) on vibrio cholerae metabolism, motility and osmotic stress resistance.

    PubMed

    Minato, Yusuke; Fassio, Sara R; Kirkwood, Jay S; Halang, Petra; Quinn, Matthew J; Faulkner, Wyatt J; Aagesen, Alisha M; Steuber, Julia; Stevens, Jan F; Häse, Claudia C

    2014-01-01

    The Na+ translocating NADH:quinone oxidoreductase (Na+-NQR) is a unique respiratory enzyme catalyzing the electron transfer from NADH to quinone coupled with the translocation of sodium ions across the membrane. Typically, Vibrio spp., including Vibrio cholerae, have this enzyme but lack the proton-pumping NADH:ubiquinone oxidoreductase (Complex I). Thus, Na+-NQR should significantly contribute to multiple aspects of V. cholerae physiology; however, no detailed characterization of this aspect has been reported so far. In this study, we broadly investigated the effects of loss of Na+-NQR on V. cholerae physiology by using Phenotype Microarray (Biolog), transcriptome and metabolomics analyses. We found that the V. cholerae ?nqrA-F mutant showed multiple defects in metabolism detected by Phenotype Microarray. Transcriptome analysis revealed that the V. cholerae ?nqrA-F mutant up-regulates 31 genes and down-regulates 55 genes in both early and mid-growth phases. The most up-regulated genes included the cadA and cadB genes, encoding a lysine decarboxylase and a lysine/cadaverine antiporter, respectively. Increased CadAB activity was further suggested by the metabolomics analysis. The down-regulated genes include sialic acid catabolism genes. Metabolomic analysis also suggested increased reductive pathway of TCA cycle and decreased purine metabolism in the V. cholerae ?nqrA-F mutant. Lack of Na+-NQR did not affect any of the Na+ pumping-related phenotypes of V. cholerae suggesting that other secondary Na+ pump(s) can compensate for Na+ pumping activity of Na+-NQR. Overall, our study provides important insights into the contribution of Na+-NQR to V. cholerae physiology. PMID:24811312

  3. Ga NMR/NQR study of the kagom compound Nd This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Paris-Sud 11, Université de

    29 Si NMR and 69,71 Ga NMR/NQR study of the kagomé compound Nd 3 Ga 5 SiO 14 This article has been Contact us My IOPscience #12;29 Si NMR and 69,71 Ga NMR/NQR study of the kagom´e compound Nd3Ga5SiO14.zorko@ijs.si Abstract. We report a comprehensive 29 Si NMR and 69,71 Ga NMR/NQR study of the large- spin magnetically

  4. Measurement of in-situ stress in salt and rock using NQR techniques

    SciTech Connect

    Schempp, E.; Hirschfeld, T.; Klainer, S.

    1980-12-01

    A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising system involves pulsed nuclear double resonance detection; and alterative is to observe the quadrupolar splitting of the NMR signal. Choices to be made in the measurement and mapping techniques are discussed. The well-known perturbation of the homogenous stress field in the neighborhood of a borehole is shown to be advantageous from the point of view of obtaining directional information on the stress. Construction and operation of a borehole stress sensor are considered. The NQR technique seems feasible for measuring the magnitude and direction of underground stress with a resolution of about 25 psi, or 2.5% at 1000 psi. Downhole instrumentation suitable for in-situ determinations of stress appears within the state of the art. Additional tasks required on the project are identified.

  5. Herschel* Observations of Interstellar Chloronium. II. Detections toward G29.96-0.02, W49N, W51, and W3(OH), and Determinations of the Ortho-to-Para and 35Cl/37Cl Isotopic Ratios

    NASA Astrophysics Data System (ADS)

    Neufeld, David A.; Black, John H.; Gerin, Maryvonne; Goicoechea, Javier R.; Goldsmith, Paul F.; Gry, Cecile; Gupta, Harshal; Herbst, Eric; Indriolo, Nick; Lis, Dariusz; Menten, Karl M.; Monje, Raquel; Mookerjea, Bhaswati; Persson, Carina; Schilke, Peter; Sonnentrucker, Paule; Wolfire, Mark G.

    2015-07-01

    We report additional detections of the chloronium molecular ion, H2Cl+, toward four bright submillimeter continuum sources: G29.96-0.02, W49N, W51, and W3(OH). With the use of the HIFI instrument on board the Herschel Space Observatory, we observed the {2}12-{1}01 transition of ortho-H{}235Cl+ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the N({{{H}}}2{{Cl}}+)/N({{H}}) ratio lie in the range (0.9-4.8) × {10}-9. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the {2}12-{1}01 transition of ortho-H{}237Cl+ at 780.053 GHz and the {1}11-{0}00 transition of para-H{}235Cl+ at 485.418 GHz. These observations imply {{{H}}}235Cl+/H{}237Cl+ column density ratios that are consistent with the solar system 35Cl/37Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  6. Absolute NMR shielding scales and nuclear spin-rotation constants in 175LuX and 197AuX (X = 19F, 35Cl, 79Br and 127I)

    NASA Astrophysics Data System (ADS)

    Demissie, Taye B.; Jaszu?ski, Micha?; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-01

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in 175LuX and 197AuX (X = 19F, 35Cl, 79Br, 127I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  7. The high-resolution infrared spectrum of nitryl chloride: Rotational analysis of the [sup 35]ClNO[sub 2] [nu][sub 4] band around 6 [mu]m

    SciTech Connect

    Orphal, J.; Morillon-Chapey, M.; Guelachvili, G. . Lab. de Physique Moleculaire et Applications Univ. Paris 6 et 11, Orsay )

    1994-06-01

    Nitryl chloride (ClNO[sub 2]) is involved in heterogeneous stratospheric chemistry by the reaction of HCl with N[sub 2]O[sub 5] on polar stratospheric cloud particles. The present work reports the first high-resolution infrared absorption spectra of nitryl chloride. The authors have recorded two infrared absorption spectra of ClNO[sub 2] at room temperature between 450 and 2,450 cm[sup [minus]1] with a stepping-mode Fourier transform spectrometer at 0.0028 cm[sup [minus]1] nonapodized resolution. The spectrum shows rich, well-resolved rotational structure in the [nu][sub 6] (652 cm[sup [minus]1]), [nu][sub 2] (792 cm[sup [minus]1]), [nu][sub 1] (1,268 cm[sup [minus]1]), 2[nu][sub 6] (1,318 cm[sup [minus]1]), and [nu][sub 4] (1,684 cm[sup [minus]1]) bands. They have carried out a rotational analysis of the [nu][sub 4] band of [sup 35]ClNO[sub 2] around 1,684 cm[sup [minus]1], leading to the assignment of 1,691 b-type transitions. The authors have determined new rotational constants for the ground state, and the rotational constants for the [nu][sub 4] = 1 vibrational state.

  8. Absolute NMR shielding scales and nuclear spin-rotation constants in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br and (127)I).

    PubMed

    Demissie, Taye B; Jaszu?ski, Micha?; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-28

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides. PMID:26520517

  9. Mass and charge distributions in chlorine-induced nuclear reactions. [[sup 35]Cl at E/A = 15 MeV, [sup 37]Cl at E/A = 7. 3 MeV

    SciTech Connect

    Marchetti, A.A.

    1991-01-01

    Projectile-like fragments were detected and characterized in terms of A, Z, and energy for the reactions [sup 37]Cl on [sup 40]Ca and [sup 209]Bi at E/A = 7.3 MeV, and [sup 35]Cl, on [sup 209]Bi at E/A = 15 MeV, at angles close to the grazing angle. Mass and charge distributions were generated in the N-Z plane as a function of energy loss, and have been parameterized in terms of their centroids, variances, and coefficients of correlation. Due to experimental problems, the mass resolution corresponding to the [sup 31]Cl on [sup 209]Bi reaction was very poor. This prompted the study and application of a deconvolution technique for peak enhancement. The drifts of the charge and mass centroids for the system [sup 37]Cl on [sup 40]Ca are consistent with a process of mass and charge equilibration mediated by nucleon exchange between the two partners, followed by evaporation. The asymmetric systems show a strong drift towards larger asymmetry, with the production of neutron-rich nuclei. It was concluded that this is indicative of a net transfer of protons from the light to the heavy partner, and a net flow of neutrons in the opposite direction. The variances for all systems increase with energy loss, as it would be expected from a nucleon exchange mechanism; however, the variances for the reaction [sup 37]Cl on [sup 40]Ca are higher than those expected from that mechanism. The coefficients of correlation indicate that the transfer of nucleons between projectile and target is correlated. The results were compared to the predictions of two current models based on a stochastic nucleon exchange mechanism. In general, the comparisons between experimental and predicted variances support this mechanism; however, the need for more realistic driving forces in the model calculations is indicated by the disagreement between predicted and experimental centroids.

  10. Structural and Functional Investigation of Flavin Binding Center of the NqrC Subunit of Sodium-Translocating NADH:Quinone Oxidoreductase from Vibrio harveyi

    PubMed Central

    Bertsova, Yulia; Polovinkin, Vitaly; Gushchin, Ivan; Ishchenko, Andrii; Kovalev, Kirill; Mishin, Alexey; Kachalova, Galina; Popov, Alexander; Bogachev, Alexander; Gordeliy, Valentin

    2015-01-01

    Na+-translocating NADH:quinone oxidoreductase (NQR) is a redox-driven sodium pump operating in the respiratory chain of various bacteria, including pathogenic species. The enzyme has a unique set of redox active prosthetic groups, which includes two covalently bound flavin mononucleotide (FMN) residues attached to threonine residues in subunits NqrB and NqrC. The reason of FMN covalent bonding in the subunits has not been established yet. In the current work, binding of free FMN to the apo-form of NqrC from Vibrio harveyi was studied showing very low affinity of NqrC to FMN in the absence of its covalent bonding. To study structural aspects of flavin binding in NqrC, its holo-form was crystallized and its 3D structure was solved at 1.56 Å resolution. It was found that the isoalloxazine moiety of the FMN residue is buried in a hydrophobic cavity and that its pyrimidine ring is squeezed between hydrophobic amino acid residues while its benzene ring is extended from the protein surroundings. This structure of the flavin-binding pocket appears to provide flexibility of the benzene ring, which can help the FMN residue to take the bended conformation and thus to stabilize the one-electron reduced form of the prosthetic group. These properties may also lead to relatively weak noncovalent binding of the flavin. This fact along with periplasmic location of the FMN-binding domains in the vast majority of NqrC-like proteins may explain the necessity of the covalent bonding of this prosthetic group to prevent its loss to the external medium. PMID:25734798

  11. Intersegment hydrogen bonds as possible structural determinants of the N/Q/R site in glutamate receptors.

    PubMed Central

    Tikhonov, D B; Zhorov, B S; Magazanik, L G

    1999-01-01

    Specific electrophysiological and pharmacological properties of ionic channels in NMDA, AMPA, and kainate subtypes of ionotropic glutamate receptors (GluRs) are determined by the Asn (N), Gln (Q), and Arg (R) residues located at homologous positions of the pore-lining M2 segments (the N/Q/R site). Presumably, the N/Q/R site is located at the apex of the reentrant membrane loop and forms the narrowest constriction of the pore. Although the shorter Asn residues are expected to protrude in the pore to a lesser extent than the longer Gln residues, the effective dimension of the NMDA channel (corresponding to the size of the largest permeant organic cation) is, surprisingly, smaller than that of the AMPA channel. To explain this paradox, we propose that the N/Q/R residues form macrocyclic structures (rings) stabilized by H-bonds between a NH(2) group in the side chain of a given M2 segment and a C==O group of the main chain in the adjacent M2 segment. Using Monte Carlo minimization, we have explored conformational properties of the rings. In the Asn, but not in the Gln ring, the side-chain oxygens protruding into the pore may facilitate ion permeation and accept H-bonds from the blocking drugs. In this way, the model explains different electrophysiological and pharmacological properties of NMDA and non-NMDA GluR channels. The ring of H-bonded polar residues at the pore narrowing resembles the ring of four Thr(75) residues observed in the crystallographic structure of the KcsA K(+) channel. PMID:10512812

  12. (121,123)Sb and (75)As NMR and NQR investigation of the tetrahedrite (Cu12Sb4S13) - Tennantite (Cu12As4S13) system and other metal arsenides.

    PubMed

    Bastow, T J; Lehmann-Horn, J A; Miljak, D G

    2015-10-01

    This work is motivated by the recent developments in online minerals analysis in the mining and minerals processing industry via nuclear quadrupole resonance (NQR). Here we describe a nuclear magnetic resonance (NMR) and NQR study of the minerals tennantite (Cu12As4S13) and tetrahedrite (Cu12 Sb4S13). In the first part NQR lines associated with (75)As in tennantite and (121,123)Sb isotopes in tetrahedrite are reported. The spectroscopy has been restricted to an ambient temperature studies in accord with typical industrial conditions. The second part of this contribution reports nuclear quadrupole-perturbed NMR findings on further, only partially characterised, metal arsenides. The findings enhance the detection capabilities of NQR based analysers for online measurement applications and may aid to control arsenic and antimony concentrations in metal processing stages. PMID:26453410

  13. Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat

    NASA Technical Reports Server (NTRS)

    Borsa, F.; Rigamonti, A.

    1991-01-01

    La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for x ranging from 0 up to 0.3, with particular emphasis on the effect of doping on the Cu(2+) magnetic correlations and dynamics, are reviewed. In the low doping limit, x less than or equal to 0.05, the results can be interpreted consistently in terms of a simple phenomenological 'two-fluids' model whereby the effect of thermally-activated mobile O(2p) holes is the one of disrupting locally the Cu(2+) spin correlations. For x greater than or equal to 0.1, the results indicate the onset, as T approaches T(sub c)(+), of a strong coupling between Cu(2+) spins and the Fermi liquid of O(2p) holes leading to the apparent disappearance of localized Cu(2+) moment in connection with the opening of a superconducting gap.

  14. Ferromagnetic Spin Fluctuation and Unconventional Superconductivity in Rb_{2}Cr_{3}As_{3} Revealed by ^{75}As NMR and NQR.

    PubMed

    Yang, J; Tang, Z T; Cao, G H; Zheng, Guo-Qing

    2015-10-01

    We report ^{75}As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies on the superconductor Rb_{2}Cr_{3}As_{3} with a quasi-one-dimensional crystal structure. Below T?100??K, the spin-lattice relaxation rate (1/T_{1}) divided by temperature, 1/T_{1}T, increases upon cooling down to T_{c}=4.8??K, showing a Curie-Weiss-like temperature dependence. The Knight shift also increases with decreasing temperature. These results suggest ferromagnetic spin fluctuation. In the superconducting state, 1/T_{1} decreases rapidly below T_{c} without a Hebel-Slichter peak, and follows a T^{5} variation below T?3??K, which points to unconventional superconductivity with point nodes in the gap function. PMID:26551818

  15. Ferromagnetic Spin Fluctuation and Unconventional Superconductivity in Rb2Cr3As3 Revealed by 75As NMR and NQR

    NASA Astrophysics Data System (ADS)

    Yang, J.; Tang, Z. T.; Cao, G. H.; Zheng, Guo-qing

    2015-10-01

    We report 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies on the superconductor Rb2Cr3As3 with a quasi-one-dimensional crystal structure. Below T ˜100 K , the spin-lattice relaxation rate (1 /T1 ) divided by temperature, 1 /T1T , increases upon cooling down to Tc=4.8 K , showing a Curie-Weiss-like temperature dependence. The Knight shift also increases with decreasing temperature. These results suggest ferromagnetic spin fluctuation. In the superconducting state, 1 /T1 decreases rapidly below Tc without a Hebel-Slichter peak, and follows a T5 variation below T ˜3 K , which points to unconventional superconductivity with point nodes in the gap function.

  16. An ultra-broadband low-frequency magnetic resonance system

    NASA Astrophysics Data System (ADS)

    Mandal, S.; Utsuzawa, S.; Cory, D. G.; Hürlimann, M.; Poitzsch, M.; Song, Y.-Q.

    2014-05-01

    MR probes commonly employ resonant circuits for efficient RF transmission and low-noise reception. These circuits are narrow-band analog devices that are inflexible for broadband and multi-frequency operation at low Larmor frequencies. We have addressed this issue by developing an ultra-broadband MR probe that operates in the 0.1-3 MHz frequency range without using conventional resonant circuits for either transmission or reception. This “non-resonant” approach significantly simplifies the probe circuit and allows robust operation without probe tuning while retaining efficient power transmission and low-noise reception. We also demonstrate the utility of the technique through a variety of NMR and NQR experiments in this frequency range.

  17. Direct current superconducting quantum interference device spectrometer for pulsed nuclear magnetic resonance and nuclear quadrupole resonance at frequencies up to 5 MHz

    SciTech Connect

    TonThat, D.M.; Clarke, J.

    1996-08-01

    A spectrometer based on a dc superconducting quantum interference device (SQUID) has been developed for the direct detection of nuclear magnetic resonance (NMR) or nuclear quadrupole resonance (NQR) at frequencies up to 5 MHz. The sample is coupled to the input coil of the niobium-based SQUID via a nonresonant superconducting circuit. The flux locked loop involves the direct offset integration technique with additional positive feedback in which the output of the SQUID is coupled directly to a low-noise preamplifier. Precession of the nuclear quadrupole spins is induced by a magnetic field pulse with the feedback circuit disabled; subsequently, flux locked operation is restored and the SQUID amplifies the signal produced by the nuclear free induction signal. The spectrometer has been used to detect {sup 27}Al NQR signals in ruby (Al{sub 2}O{sub 3}[Cr{sup 3+}]) at 359 and 714 kHz. {copyright} {ital 1996 American Institute of Physics.}

  18. Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat

    NASA Technical Reports Server (NTRS)

    Borsa, F.; Rigamonti, A.

    1990-01-01

    La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for O = to or less than 0.3 and in the temperature range 1.6 + 450 K are analyzed in terms of Cu(++) magnetic correlations and dynamics. It is described how the magnetic correlations that would result from Cu-Cu exchange are reduced by mobile charge defects related to x-doping. A comprehensive picture is given which explains satisfactorily the x and T dependence of the correlation time, of the correlation length and of the Neel temperature T(sub n)(x) as well as being consistent with known electrical resistivity and magnetic susceptibility measurements. It is discussed how, in the superconducting samples, the mobile defects also cause the decrease, for T yields T(sub c)(+) of the hyperfine Cu electron-nucleus effective interaction, leading to the coexistence of quasi-localized, reduced magnetic moments from 3d Cu electrons and mobile oxygen p-hole carriers. The temperature dependence of the effective hyperfine field around the superconducting transition yields an activation energy which could be related to the pairing energy. New specific heat measurements are also presented and discussed in terms of the above picture.

  19. Electronic properties of Y-Ba-Cu-O superconductors as seen by Cu and O NMR/NQR

    NASA Technical Reports Server (NTRS)

    Brinkmann, D.

    1995-01-01

    Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) allow the investigation of electronic properties at the atomic level. We will report on such studies of typical members of the the Y-Ba-Cu-O family such as YBa2Cu30(6 + x) (1-2-3-(6 + x)), YBa2Cu4O8 (1-2-4) and Y2Ba4Cu7015 (2-4-7) with many examples of recent work performed in our laboratory. In particular, we will deal with Knight shift and relaxation studies of copper and oxygen. We will discuss important issues of current studies such as: (1) Existence of a common electronic spin-susceptibility in the planes (and perhaps in the chains) of 1-2-4; (2) Strong evidence for the existence of a pseudo spin-gap of the antiferromagnetic fluctuations in 1-2-4 and 2-4-7; (3) Evidence for d-wave pairing in 1-2-4; (4) Strong coupling of inequivalent Cu-O planes in 2-4-7 and possible origin for the high Tc value of this compound; and (5) The possibility to describe NMR data in the framework of a charge-excitation picture.

  20. Ferromagnetic Quantum Critical Fluctuations and Anomalous Coexistence of Ferromagnetism and Superconductivity in UCoGe Revealed by Co-NMR and NQR Studies

    NASA Astrophysics Data System (ADS)

    Ohta, Tetsuya; Nakai, Yusuke; Ihara, Yoshihiko; Ishida, Kenji; Deguchi, Kazuhiko; Sato, Noriaki K.; Satoh, Isamu

    2008-02-01

    Co nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) studies were carried out for the recently discovered UCoGe, in which the ferromagnetic and superconducting (SC) transitions are reported to occur at TCurie˜ 3 K and TS˜ 0.8 K [Huy et al.: Phys. Rev. Lett. 99 (2007) 067006], in order to investigate the coexistence of ferromagnetism and superconductivity as well as the normal-state and SC properties from a microscopic point of view. From the nuclear spin-lattice relaxation rate 1/T1 and Knight-shift measurements, we confirm that ferromagnetic fluctuations that possess a quantum critical character are present above TCurie and also the occurrence of a ferromagnetic transition at 2.5 K in our polycrystalline sample. The magnetic fluctuations in the normal state show that UCoGe is an itinerant ferromagnet similar to ZrZn2 and YCo2. The onset SC transition is identified at TS˜ 0.7 K, below which 1/T1 arising from 30% of the volume fraction starts to decrease due to the opening of the SC gap. This component of 1/T1, which follows a T3 dependence in the temperature range 0.3-0.1 K, coexists with the magnetic components of 1/T1 showing a \\sqrt{T} dependence below TS. From the NQR measurements in the SC state, we suggest that the self-induced vortex state is realized in UCoGe.

  1. Suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by As75 NMR/NQR measurements

    SciTech Connect

    Furukawa, Yuji; Roy, Beas; Ran, Sheng; Budko, Sergey L.; Canfield, Paul C.

    2014-03-20

    The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the high-temperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic (AFM) spin correlations are realized in the high-temperature tetragonal phase, no trace of the AFM spin correlations can be found in the nonsuperconducting, low-temperature, collapsed tetragonal (cT) phase. Given that there is no magnetic broadening in As75 NMR spectra, together with the T-independent behavior of magnetic susceptibility ? and the T dependence of 1/T1T?, we conclude that Fe spin correlations are completely quenched statically and dynamically in the nonsuperconducting cT phase in CaFe2As2.

  2. Secondary signals in two-frequency nuclear quadrupole resonance on (14)N nuclei with I=1.

    PubMed

    Mozzhukhin, G V; Rameev, B Z; Do?an, N; Akta?, B

    2008-07-01

    Our experimental and theoretical studies show that using two-frequency excitation of (14)N nuclei it is possible to observe secondary NQR signals at one of the three possible transitions due to irradiation of another adjacent transition. As a result of the pulse sequence applied to the adjacent transition the spin-echo signals on the detected transition are observed after essential time interval from the initial single pulse on this frequency. Experiments have been performed on the (14)N nuclei in the sodium nitrite (NaNO(2)) and the military explosive hexahydro-1,3,5-trinitro-s-triazine C(3)H(6)N(6)O(6) (RDX). PMID:18455453

  3. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

  4. Emission spectroscopy, harmonic vibrational frequencies, and improved ground state structures of jet-cooled monochloro- and monobromosilylene (HSiCl and HSiBr)

    NASA Astrophysics Data System (ADS)

    Hostutler, David A.; Ndiege, Nicholas; Clouthier, Dennis J.; Pauls, Steven W.

    2001-09-01

    The ground state harmonic frequencies of gas phase H/DSi35Cl and H/DSi79Br have been determined by exciting single vibronic bands of the à 1A?-X˜1A' electronic transition and recording the dispersed fluorescence. The jet-cooled radicals were produced in a pulsed discharge jet using H/DSiX3 (X=Cl or Br) precursors. The emission data were fitted to an anharmonic model and a normal coordinate analysis of the harmonic frequencies allowed the determination of five of the six force constants of each molecule. Using previously obtained v?=0 rotational constants and the improved force fields, average (rz) and estimated equilibrium (rez) structures were calculated for both monohalosilylenes. The validity of the force constants was evaluated by comparing calculated and observed zero-point inertial defects and by simulating the Franck-Condon profiles of the observed emission spectra in the harmonic approximation.

  5. Nuclear quadrupole resonance characterization of carbamazepine cocrystals.

    PubMed

    Seliger, Janez; Žagar, Veselko

    2012-01-01

    Nuclear quadrupole resonance (NQR) is used as a method for the characterization of cocrystals and crystal polymorphs. (14)N NQR spectra of several cocrystals of carbamazepine have been measured together with the (14)N NQR spectra of cocrystal formers. The results show that the (14)N NQR spectrum of a cocrystal and the (14)N NQR spectra of cocrystal formers differ well outside the experimental resolution. It is further described how the NQDR techniques, that have been used to measure the (14)N NQR frequencies, can be used to check the homogeneity of a polycrystalline sample and to monitor the stability of a metastable crystal polymorph. PMID:23021594

  6. 34 High Frequency Electronics High Frequency Design

    E-print Network

    Popovic, Zoya

    consists of a baseband or IF modulator, an up-converter, and a power- amplifier chain (Figure 20 Electronics Copyright © 2003 Summit Technical Media, LLC #12;36 High Frequency Electronics High Frequency

  7. Converting Frequency Responses to Daily Frequency

    Cancer.gov

    Frequency information on the DSQ in NHANES 2009-2010 was collected using a rate and time unit (e.g., 3 times per week). A different response format consisting of a set number of frequency categories is used in the self-administered paper questionnaire (link to questionnaire) ,. In both cases, the frequency responses are converted to a common unit of time, i.e. times per day.

  8. NMR and NQR parameters of ethanol crystal

    E-print Network

    Milinkovic, M

    2012-01-01

    Electric field gradients and chemical shielding tensors of the stable monoclinic crystal phase of ethanol are computed. The projector-augmented wave (PAW) and gauge-including projector-augmented wave (GIPAW) models in the periodic plane-wave density functional theory are used. The crystal data from X-ray measurements, as well as the structures where either all atomic, or only hydrogen atom positions are optimized in the density functional theory are analyzed. These structural models are also studied by including the semi-empirical Van der Waals correction to the density functional theory. Infrared spectra of these five crystal models are calculated.

  9. 46 High Frequency Electronics High Frequency Design

    E-print Network

    Popovic, Zoya

    46 High Frequency Electronics High Frequency Design RF POWER AMPLIFIERS RF and Microwave Power- increasing challenges in the design of power amplifiers and transmit- ters. A single W-CDMA signal in the near future. RF Pulse-Width Modulation Variation of the duty ratio (pulse width) of a class-D RF PA

  10. 38 High Frequency Electronics High Frequency Design

    E-print Network

    Popovic, Zoya

    38 High Frequency Electronics High Frequency Design RF POWER AMPLIFIERS RF and Microwave Power are incorpo- rated into power amplifiers and transmit- ters for the dual purposes of improving linearity, and predistortion. 8a. FEEDBACK Feedback linearization can be applied either directly around the RF amplifier (RF

  11. Frequency Response Tool

    Energy Science and Technology Software Center (ESTSC)

    2014-03-13

    According to the North American Electric Reliability Corporation (NERC) definition: ?Frequency response is a measure of an Interconnection?s ability to stabilize frequency immediately following the sudden loss of generation or load, and is a critical component of the reliable operation of the Bulk-Power System, particularly during disturbances and recoveries. Failure to maintain frequency can disrupt the operation of equipment and initiate disconnection of power plant equipment to prevent it from being damaged, which could leadmore »to wide-spread blackouts.? Frequency Response Tool automates the power system frequency response analysis process. The tool performs initial estimation of the system frequency parameters (initial frequency, minimum frequency, settling point). User can visually inspect and adjust these parameters. The tool also calculates the frequency response performance metrics of the system, archives the historic events and baselines the system performance. Frequency response performance characteristics of the system are calculated using phasor measurement unit (PMU) information. Methodology of the frequency response performance assessment implemented in the tool complies with the NERC Frequency response standard.« less

  12. Eastern Frequency Response Study

    SciTech Connect

    Miller, N.W.; Shao, M.; Pajic, S.; D'Aquila, R.

    2013-05-01

    This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

  13. INCREASING MILKING FREQUENCY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Milk Yield increases by a fixed amount due to increased milking frequency and not by some percentage of previous milk yields. Six times-a-day milking frequency from calving through six weeks post-partum results in not only increased production during the period of high frequency milking by also in ...

  14. Making Sense of Frequency.

    ERIC Educational Resources Information Center

    Larsen-Freeman, Diane

    2002-01-01

    Responds to Ellis (2002), which focuses on frequency in language processing, language use, and language acquisition. Contextualizes the frequency factor in terms of the evolution of second language acquisition (SLA) research. Suggests that although relevant and important, the frequency factor requires greater definition and qualification.…

  15. Frequency selective infrared sensors

    DOEpatents

    Davids, Paul; Peters, David W

    2013-05-28

    A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.

  16. Frequency selective infrared sensors

    DOEpatents

    Davids, Paul; Peters, David W

    2014-11-25

    A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.

  17. Radio frequency detection assembly and method for detecting radio frequencies

    SciTech Connect

    Cown, Steven H.; Derr, Kurt Warren

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  18. Optical frequency standards

    NASA Astrophysics Data System (ADS)

    Helmcke, Juergen; Riehle, Fritz; Morinaga, Atsuo; Ishikawa, Jun

    1989-04-01

    Frequency standards operating in the optical range promise very low frequency uncertainties due to the high spectral resolution and the small sensitivity to external fields. Basic ideas and concepts for the development of optical frequency standards are reviewed with emphasis to laser cooling and ion storing. Utilizing cooled absorbers, potential fractional frequency uncertainties below 10-15 are envisaged. Phase-coherent frequency measurements of laser radiation at lambda = 3.39 microns and a concept for an extension towards the visible range are discussed. A Ca optical frequency stabilized to the intercombination line (3P1 - 1S0, lambda roughly 657 nm) utilizing Ramsey excitation of a single recoil component is described. The present estimated fractional uncertainty to find the Ca line center is about 2.3 x 10 to the -12th. It can probably be improved significantly by reducing phase shifts of the Ramsey excitation and by atomic beam cooling.

  19. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Waarts, Robert G. (Inventor)

    2001-01-01

    A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  20. Radio Frequency Name ITU Band # Frequency Range Ultra-low frequency (ULF) 1 3 -30 Hz

    E-print Network

    Hz - 30 kHz Low frequency (LF) 5 30 kHz - 300 kHz Medium frequency (MF) 6 300 kHz - 3 MHz High frequencyRadio Frequency Name ITU Band # Frequency Range Ultra-low frequency (ULF) 1 3 - 30 Hz Super low frequency(SLF) 2 30Hz - 300Hz Extremely low frequency (ELF) 3 300 Hz - 3 kHz Very low frequency (VLF) 4 3 k

  1. Nonlinear Frequency Compression

    PubMed Central

    Scollie, Susan; Glista, Danielle; Seelisch, Andreas

    2013-01-01

    Frequency lowering technologies offer an alternative amplification solution for severe to profound high frequency hearing losses. While frequency lowering technologies may improve audibility of high frequency sounds, the very nature of this processing can affect the perceived sound quality. This article reports the results from two studies that investigated the impact of a nonlinear frequency compression (NFC) algorithm on perceived sound quality. In the first study, the cutoff frequency and compression ratio parameters of the NFC algorithm were varied, and their effect on the speech quality was measured subjectively with 12 normal hearing adults, 12 normal hearing children, 13 hearing impaired adults, and 9 hearing impaired children. In the second study, 12 normal hearing and 8 hearing impaired adult listeners rated the quality of speech in quiet, speech in noise, and music after processing with a different set of NFC parameters. Results showed that the cutoff frequency parameter had more impact on sound quality ratings than the compression ratio, and that the hearing impaired adults were more tolerant to increased frequency compression than normal hearing adults. No statistically significant differences were found in the sound quality ratings of speech-in-noise and music stimuli processed through various NFC settings by hearing impaired listeners. These findings suggest that there may be an acceptable range of NFC settings for hearing impaired individuals where sound quality is not adversely affected. These results may assist an Audiologist in clinical NFC hearing aid fittings for achieving a balance between high frequency audibility and sound quality. PMID:23539261

  2. Frequency selective terahertz retroreflectors

    NASA Astrophysics Data System (ADS)

    Williams, Richard James

    The use of novel optical structures operating at terahertz frequencies in industrial and military applications continues to grow. Some of these novel structures include gratings, frequency selective surfaces, metamaterials and metasurfaces, and retroreflectors. A retroreflector is a device that exhibits enhanced backscatter by concentrating the reflected wave in the direction of the source. Retroreflectors have applications in a variety of diverse fields such as aviation, radar systems, antenna technology, communications, navigation, passive identification, and metrology due to their large acceptance angles and frequency bandwidth. This thesis describes the design, fabrication, and characterization of a retroreflector designed for terahertz frequencies and the incorporation of a frequency selective surface in order to endow the retroreflector with narrow-band frequency performance. The radar cross section of several spherical lens reflectors operating at terahertz frequencies was investigated. Spherical lens reflectors with diameters ranging from 2 mm to 8 mm were fabricated from fused silica ball lenses and their radar cross section was measured at 100 GHz, 160 GHz, and 350 GHz. Crossed-dipole frequency selective surfaces exhibiting band-pass characteristics at 350 GHz fabricated from 12 um-thick Nickel screens were applied to the apertures of the spherical lens reflectors. The radar cross section of the frequency selective retroreflectors was measured at 160 GHz and 350 GHz to demonstrate proof-of-concept of narrow-band terahertz performance.

  3. Frequency Response Analysis Tool

    SciTech Connect

    Etingov, Pavel V.; Kosterev, Dmitry; Dai, T.

    2014-12-31

    Frequency response has received a lot of attention in recent years at the national level, which culminated in the development and approval of North American Electricity Reliability Corporation (NERC) BAL-003-1 Frequency Response and Frequency Bias Setting Reliability Standard. This report is prepared to describe the details of the work conducted by Pacific Northwest National Laboratory (PNNL) in collaboration with the Bonneville Power Administration and Western Electricity Coordinating Council (WECC) Joint Synchronized Information Subcommittee (JSIS) to develop a frequency response analysis tool (FRAT). The document provides the details on the methodology and main features of the FRAT. The tool manages the database of under-frequency events and calculates the frequency response baseline. Frequency response calculations are consistent with frequency response measure (FRM) in NERC BAL-003-1 for an interconnection and balancing authority. The FRAT can use both phasor measurement unit (PMU) data, where available, and supervisory control and data acquisition (SCADA) data. The tool is also capable of automatically generating NERC Frequency Response Survey (FRS) forms required by BAL-003-1 Standard.

  4. Frequency standards for communications

    NASA Astrophysics Data System (ADS)

    Stein, Samuel R.; Vig, John R.

    1991-10-01

    The fundamentals of quartz and atomic frequency standards are reviewed. The subjects discussed include: crystal resonators and oscillators, atomic oscillators, oscillator types, and the characteristic and limitations of temperature-compensated crystal oscillators (TCXO), oven-controlled crystal oscillators (OCXO), rubidium frequency standards, cesium beam frequency standards and hydrogen masers. The oscillator instabilities discussed include: aging, noise, frequency vs. temperature, warmup, acceleration effects, magnetic field effects, atmospheric pressure effects, radiation effects, and interactions among the various effects. Guidelines are provided for oscillator comparison and selection. Discussions of time transfer techniques and specifications are also included, as are references and suggestions for further reading.

  5. Frequency standards for communications

    NASA Astrophysics Data System (ADS)

    Stein, Samuel R.; Vig, John R.

    1991-01-01

    The fundamentals of quartz and atomic frequency standards are reviewed. The subjects discussed include: crystal resonators and oscillators, atomic oscillators, oscillator types, and the characteristics and limitations of temperature-compensated crystal oscillators (TCXO), oven-controlled crystals oscillators (OCXO), rubidium frequency standards, cesium beam frequency standards and hydrogen masers. The oscillator instabilities discussed include: aging, noise, frequency vs. temperature, warmup acceleration effects, magnetic field effects, atmospheric pressure effects, radiation effects, and interactions among the various effects. Guidelines are provided for oscillator comparison and selection. A discussion of time transfer techniques, and specifications are also included, as are references and suggestions for further reading.

  6. Probability and Relative Frequency

    NASA Astrophysics Data System (ADS)

    Drieschner, Michael

    2015-10-01

    The concept of probability seems to have been inexplicable since its invention in the seventeenth century. In its use in science, probability is closely related with relative frequency. So the task seems to be interpreting that relation. In this paper, we start with predicted relative frequency and show that its structure is the same as that of probability. I propose to call that the `prediction interpretation' of probability. The consequences of that definition are discussed. The "ladder"-structure of the probability calculus is analyzed. The expectation of the relative frequency is shown to be equal to the predicted relative frequency. Probability is shown to be the most general empirically testable prediction.

  7. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1984-12-25

    Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

  8. Frequency modulated oscillator

    NASA Technical Reports Server (NTRS)

    Honnell, M. A. (inventor)

    1977-01-01

    A frequency modulated push-pull oscillator in which the non-linear characteristic of varactors producing frequency modulation is compensated for by an opposite non-linear characteristic of a field effect transistor providing modulating bias to the varactors is described.

  9. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

    1984-01-01

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  10. Microfabricated ion frequency standard

    DOEpatents

    Schwindt, Peter (Albuquerque, NM); Biedermann, Grant (Albuquerque, NM); Blain, Matthew G. (Albuquerque, NM); Stick, Daniel L. (Albuquerque, NM); Serkland, Darwin K. (Albuquerque, NM); Olsson, III, Roy H. (Albuquerque, NM)

    2010-12-28

    A microfabricated ion frequency standard (i.e. an ion clock) is disclosed with a permanently-sealed vacuum package containing a source of ytterbium (Yb) ions and an octupole ion trap. The source of Yb ions is a micro-hotplate which generates Yb atoms which are then ionized by a ultraviolet light-emitting diode or a field-emission electron source. The octupole ion trap, which confines the Yb ions, is formed from suspended electrodes on a number of stacked-up substrates. A microwave source excites a ground-state transition frequency of the Yb ions, with a frequency-doubled vertical-external-cavity laser (VECSEL) then exciting the Yb ions up to an excited state to produce fluorescent light which is used to tune the microwave source to the ground-state transition frequency, with the microwave source providing a precise frequency output for the ion clock.

  11. High Frequency Ultrasonic Imaging

    PubMed Central

    Shung, K Kirk

    2010-01-01

    High frequency ultrasonic imaging is considered by many to be the next frontier in ultrasound. It has many clinical applications ranging from imaging the eye and skin to small animal imaging. Small animal imaging has recently generated intense interest for the purpose of evaluating the efficacy of drugs and gene therapy. Commercial high frequency scanners often termed “ultrasonic biomicroscope”, or UBM, all use mechanically scanned single element transducers at frequencies between 30 to 60 MHz with a frame rate of 30 frames/second or lower. To alleviate problems with UBMs which include mechanical motion and fixed focusing, high frequency linear arrays and imaging systems in the 20–50 MHz range have been developed. In this paper, current efforts in the development of high frequency ultrasonic imaging will be reviewed and potential biomedical applications discussed. PMID:20445825

  12. Frequency comb swept lasers

    PubMed Central

    Tsai, Tsung-Han; Zhou, Chao; Adler, Desmond C.; Fujimoto, James G.

    2010-01-01

    We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a ~?1.2dB sensitivity roll off over ~3mm range, compared to conventional swept source and FDML lasers which have ?10dB and ?5dB roll offs, respectively. Measurements at very long ranges are possible with minimal sensitivity loss, however reflections from outside the principal measurement range of 0–3mm appear aliased back into the principal range. In addition, the frequency comb output from the lasers are equally spaced in frequency (linear in k-space). The filtered laser output can be used to self-clock the OCT interference signal sampling, enabling direct fast Fourier transformation of the fringe signals, without the need for fringe recalibration procedures. The design and operation principles of FC swept lasers are discussed and designs for short cavity lasers for OCT and interferometric measurement applications are proposed. PMID:19997365

  13. Supernova frequency estimates

    SciTech Connect

    Tsvetkov, D.Y.

    1983-01-01

    Estimates of the frequency of type I and II supernovae occurring in galaxies of different types are derived from observational material acquired by the supernova patrol of the Shternberg Astronomical Institute.

  14. Graphene Frequency Multipliers

    E-print Network

    Wang, Han

    In this letter, the ambipolar transport properties of graphene flakes have been used to fabricate full-wave signal rectifiers and frequency-doubling devices. By correctly biasing an ambipolar graphene field-effect transistor ...

  15. On letter frequency effects.

    PubMed

    New, Boris; Grainger, Jonathan

    2011-10-01

    In four experiments we examined whether the frequency of occurrence of letters affects performance in the alphabetic decision task (speeded letter vs. pseudo-letter classification). Experiments 1A and 1B tested isolated letters and pseudo-letters presented at fixation, and Experiments 2A and 2B tested the same stimuli inserted at the 1st, 3rd, or 5th position in a string of Xs. Significant negative correlations between letter frequency and response times to letter targets were found in all experiments. The correlations were found to be stronger for token frequency counts compared with both type frequency and frequency rank, stronger for frequency counts based on a book corpus compared with film subtitles, and stronger for measures counting occurrences as the first letter of words compared with inner letters and final letters. Correlations for letters presented in strings of Xs were found to depend on letter case and position-in-string. The results are in favor of models of word recognition that implement case-specific and position-specific letter representations. PMID:21855049

  16. Fundamentals of Time and Frequency

    E-print Network

    17 Fundamentals of Time and Frequency 17.1 Introduction Coordinated Universal Time (UTC) 17.2 Time and Frequency Measurement Accuracy · Stability 17.3 Time and Frequency Standards Quartz Oscillators · Rubidium Oscillators · Cesium Oscillators 17.4 Time and Frequency Transfer Fundamentals of Time and Frequency Transfer

  17. Image restoration using fast Fourier and wavelet transforms

    NASA Astrophysics Data System (ADS)

    Harrod, William J.; Nagy, James G.; Plemmons, Robert J.

    1994-02-01

    Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a proof-of-concept NQR explosives detector which interrogates a volume of 300 liters (10 ft3). With minimal modification to the existing explosives detector, we can detect operationally relevant quantities of (free base) cocaine within the 300-liter inspection volume in 6 seconds. We are presently extending this approach to the detection of heroin base and also examining 14N and 35,37Cl pure NQR for detection of the hydrochloride forms of both materials. An adaptation of this NQR approach may be suitable for scanning personnel for externally carried contraband and explosives. We first outline the basics of the NQR approach, highlighting strengths and weaknesses, and then present representative results for RDX and cocaine detection. We also present a partial compendium of relevant NQR parameters measured for some materials of interest.

  18. Narcotics and explosives detection by 14N pure nuclear quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Garroway, Allen N.; Buess, Michael L.; Yesinowski, James P.; Miller, Joel B.

    1994-03-01

    Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a proof-of-concept NQR explosives detector which interrogates a volume of 300 liters (10 ft3). With minimal modification to the existing explosives detector, we can detect operationally relevant quantities of (free base) cocaine within the 300-liter inspection volume in 6 seconds. We are presently extending this approach to the detection of heroin base and also examining 14N and 35,37Cl pure NQR for detection of the hydrochloride forms of both materials. An adaptation of this NQR approach may be suitable for scanning personnel for externally carried contraband and explosives. We first outline the basics of the NQR approach, highlighting strengths and weaknesses, and then present representative results for RDX and cocaine detection. We also present a partial compendium of relevant NQR parameters measured for some materials of interest.

  19. Frequency Standards and Metrology

    NASA Astrophysics Data System (ADS)

    Maleki, Lute

    2009-04-01

    Preface / Lute Maleki -- Symposium history / Jacques Vanier -- Symposium photos -- pt. I. Fundamental physics. Variation of fundamental constants from the big bang to atomic clocks: theory and observations (Invited) / V. V. Flambaum and J. C. Berengut. Alpha-dot or not: comparison of two single atom optical clocks (Invited) / T. Rosenband ... [et al.]. Variation of the fine-structure constant and laser cooling of atomic dysprosium (Invited) / N. A. Leefer ... [et al.]. Measurement of short range forces using cold atoms (Invited) / F. Pereira Dos Santos ... [et al.]. Atom interferometry experiments in fundamental physics (Invited) / S. W. Chiow ... [et al.]. Space science applications of frequency standards and metrology (Invited) / M. Tinto -- pt. II. Frequency & metrology. Quantum metrology with lattice-confined ultracold Sr atoms (Invited) / A. D. Ludlow ... [et al.]. LNE-SYRTE clock ensemble: new [symbol]Rb hyperfine frequency measurement - spectroscopy of [symbol]Hg optical clock transition (Invited) / M. Petersen ... [et al.]. Precise measurements of S-wave scattering phase shifts with a juggling atomic clock (Invited) / S. Gensemer ... [et al.]. Absolute frequency measurement of the [symbol] clock transition (Invited) / M. Chwalla ... [et al.]. The semiclassical stochastic-field/atom interaction problem (Invited) / J. Camparo. Phase and frequency noise metrology (Invited) / E. Rubiola ... [et al.]. Optical spectroscopy of atomic hydrogen for an improved determination of the Rydberg constant / J. L. Flowers ... [et al.] -- pt. III. Clock applications in space. Recent progress on the ACES mission (Invited) / L. Cacciapuoti and C. Salomon. The SAGAS mission (Invited) / P. Wolf. Small mercury microwave ion clock for navigation and radioScience (Invited) / J. D. Prestage ... [et al.]. Astro-comb: revolutionizing precision spectroscopy in astrophysics (Invited) / C. E. Kramer ... [et al.]. High frequency very long baseline interferometry: frequency standards and imaging an event horizon (Invited) / S. Doeleman. Optically-pumped space cesium clock for Galileo: results of the breadboard / R. Ruffieux ... [et al.] -- pt. IV. Optical clocks I: lattice clocks. Optical lattice clock: seven years of progress and next steps (Invited) / H. Katori, M. Takamoto and T. Akatsuka. The Yb optical lattice clock (Invited) / N. D. Demke ... [et al.]. Optical Lattice clock with Sr atoms (Invited) / P. G. Westergaard ... [et al.]. Development of an optical clock based on neutral strontium atoms held in a lattice trap / E. A. Curtis ... [et al.]. Decoherence and losses by collisions in a [symbol]Sr lattice clock / J. S. R. Vellore Winfred ... [et al.]. Lattice Yb optical clock and cryogenic Cs fountain at INRIM / F. Levi ... [et al.] -- pt. V. Optical clocks II: ion clocks. [Symbol]Yb+ single-ion optical frequency standards (Invited) / Chr. Tamm ... [et al.]. An optical clock based on a single trapped [symbol]Sr+ ion (Invited) / H. S. Margolis ... [et al.]. A trapped [symbol]Yb+ ion optical frequency standard based on the [symbol] transition (Invited) / P. Gill ... [et al.]. Overview of highly accurate RF and optical frequency standards at the National Research Council of Canada (Invited) / A. A. Madej ... [et al.] -- pt. VI. Optical frequency combs. Extreme ultraviolet frequency combs for spectroscopy (Invited) / A. Ozawa ... [et al.]. Development of an optical clockwork for the single trapped strontium ion standard at 445 THz / J. E. Bernard ... [et al.]. A phase-coherent link between the visible and infrared spectral ranges using a combination of CW OPO and femtosecond laser frequency comb / E. V. Kovalchuk and A. Peters. Improvements to the robustness of a TI: sapphire-based femtosecond comb at NPL / V. Tsatourian ... [et al.] -- pt. VII. Atomic microwave standards. NIST FI and F2 (Invited) / T. P. Heavner ... [et al.]. Atomic fountains for the USNO master clock (Invited) / C. Ekstrom ... [et al.]. The transportable cesium fountain clock NIM5: its construction and performance (Invited) / T. Li ... [et al.].Compensated multi-pole merc

  20. Monolithic THz Frequency Multipliers

    NASA Technical Reports Server (NTRS)

    Erickson, N. R.; Narayanan, G.; Grosslein, R. M.; Martin, S.; Mehdi, I.; Smith, P.; Coulomb, M.; DeMartinez, G.

    2001-01-01

    Frequency multipliers are required as local oscillator sources for frequencies up to 2.7 THz for FIRST and airborne applications. Multipliers at these frequencies have not previously been demonstrated, and the object of this work was to show whether such circuits are really practical. A practical circuit is one which not only performs as well as is required, but also can be replicated in a time that is feasible. As the frequency of circuits is increased, the difficulties in fabrication and assembly increase rapidly. Building all of the circuit on GaAs as a monolithic circuit is highly desirable to minimize the complexity of assembly, but at the highest frequencies, even a complete monolithic circuit is extremely small, and presents serious handling difficulty. This is compounded by the requirement for a very thin substrate. Assembly can become very difficult because of handling problems and critical placement. It is very desirable to make the chip big enough to that it can be seen without magnification, and strong enough that it may be picked up with tweezers. Machined blocks to house the chips present an additional challenge. Blocks with complex features are very expensive, and these also imply very critical assembly of the parts. It would be much better if the features in the block were as simple as possible and non-critical to the function of the chip. In particular, grounding and other electrical interfaces should be done in a manner that is highly reproducible.

  1. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Lang, Robert J. (Inventor)

    2001-01-01

    Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  2. Hg(+) Frequency Standards

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  3. Frequency Tunable Wire Lasers

    NASA Technical Reports Server (NTRS)

    Hu, Qing (Inventor)

    2013-01-01

    The present invention provides frequency tunable solid-state radiation-generating devices, such as lasers and amplifiers, whose active medium has a size in at least one transverse dimension (e.g., its width) that is much smaller than the wavelength of radiation generated and/or amplified within the active medium. In such devices, a fraction of radiation travels as an evanescent propagating mode outside the active medium. It has been discovered that in such devices the radiation frequency can be tuned by the interaction of a tuning mechanism with the propagating evanescent mode.

  4. Dual frequency optical cavity

    DOEpatents

    George, E. Victor (Livermore, CA); Schipper, John F. (Palo Alto, CA)

    1985-01-01

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a "T" configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  5. All-frequency reflectionlessness

    E-print Network

    Philbin, T G

    2015-01-01

    We derive planar permittivity profiles that do not reflect perpendicularly exiting radiation of any frequency. The materials obey the Kramers-Kronig relations and have no regions of gain. Reduction of the Casimir force by means of such materials is also discussed.

  6. All-frequency reflectionlessness

    E-print Network

    T. G. Philbin

    2015-10-10

    We derive planar permittivity profiles that do not reflect perpendicularly exiting radiation of any frequency. The materials obey the Kramers-Kronig relations and have no regions of gain. Reduction of the Casimir force by means of such materials is also discussed.

  7. Fiber optic frequency transfer link

    NASA Technical Reports Server (NTRS)

    Primas, Lori E. (inventor); Sydnor, Richard L. (inventor); Lutes, George F. (inventor)

    1991-01-01

    A reference frequency distribution system is disclosed for transmitting a reference frequency from a reference unit to a remote unit while keeping the reference frequency at the reference unit and the remote unit in phase. A fiber optic cable connects the reference unit to the remote unit. A frequency source at the reference unit produces a reference frequency having an adjustable phase. A fiber optic transmitter at the reference unit modulates a light beam with the reference frequency and transmits the light beam into the fiber optic cable. A 50/50 reflector at the remote unit reflects a first portion of the light beam from the reference unit back into the fiber optic cable to the reference unit. A first fiber optic receiver disposed at the remote unit receives a second portion of the light beam and demodulates the reference frequency to be used at the remote unit. A second fiber optic receiver disposed at the reference unit receives the first portion of the light beam and demodulates a reference frequency component. A phase conjugator is connected to the frequency source for comparing the phase of the reference frequency component to the phase of the reference frequency modulating the light beam being transmitted from the reference unit to maintain a conjugate (anti-symmetric) relationship between the reference frequency component and the reference frequency modulating the light beam where virtually no phase difference exists between the phase of the reference frequency component and the phase of the reference frequency modulating the light beam.

  8. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers. PMID:26072834

  9. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  10. High frequency reference electrode

    DOEpatents

    Kronberg, James W. (Aiken, SC)

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  11. Extended frequency turbofan model

    NASA Technical Reports Server (NTRS)

    Mason, J. R.; Park, J. W.; Jaekel, R. F.

    1980-01-01

    The fan model was developed using two dimensional modeling techniques to add dynamic radial coupling between the core stream and the bypass stream of the fan. When incorporated into a complete TF-30 engine simulation, the fan model greatly improved compression system frequency response to planar inlet pressure disturbances up to 100 Hz. The improved simulation also matched engine stability limits at 15 Hz, whereas the one dimensional fan model required twice the inlet pressure amplitude to stall the simulation. With verification of the two dimensional fan model, this program formulated a high frequency F-100(3) engine simulation using row by row compression system characteristics. In addition to the F-100(3) remote splitter fan, the program modified the model fan characteristics to simulate a proximate splitter version of the F-100(3) engine.

  12. Variable Frequency Pump Drives 

    E-print Network

    Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

    1986-01-01

    depends upon the pump/system characteristics, the range of operating flows and . the duration of "off design" operation. This aspect of variable speed drive is fundamental to any evaluation; Fuchs[l] and Humphrey[2] are two who have addressed itin... and their application. The fundamentals of variable speed centrifugal pump operation are reviewed, then the advantages and evaluation approaches peculiar to variable frequency drive outlined. In addition to the immediate advantages available with existing pumps...

  13. Multiwire thermocouples: Frequency response

    NASA Technical Reports Server (NTRS)

    Forney, L. J.; Fralick, G. C.

    1994-01-01

    Experimental measurements are made with a novel two wire thermocouple. Signals from two wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the two wire thermocouple requires no compensation for omega less than or equal to 2 omega(sub 1) where omega is the natural frequency of the smaller wire. A compensation factor is recommended for larger frequencies omega greater than 2 omega(sub 1). Theory and experimental measurements are compared with a novel three wire thermocouple. Signals from three wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three wire thermocouple requires no compensation for omega less than or equal to 5 omega(sub 1) where omega (sub 1) is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter. Measurements are recorded for multiwire thermocouples consisting of either two or three wires of unequal diameters. Signals from the multiwire probe are recorded for a reversing gas flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the multiwire thermocouple requires no compensation provided omega/omega(sub 1) is less than 2.3 for two wires or omega/omega(sub 1) is less than 3.6 for three wires where omega(sub 1) is the natural frequency of the smaller wire based on the maximum gas velocity. The latter results were possible provided Fourier transformed data were used and knowledge of the gas velocity is available.

  14. Rapid frequency scan EPR.

    PubMed

    Tseitlin, Mark; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2011-08-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5T(2) after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5T(2). However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5T(2), even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B(1), periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. PMID:21664848

  15. Rapid frequency scan EPR

    NASA Astrophysics Data System (ADS)

    Tseitlin, Mark; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2011-08-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5 T2 after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5 T2. However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5 T2, even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B1, periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation.

  16. Frequency stabilisation of femtosecond frequency combs with a reference laser

    SciTech Connect

    Bagayev, S N; Pivtsov, V S; Zheltikov, Aleksei M

    2002-04-30

    A solution to the key problem of femtosecond metrology - elimination of the frequency offset related to the intracavity dispersion of a femtosecond laser - is proposed. The proposed method involves stabilisation of the intermode interval between equidistant spectral components in a frequency comb produced by a mode-locked femtosecond laser by phase-locking the frequency difference between a pair of discrete spectral components in this comb to the frequency of a reference laser. An introduction of a nonlinear-optical crystal for frequency doubling into the scheme for frequency-comb stabilisation allows the frequency offset related to the intracavity dispersion of the femtosecond laser to be eliminated, thus suggesting the way for absolute stabilisation of frequency combs generated by femtosecond mode-locked lasers. Radiation of a reference laser with such an approach plays the role of an anchor in the femtosecond clockwork. (control of laser radiation parameters)

  17. Impacts of frequency increment errors on frequency diverse array beampattern

    NASA Astrophysics Data System (ADS)

    Gao, Kuandong; Chen, Hui; Shao, Huaizong; Cai, Jingye; Wang, Wen-Qin

    2015-12-01

    Different from conventional phased array, which provides only angle-dependent beampattern, frequency diverse array (FDA) employs a small frequency increment across the antenna elements and thus results in a range angle-dependent beampattern. However, due to imperfect electronic devices, it is difficult to ensure accurate frequency increments, and consequently, the array performance will be degraded by unavoidable frequency increment errors. In this paper, we investigate the impacts of frequency increment errors on FDA beampattern. We derive the beampattern errors caused by deterministic frequency increment errors. For stochastic frequency increment errors, the corresponding upper and lower bounds of FDA beampattern error are derived. They are verified by numerical results. Furthermore, the statistical characteristics of FDA beampattern with random frequency increment errors, which obey Gaussian distribution and uniform distribution, are also investigated.

  18. 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.

  19. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1989-10-24

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a harmonic generating unit which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L- arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  20. SECURING RADIO FREQUENCY IDENTIFICATION (RFID)

    E-print Network

    May 2007 SECURING RADIO FREQUENCY IDENTIFICATION (RFID) SYSTEMS SECURING RADIO FREQUENCY IDENTIFICATION (RFID) SYSTEMS Karen Scarfone, EditorKaren Scarfone, Editor Computer Security Division of Standards and Technology National Institute of Standards and Technology RFID is a form of automatic

  1. Time, Frequency and Physical Measurement.

    ERIC Educational Resources Information Center

    Hellwig, Helmut; And Others

    1978-01-01

    Describes several developments in atomic clocks and frequency standards pointing out the feasibility and practicality in adopting a unified standard of time and frequency to replace other base standards of length, mass, and temperature. (GA)

  2. High-frequency ECG

    NASA Technical Reports Server (NTRS)

    Tragardh, Elin; Schlegel, Todd T.

    2006-01-01

    The standard ECG is by convention limited to 0.05-150 Hz, but higher frequencies are also present in the ECG signal. With high-resolution technology, it is possible to record and analyze these higher frequencies. The highest amplitudes of the high-frequency components are found within the QRS complex. In past years, the term "high frequency", "high fidelity", and "wideband electrocardiography" have been used by several investigators to refer to the process of recording ECGs with an extended bandwidth of up to 1000 Hz. Several investigators have tried to analyze HF-QRS with the hope that additional features seen in the QRS complex would provide information enhancing the diagnostic value of the ECG. The development of computerized ECG-recording devices that made it possible to record ECG signals with high resolution in both time and amplitude, as well as better possibilities to store and process the signals digitally, offered new methods for analysis. Different techniques to extract the HF-QRS have been described. Several bandwidths and filter types have been applied for the extraction as well as different signal-averaging techniques for noise reduction. There is no standard method for acquiring and quantifying HF-QRS. The physiological mechanisms underlying HF-QRS are still not fully understood. One theory is that HF-QRS are related to the conduction velocity and the fragmentation of the depolarization wave in the myocardium. In a three-dimensional model of the ventricles with a fractal conduction system it was shown that high numbers of splitting branches are associated with HF-QRS. In this experiment, it was also shown that the changes seen in HF-QRS in patients with myocardial ischemia might be due to the slowing of the conduction velocity in the region of ischemia. This mechanism has been tested by Watanabe et al by infusing sodium channel blockers into the left anterior descending artery in dogs. In their study, 60 unipolar ECGs were recorded from the entire ventricular surface and were signal-averaged and filtered in the 30-250 Hz frequency range. The results showed that the decrease noted in the HF-QRS correlated linearly with the local conduction delay. The results suggest that HF-QRS is a potent indicator of disturbed local conduction. An alternative theory is that HF-QRS reflect the shape of the original electrocardiographic signal. Bennhagen et al showed that root mean square (RMS) voltage values of the depolarization signal correlate poorly with the signal amplitude but highly with the first and second derivatives, i.e. the velocity and the acceleration of the signal. It has also been suggested that the autonomic nervous system affects HF-QRS. For example, sitting up causes significant changes in HF-QRS in some leads compared to the supine position [Douglas et al., 2006]. Unpublished results indicate that familial dysautonomic patients (both vagal and sympathetic degeneration) have very little Reduced Amplitude Zones (RAZ) formation . Athletic individuals, especially elite athletes, who have vagally-mediated changes on the conventional ECG (i.e. early repolarization, bradycardia) have increased RAZ formation. Further electrophysiological studies are needed, however, to better understand the underlying mechanisms of HF-QRS. Several investigators have studied HF-QRS in different cardiac conditions, including acute myocardial ischemia and myocardial infarction (MI). However, in order for clinicians to confidently use HF-QRS as an adjunct to standard ECG, more knowledge about the characteristics of HF-QRS is needed.

  3. Frequency-bin entangled photons

    SciTech Connect

    Olislager, L.; Emplit, P.; Nguyen, A. T.; Massar, S.; Merolla, J.-M.; Huy, K. Phan

    2010-07-15

    A monochromatic laser pumping a parametric down-conversion crystal generates frequency-entangled photon pairs. We study this experimentally by addressing such frequency-entangled photons at telecommunication wavelengths (around 1550 nm) with fiber-optics components such as electro-optic phase modulators and narrow-band frequency filters. The theory underlying our approach uses the notion of frequency-bin entanglement. Our results show that the phase modulators address coherently up to eleven frequency bins, leading to an interference pattern which can violate by more than five standard deviations a Bell inequality adapted to our setup.

  4. High frequency nanotube oscillator

    DOEpatents

    Peng, Haibing (Houston, TX); Zettl, Alexander K. (Kensington, TX)

    2012-02-21

    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  5. Flying radio frequency undulator

    SciTech Connect

    Kuzikov, S. V.; Vikharev, A. A.; Savilov, A. V.

    2014-07-21

    A concept for the room-temperature rf undulator, designed to produce coherent X-ray radiation by means of a relatively low-energy electron beam and pulsed mm-wavelength radiation, is proposed. The “flying” undulator is a high-power short rf pulse co-propagating together with a relativistic electron bunch in a helically corrugated waveguide. The electrons wiggle in the rf field of the ?1st spatial harmonic with the phase velocity directed in the opposite direction in respect to the bunch velocity, so that particles can irradiate high-frequency Compton's photons. A high group velocity (close to the speed of light) ensures long cooperative motion of the particles and the co-propagating rf pulse.

  6. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1988-08-15

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a harmonic generating unit'' which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyle hydroxyyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  7. Frequency mixing crystal

    DOEpatents

    Ebbers, Christopher A. (Livermore, CA); Davis, Laura E. (Manteca, CA); Webb, Mark (Salida, CA)

    1992-01-01

    In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

  8. Flying radio frequency undulator

    NASA Astrophysics Data System (ADS)

    Kuzikov, S. V.; Savilov, A. V.; Vikharev, A. A.

    2014-07-01

    A concept for the room-temperature rf undulator, designed to produce coherent X-ray radiation by means of a relatively low-energy electron beam and pulsed mm-wavelength radiation, is proposed. The "flying" undulator is a high-power short rf pulse co-propagating together with a relativistic electron bunch in a helically corrugated waveguide. The electrons wiggle in the rf field of the -1st spatial harmonic with the phase velocity directed in the opposite direction in respect to the bunch velocity, so that particles can irradiate high-frequency Compton's photons. A high group velocity (close to the speed of light) ensures long cooperative motion of the particles and the co-propagating rf pulse.

  9. Frequency doubling crystals

    DOEpatents

    Wang, Francis (Danville, CA); Velsko, Stephan P. (Livermore, CA)

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  10. Radio frequency coaxial feedthrough

    DOEpatents

    Owens, Thomas L. (Kingston, TN)

    1989-01-17

    An improved radio frequency coaxial transmission line vacuum feed-through provided based on the use of a half-wavelength annular dielectric pressure barrier disk, or multiple disks comprising an effective half wavelength structure to eliminate reflections from the barrier surfaces. Gas-tight seals are formed about the outer and inner diameter surfaces of the barrier disk using a sealing technique which generates radial forces sufficient to form seals by forcing the conductor walls against the surfaces of the barrier disks in a manner which does not deform the radii of the inner and outer conductors, thereby preventing enhancement of the electric field at the barrier faces which limits voltage and power handling capabilities of a feedthrough.

  11. Mid-infrared frequency combs

    E-print Network

    Schliesser, Albert; Hänsch, Theodor W

    2012-01-01

    Laser frequency combs are coherent light sources that emit a broad spectrum consisting of discrete, evenly spaced narrow lines, each having an absolute frequency measurable within the accuracy of an atomic clock. Their development, a decade ago, in the near-infrared and visible domains has revolutionized frequency metrology with numerous windfalls into other fields such as astronomy or attosecond science. Extension of frequency comb techniques to the mid-infrared spectral region is now under exploration. Versatile mid-infrared frequency comb generators, based on novel laser gain media, nonlinear frequency conversion or microresonators, promise to significantly expand the tree of applications of frequency combs. In particular, novel approaches to molecular spectroscopy in the fingerprint region, with dramatically improved precision, sensitivity, recording time and/or spectral bandwidth may spark off new discoveries in the various fields relevant to molecular sciences.

  12. High spectral purity Kerr frequency comb radio frequency photonic oscillator

    NASA Astrophysics Data System (ADS)

    Liang, W.; Eliyahu, D.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-08-01

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than -60 dBc Hz-1 at 10 Hz, -90 dBc Hz-1 at 100 Hz and -170 dBc Hz-1 at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10-10 at 1-100 s integration time--orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption.

  13. High spectral purity Kerr frequency comb radio frequency photonic oscillator.

    PubMed

    Liang, W; Eliyahu, D; Ilchenko, V S; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2015-01-01

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10?GHz radio frequency photonic oscillator characterized with phase noise better than -60?dBc?Hz(-1) at 10?Hz, -90?dBc?Hz(-1) at 100?Hz and -170?dBc?Hz(-1) at 10?MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10(-10) at 1-100?s integration time-orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption. PMID:26260955

  14. Operational frequency stability of rubidium and cesium frequency standards

    NASA Technical Reports Server (NTRS)

    Lavery, J. E.

    1973-01-01

    The frequency stabilities under operational conditions of several commercially available rubidium and cesium frequency standards were determined from experimental data for frequency averaging times from 10 to the 7th power s and are presented in table and graph form. For frequency averaging times between 10 to the 5th power and 10 to the 7th power s, the rubidium standards tested have a stability of between 10 to the minus 12th power and 5 x 10 to the minus 12th power, while the cesium standards have a stability of between 2 x 10 to the minus 13th power and 5 x 10 to the minus 13th power.

  15. Ab initio potential energy and dipole moment surfaces, infrared spectra, and vibrational predissociation dynamics of the 35Cl-⋯H2/D2 complexes

    NASA Astrophysics Data System (ADS)

    Buchachenko, A. A.; Grinev, T. A.; K?os, J.; Bieske, E. J.; Szcz??niak, M. M.; Cha?asi?ski, G.

    2003-12-01

    Three-dimensional potential energy and dipole moment surfaces of the Cl--H2 system are calculated ab initio by means of a coupled cluster method with single and double excitations and noniterative correction to triple excitations with augmented correlation consistent quadruple-zeta basis set supplemented with bond functions, and represented in analytical forms. Variational calculations of the energy levels up to the total angular momentum J=25 provide accurate estimations of the measured rotational spectroscopic constants of the ground van der Waals levels n=0 of the Cl-⋯H2/D2 complexes although they underestimate the red shifts of the mid-infrared spectra with v=0?v=1 vibrational excitation of the monomer. They also attest to the accuracy of effective radial interaction potentials extracted previously from experimental data using the rotational RKR procedure. Vibrational predissociation of the Cl-⋯H2/D2(v=1) complexes is shown to follow near-resonant vibrational-to-rotational energy transfer mechanism so that more than 97% of the product monomers are formed in the highest accessible rotational level. This mechanism explains the strong variation of the predissociation rate with isotopic content and nuclear spin form of the complex. Strong deviation of the observed relative abundances of ortho and para forms of the complexes from those of the monomers is qualitatively explained by the secondary ligand exchange reactions in the ionic beam, within the simple thermal equilibrium model. Positions and intensities of the hot v=0, n=1?v=1, n=1 and combination v=0, n=0?v=1, n=1 bands are predicted, and implications to the photoelectron spectroscopy of the complex are briefly discussed.

  16. Flood frequency in Alaska

    USGS Publications Warehouse

    Childers, J.M.

    1970-01-01

    Records of peak discharge at 183 sites were used to study flood frequency in Alaska. The vast size of Alaska, its great ranges of physiography, and the lack of data for much of the State precluded a comprehensive analysis of all flood determinants. Peak stream discharges, where gaging-station records were available, were analyzed for 2-year, 5-year, 10-year, 25-year, and 50-year average-recurrence intervals. A regional analysis of the flood characteristics by multiple-regression methods gave a set of equations that can be used to estimate floods of selected recurrence intervals up to 50 years for any site on any stream in Alaska. The equations relate floods to drainage-basin characteristics. The study indicates that in Alaska the 50-year flood can be estimated from 10-year gaging- station records with a standard error of 22 percent whereas the 50-year flood can be estimated from the regression equation with a standard error of 53 percent. Also, maximum known floods at more than 500 gaging stations and miscellaneous sites in Alaska were related to drainage-area size. An envelope curve of 500 cubic feet per second per square mile covered all but 2 floods in the State.

  17. Effective switching frequency multiplier inverter

    DOEpatents

    Su, Gui-Jia (Oak Ridge, TN); Peng, Fang Z. (Okemos, MI)

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  18. Frequency-Shift Hearing Aid

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.

    1994-01-01

    Proposed hearing aid maps spectrum of speech into band of lower frequencies at which ear remains sensitive. By redirecting normal speech frequencies into frequency band from 100 to 1,500 Hz, hearing aid allows people to understand normal conversation, including telephone calls. Principle operation of hearing aid adapted to other uses such as, clearing up noisy telephone or radio communication. In addition, loud-speakers more easily understood in presence of high background noise.

  19. Acoustic resonance frequency locked photoacoustic spectrometer

    DOEpatents

    Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

    2003-09-09

    A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell, the acoustic source having a source frequency; repeatedly and continuously sweeping the source frequency across the resonance frequency at a sweep rate; and employing an odd-harmonic of the source frequency sweep rate to maintain the source frequency sweep centered on the resonance frequency.

  20. Dual-frequency ferromagnetic resonance

    SciTech Connect

    Guan, Y.; Bailey, W.E.

    2006-05-15

    We describe a new experimental technique to investigate coupling effects between different layers or modes in ferromagnetic resonance (FMR). Dual FMR frequencies are excited (2-8 GHz) simultaneously and detected selectively in a broadband rf circuit using lock-in amplifier detection at separate modulation frequencies.

  1. Stabilized radio-frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1982-09-29

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  2. Gaming Frequency and Academic Performance

    ERIC Educational Resources Information Center

    Ip, Barry; Jacobs, Gabriel; Watkins, Alan

    2008-01-01

    There are numerous claims that playing computer and video games may be educationally beneficial, but there has been little formal investigation into whether or not the frequency of exposure to such games actually affects academic performance. This paper explores the issue by analysing the relationships between gaming frequency--measured as the…

  3. Lexical Frequency in Sign Languages

    ERIC Educational Resources Information Center

    Johnston, Trevor

    2012-01-01

    Measures of lexical frequency presuppose the existence of corpora, but true machine-readable corpora of sign languages (SLs) are only now being created. Lexical frequency ratings for SLs are needed because there has been a heavy reliance on the interpretation of results of psycholinguistic and neurolinguistic experiments in the SL research…

  4. Noncollinear Frequency Conversion Klaus Betzler

    E-print Network

    Osnabrück, Universität

    add up linearly: Two apples are twice the price of one. Klaus Betzler Noncollinear Frequency on linearity: Length, Weight, Intensity, . . . Prices usually add up linearly: Two apples are twice the price usually add up linearly: Two apples are twice the price of one. Klaus Betzler Noncollinear Frequency

  5. Signal Frequency Spectra with Audacity®

    ERIC Educational Resources Information Center

    Gailey, Alycia

    2015-01-01

    The primary objective of the activity presented here is to allow students to explore the frequency components of various simple signals, with the ultimate goal of teaching them how to remove unwanted noise from a voice signal. Analysis of the frequency components of a signal allows students to design filters that remove unwanted components of a…

  6. Hydrogen-maser frequency standard

    NASA Technical Reports Server (NTRS)

    Reinhardt, V.; Cervenka, P.

    1979-01-01

    Wall shift in frequency of proposed variable-shift maser that is caused by collisions between hydrogen atoms and container walls, could easily be determined, thereby allowing building of frequency standard with accuracy of 1 part in 10 to 14th power.

  7. Contour Integration across Spatial Frequency

    ERIC Educational Resources Information Center

    Persike, Malte; Olzak, Lynn A.; Meinhardt, Gunter

    2009-01-01

    Association field models of contour integration suggest that local band-pass elements are spatially grouped to global contours within limited bands of spatial frequency (Field, Hayes, & Hess, 1993). While results for local orientation and spacing variation render support for AF models, effects of spatial frequency (SF) have rarely been addressed.…

  8. Frequency conversion of structured light

    E-print Network

    Steinlechner, Fabian; Pruneri, Valerio; Torres, Juan P

    2015-01-01

    We demonstrate the coherent frequency conversion of structured light, optical beams in which the phase varies in each point of the transverse plane, from the near infrared (803nm) to the visible (527nm). The frequency conversion process makes use of sum-frequency generation in a periodically poled lithium niobate (ppLN) crystal with the help of a 1540-nm Gaussian pump beam. We perform far-field intensity measurements of the frequency-converted field, and verify the sought-after transformation of the characteristic intensity and phase profiles for various input modes. The coherence of the frequency-conversion process is confirmed using a mode-projection technique with a phase mask and a single-mode fiber. The presented results could be of great relevance to novel applications in high-resolution microscopy and quantum information processing.

  9. Pitch perception: dissociating frequency from fundamental-frequency discrimination.

    PubMed

    Oxenham, Andrew J; Micheyl, Christophe

    2013-01-01

    High-frequency pure tones (>6 kHz), which alone do not produce salient melodic pitch information, provide melodic pitch information when they form part of a harmonic complex tone with a lower fundamental frequency (F0). We explored this phenomenon in normal-hearing listeners by measuring F0 difference limens (F0DLs) for harmonic complex tones and pure-tone frequency difference limens (FDLs) for each of the tones within the harmonic complexes. Two spectral regions were tested. The low- and high-frequency band-pass regions comprised harmonics 6-11 of a 280- or 1,400-Hz F0, respectively; thus, for the high-frequency region, audible frequencies present were all above 7 kHz. Frequency discrimination of inharmonic log-spaced tone complexes was also tested in control conditions. All tones were presented in a background of noise to limit the detection of distortion products. As found in previous studies, F0DLs in the low region were typically no better than the FDL for each of the constituent pure tones. In contrast, F0DLs for the high-region complex were considerably better than the FDLs found for most of the constituent (high-frequency) pure tones. The data were compared with models of optimal spectral integration of information, to assess the relative influence of peripheral and more central noise in limiting performance. The results demonstrate a dissociation in the way pitch information is integrated at low and high frequencies and provide new challenges and constraints in the search for the underlying neural mechanisms of pitch. PMID:23716218

  10. Medium-Frequency Pseudonoise Georadar

    NASA Technical Reports Server (NTRS)

    Arendt, G. Dickey; Carl, J. R.; Byerly, Kent A.; Amini, B. Jon

    2005-01-01

    Ground-probing radar systems featuring medium-frequency carrier signals phase-modulated by binary pseudonoise codes have been proposed. These systems would be used to locate and detect movements of subterranean surfaces; the primary intended application is in warning of the movement of underground water toward oil-well intake ports in time to shut down those ports to avoid pumping of water. Other potential applications include oil-well logging and monitoring of underground reservoirs. A typical prior georadar system operates at a carrier frequency of at least 50 MHz in order to provide useable range resolution. This frequency is too high for adequate penetration of many underground layers of interest. On the other hand, if the carrier frequency were to be reduced greatly to increase penetration, then bandwidth and thus range resolution would also have to be reduced, thereby rendering the system less useful. The proposed medium-frequency pseudonoise georadar systems would offer the advantage of greater penetration at lower carrier frequencies, but without the loss of resolution that would be incurred by operating typical prior georadar systems at lower frequencies.

  11. Laser frequency stabilization for LISA

    NASA Technical Reports Server (NTRS)

    Mueller, Guido; McNamara, Paul; Thorpe, Ira; Camp, Jordan

    2005-01-01

    The requirement on laser frequency noise in the Laser Interferometer Space Antenna (LISA) depends on the velocity and our knowledge of the position of each spacecraft of the interferometer. Currently it is assumed that the lasers must have a pre-stabilized frequency stability of 30Hz/square root of Hz over LISA'S most sensitive frequency band (3 mHz - 30 mHz). The intrinsic frequency stability of even the most stable com- mercial lasers is several orders of magnitude above this level. Therefore it is necessary to stabilize the laser frequency to an ultra-stable frequency reference which meets the LISA requirements. The baseline frequency reference for the LISA lasers are high finesse optical cavities based on ULE spacers. We measured the stability of two ULE spacer cavities with respect to each other. Our current best results show a noise floor at, or below, 30 Hz/square root of Hz above 3 mHz. In this report we describe the experimental layout of the entire experiment and discuss the limiting noise sources.

  12. Pulsed optically pumped frequency standard

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2004-08-01

    We reconsider the idea of a pulsed optically pumped frequency standard conceived in the early 1960s to eliminate the light-shift effect. The development of semiconductor lasers and of pulsed electronic techniques for atomic fountains and new theoretical findings allow an implementation of this idea which may lead to a frequency standard whose frequency stability is limited only by the thermal noise in the short term and by the temperature drift in the long term. We shall also show both theoretically and experimentally the possibility of doubling the atomic quality factor with respect to the classical Ramsey technique approach.

  13. Parametric Effects of Word Frequency in Memory for Mixed Frequency Lists

    ERIC Educational Resources Information Center

    Lohnas, Lynn J.; Kahana, Michael J.

    2013-01-01

    The "word frequency paradox" refers to the finding that low frequency words are better recognized than high frequency words yet high frequency words are better recalled than low frequency words. Rather than comparing separate groups of low and high frequency words, we sought to quantify the functional relation between word frequency and…

  14. Estimations of uncertainties of frequencies

    NASA Astrophysics Data System (ADS)

    Eyer, Laurent; Nicoletti, Jean-Marc; Morgenthaler, Stephan

    2015-08-01

    Diverse variable phenomena in the Universe are periodic. Astonishingly many of the periodic signals present in stars have timescales coinciding with human ones (from minutes to years). The periods of signals often have to be deduced from time series which are irregularly sampled and sparse, furthermore correlations between the brightness measurements and their estimated uncertainties are common.The uncertainty on the frequency estimation is reviewed. We explore the astronomical and statistical literature, in both cases of regular and irregular samplings. The frequency uncertainty is depending on signal to noise ratio, the frequency, the observational timespan. The shape of the light curve should also intervene, since sharp features such as exoplanet transits, stellar eclipses, raising branches of pulsation stars give stringent constraints.We propose several procedures (parametric and nonparametric) to estimate the uncertainty on the frequency which are subsequently tested against simulated data to assess their performances.

  15. Dual-frequency microwave antenna

    NASA Technical Reports Server (NTRS)

    Bathker, D. A.; Brunstein, S. A.; Ludwig, A. C.; Potter, P. D.

    1980-01-01

    Single antenna using two feed horns (one for receiving and radiation X-band signals, and one for S-band signals), in conjunction with ellipsoid reflector and dichronic plate, can accommodate two different frequencies simultaneously.

  16. AUTO ID FUTURE - FREQUENCY AGNOSTIC

    E-print Network

    DATTA, SHOUMEN

    Identification of information is one key to the development of intelligent decision systems of the future. Frequency agnostic automatic identification is only one step in the physical world to make physical objects identify ...

  17. Frequency coded sensors incorporating tapers

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor)

    2010-01-01

    A surface acoustic wave device includes a piezoelectric substrate on which is formed a transducer that generates acoustic waves on the surface of the substrate from electrical waves received by the transducer. The waves are carried along an acoustic track to either a second transducer or a reflector. The transducers or transducer and reflector are formed of subsections that are constructed to operate at mutually different frequencies. The subsections of at least one of the transducers or transducer and reflector are out of alignment with respect to one another relative to the transverse of the propagation direction. The out of aligned subsections provide not only a frequency component but also a time to the signal output signal. Frequency response characteristics are improved. An alternative embodiment provides that the transducers and/or reflectors are continuously tapered instead of having discrete frequency subsections.

  18. High Frequency Electronic Packaging Technology

    NASA Technical Reports Server (NTRS)

    Herman, M.; Lowry, L.; Lee, K.; Kolawa, E.; Tulintseff, A.; Shalkhauser, K.; Whitaker, J.; Piket-May, M.

    1994-01-01

    Commercial and government communication, radar, and information systems face the challenge of cost and mass reduction via the application of advanced packaging technology. A majority of both government and industry support has been focused on low frequency digital electronics.

  19. Frequency regulator for synchronous generators

    DOEpatents

    Karlicek, Robert F. (1920 Camino Centroloma, Fullerton, CA 92633)

    1982-01-01

    The present invention is directed to a novel frequency regulator which controls a generator output frequency for variations in both the input power to the generator and the power supplied to an uncontrolled external load. The present invention further includes over current and current balance protection devices which are relatively inexpensive to manufacture, which may be encapsulated to provide protection from the operating environment and which respond more quickly than previously known electromechanical devices.

  20. The classical microwave frequency standards

    NASA Technical Reports Server (NTRS)

    Busca, Giovanni; Thomann, Pierre; Laurent-Guy, Bernier; Willemin, Philippe; Schweda, Hartmut S.

    1990-01-01

    Some key problems are presented encountered in the classical microwave frequency standards which are still not solved today. The point of view expressed benefits from the experience gained both in the industry and in the research lab, on the following classical microwave frequency standards: active and passive H, conventional and laser pumped Cs beam tube, small conventional and laser pumped Rubidium. The accent is put on the Rubidium standard.

  1. Frequency regulator for synchronous generators

    DOEpatents

    Karlicek, R.F.

    1982-08-10

    The present invention is directed to a novel frequency regulator which controls a generator output frequency for variations in both the input power to the generator and the power supplied to an uncontrolled external load. The present invention further includes over current and current balance protection devices which are relatively inexpensive to manufacture, which may be encapsulated to provide protection from the operating environment and which respond more quickly than previously known electromechanical devices. 11 figs.

  2. Stepped frequency ground penetrating radar

    DOEpatents

    Vadnais, Kenneth G. (Ojai, CA); Bashforth, Michael B. (Buellton, CA); Lewallen, Tricia S. (Ventura, CA); Nammath, Sharyn R. (Santa Barbara, CA)

    1994-01-01

    A stepped frequency ground penetrating radar system is described comprising an RF signal generating section capable of producing stepped frequency signals in spaced and equal increments of time and frequency over a preselected bandwidth which serves as a common RF signal source for both a transmit portion and a receive portion of the system. In the transmit portion of the system the signal is processed into in-phase and quadrature signals which are then amplified and then transmitted toward a target. The reflected signals from the target are then received by a receive antenna and mixed with a reference signal from the common RF signal source in a mixer whose output is then fed through a low pass filter. The DC output, after amplification and demodulation, is digitized and converted into a frequency domain signal by a Fast Fourier Transform. A plot of the frequency domain signals from all of the stepped frequencies broadcast toward and received from the target yields information concerning the range (distance) and cross section (size) of the target.

  3. Detecting body cavity bombs with nuclear quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Collins, Michael London

    Nuclear Quadrupole Resonance (NQR) is a technology with great potential for detecting hidden explosives. Past NQR research has studied the detection of land mines and bombs concealed within luggage and packages. This thesis focuses on an NQR application that has received less attention and little or no publicly available research: detecting body cavity bombs (BCBs). BCBs include explosives that have been ingested, inserted into orifices, or surgically implanted. BCBs present a threat to aviation and secure facilities. They are extremely difficult to detect with the technology currently employed at security checkpoints. To evaluate whether or not NQR can be used to detect BCBs, a computational model is developed to assess how the dielectric properties of biological tissue affect the radio frequency magnetic field employed in NQR (0.5-5MHz). The relative permittivity of some biological tissue is very high (over 1,000 at 1MHz), making it conceivable that there is a significant effect on the electromagnetic field. To study this effect, the low-frequency approximation known as the Darwin model is employed. First, the electromagnetic field of a coil is calculated in free space. Second, a dielectric object or set of objects is introduced, and the free-space electric field is modified to accommodate the dielectric object ensuring that the relevant boundary conditions are obeyed. Finally, the magnetic field associated with the corrected electric field is calculated. This corrected magnetic field is evaluated with an NQR simulation to estimate the impact of dielectric tissue on NQR measurements. The effect of dielectric tissue is shown to be small, thus obviating a potential barrier to BCB detection. The NQR model presented may assist those designing excitation and detection coils for NQR. Some general coil design considerations and strategies are discussed.

  4. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...transmitter. (e) Frequencies available for differential GPS stations. Frequencies in the 112-118 MHz band may be...Special Category I (SCAT-I) ground stations for differential GPS data links. (1) The frequencies available are...

  5. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...transmitter. (e) Frequencies available for differential GPS stations. Frequencies in the 112-118 MHz band may be...Special Category I (SCAT-I) ground stations for differential GPS data links. (1) The frequencies available are...

  6. Dual-frequency multifunction lidar

    NASA Astrophysics Data System (ADS)

    Diaz, Rosemary; Chan, Sze-Chun; Liu, Jia-Ming

    2007-02-01

    The design and performance of a multifunction continuous wave dual-frequency lidar system is presented. The system is based on the use of the nonlinear dynamics of an optically injected semiconductor laser. Under proper operating conditions, the laser emits a dual-frequency beam with a broadly tunable microwave separation. The two optical lines are coherently locked to each other using an external microwave synthesizer, resulting in a stable microwave beat frequency. The lidar system is capable of simultaneous velocity and range measurement of remote targets. The velocity is measured from the Doppler shift of the microwave beat frequency. The stability of the microwave beat frequency enables accurate measurement of low velocities. In addition, the stable locking enables long-range measurements because of the long microwave coherence length. Ranging is accomplished by extracting the time-of-flight information carried on the residual microwave phase noise. We demonstrate preliminary measurements of velocities as low as 26 ?m/s and range measurements of 7.95 km with 2 % accuracy.

  7. Quantum Cascade Laser Frequency Combs

    E-print Network

    Faist, Jérôme; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the fir...

  8. Active Faraday optical frequency standard.

    PubMed

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 ?W. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks. PMID:25361349

  9. Optimal filtering in multipulse sequences for nuclear quadrupole resonance detection

    NASA Astrophysics Data System (ADS)

    Osokin, D. Ya.; Khusnutdinov, R. R.; Mozzhukhin, G. V.; Rameev, B. Z.

    2014-05-01

    The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal.

  10. Frequency translation method for low frequency variable gain amplification and filtering

    E-print Network

    Feng, Mabel Y

    2007-01-01

    This thesis discusses an innovative solution to an industry challenge. A frequency translation method is designed to shift low frequency signals to intermediate frequencies in order to utilize higher-frequency components. ...

  11. 75 FR 81284 - Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology; Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-27

    ...Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology...Nationwide Use of High Frequency (HF) and Ultra High Frequency (UHF) Sound Navigation...for environmental disasters such as the Deepwater Horizon oil spill, SONAR equipment...

  12. 78 FR 70567 - Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology; Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-26

    ...Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology...Nationwide Use of High Frequency (HF) and Ultra High Frequency (UHF) Sound Navigation...for environmental disasters such as the Deepwater Horizon oil spill, SONAR equipment...

  13. Swept Frequency Laser Metrology System

    NASA Technical Reports Server (NTRS)

    Zhao, Feng (Inventor)

    2010-01-01

    A swept frequency laser ranging system having sub-micron accuracy that employs multiple common-path heterodyne interferometers, one coupled to a calibrated delay-line for use as an absolute reference for the ranging system. An exemplary embodiment uses two laser heterodyne interferometers to create two laser beams at two different frequencies to measure distance and motions of target(s). Heterodyne fringes generated from reflections off a reference fiducial X(sub R) and measurement (or target) fiducial X(sub M) are reflected back and are then detected by photodiodes. The measured phase changes Delta phi(sub R) and Delta phi (sub m) resulting from the laser frequency swept gives target position. The reference delay-line is the only absolute reference needed in the metrology system and this provides an ultra-stable reference and simple/economical system.

  14. Atomic frequency standards at NICT

    NASA Astrophysics Data System (ADS)

    Ido, T.; Fujieda, M.; Hachisu, H.; Hayasaka, K.; Kajita, M.; Kojima, R.; Kumagai, M.; Locke, C.; Li, Y.; Matsubara, K.; Nogami, A.; Shiga, N.; Yamaguchi, A.; Koyama, Y.; Hosokawa, M.; Hanado, Y.

    2011-10-01

    Various activities of atomic frequency standards studied in National Institute of Information and Communications Technology (NICT) are briefly reviewed. After BIPM accepted the first cesium fountain clock in NICT as a reference to determine International Atomic Time (TAI), efforts to further reduce the uncertainty of collision shifts are ongoing. A second fountain clock using atomic molasses is being built to enable the operation with less atomic density. Single ion clock using calcium has been pursued for several years in NICT. The absolute frequency measured in 2008 has CIPM to adopt the Ca+ clock transition as a part of the list of radiation (LoR) to realize the meter. Sr lattice clock has started its operation last year. The absolute frequency agreed well with those obtained in other institutes. Study of stable cavities to stabilize clock lasers are also introduced.

  15. Variable frequency microwave heating apparatus

    DOEpatents

    Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN); Johnson, Arvid C. (Lake in the Hills, IL); Thigpen, Larry T. (Angier, NC)

    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).

  16. The instantaneous frequency rate spectrogram

    NASA Astrophysics Data System (ADS)

    Czarnecki, Krzysztof

    2016-01-01

    An accelerogram of the instantaneous phase of signal components referred to as an instantaneous frequency rate spectrogram (IFRS) is presented as a joint time-frequency distribution. The distribution is directly obtained by processing the short-time Fourier transform (STFT) locally. A novel approach to amplitude demodulation based upon the reassignment method is introduced as a useful by-product. Additionally, an estimator of energy density versus the instantaneous frequency rate (IFR) is proposed and referred to as the IFR profile. The energy density is estimated based upon both the classical energy spectrogram and the IFRS smoothened by the median filter. Moreover, the impact of an analyzing window width, additive white Gaussian noise and observation time is tested. Finally, the introduced method is used for the analysis of the acoustic emission of an automotive engine. The recording of the engine of a Lamborghini Gallardo is analyzed as an example.

  17. Electron collision frequency in plasmas

    SciTech Connect

    Boercker, D.B.; Rogers, F.J.; DeWitt, H.E.

    1982-03-01

    In strongly coupled, degenerate plasmas, the electron collision frequency has been described by the Ziman formula with the ion-ion correlations modeled by the classical one-component plasma (OCP). However, this model fails to reproduce the correct quantum Lenard-Balescu result in the weak-coupling limit. It is demonstrated here that a recently obtained, correlation-function expression for the collision frequency reduces to the Ziman and Lenard-Balescu results in the appropriate limits. In addition, it is shown that an extension of the Lenard-Balescu result to include strong coupling can be interpreted as the Ziman collision frequency with the OCP structure factor replaced by the ion-ion structure factor for a two-component system. Numerical estimates of this structure factor are used to calculate the electrical conductivity in moderately coupled (GAMMA< or =2) hydrogen plasmas.

  18. Measurement method of frequency agile radar synthesis detection unit's frequency tracking accuracy

    NASA Astrophysics Data System (ADS)

    Han, Jianhui; Jiang, Yonghua

    2005-11-01

    Frequency agile radar synthesis detection unit works in frequency hopping state in radio frequency (RF) band. For the limitation of the accuracy of instantaneous frequency measurement (IFM) technology, the frequency tracking accuracy can't be examined directly. The system design method proposed by the paper examines the frequency tracking accuracy of the frequency agile radar synthesis detection unit (FARSDU) at intermediate frequency. The method is realized in engineering and good performance has been got.

  19. Surface Acoustic Wave Frequency Comb

    E-print Network

    Savchenkov, A A; Ilchenko, V S; Seidel, D; Maleki, L

    2011-01-01

    We report on realization of an efficient triply-resonant coupling between two long lived optical modes and a high frequency surface acoustic wave (SAW) mode of the same monolithic crystalline whispering gallery mode resonator. The coupling results in an opto-mechanical oscillation and generation of a monochromatic SAW. A strong nonlinear interaction of this mechanical mode with other equidistant SAW modes leads to mechanical hyper-parametric oscillation and generation of a SAW pulse train and associated frequency comb in the resonator. We visualized the comb observing the modulation of the modulated light escaping the resonator.

  20. Bichromatically pumped microresonator frequency combs

    NASA Astrophysics Data System (ADS)

    Hansson, T.; Wabnitz, S.

    2014-07-01

    A study is made of the nonlinear dynamics of bichromatically pumped microresonator Kerr frequency combs described by a driven and damped nonlinear Schrödinger equation, with an additional degree of freedom in the form of the modulation frequency. A truncated four-wave model is derived for the pump modes and the dominant sideband pair, which is found to be able to describe much of the essential dynamical behavior of the full equation. The stability of stationary states within the four-wave model is investigated, and numerical simulations are made to demonstrate that a large range of solutions, including cavity solitons, are possible beyond previously considered low-intensity patterns.

  1. Power enhanced frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Lang, Robert J. (Inventor); Waarts, Robert G. (Inventor)

    2001-01-01

    A frequency conversion system includes at least one source providing a first near-IR wavelength output including a gain medium for providing high power amplification, such as double clad fiber amplifier, a double clad fiber laser or a semiconductor tapered amplifier to enhance the power output level of the near-IR wavelength output. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Ra-man/Brillouin amplifier or oscillator between the high power source and the NFM device.

  2. Introduction to quartz frequency standards

    NASA Astrophysics Data System (ADS)

    Vig, John R.

    1992-03-01

    The fundamentals of quartz frequency standards are reviewed. The subjects discussed include: crystal resonators and oscillators, oscillator types, and the characteristics arid limitations of temperature-compensated crystal oscillators (TCXO) and oven-controlled crystal oscillators (OCXO). The oscillator instabilities discussed include: aging, noise, frequency vs. temperature, warmup, acceleration effects, magnetic field effects, atmospheric pressure effects, radiation effects, and interactions among the various effects. Guidelines are provided for oscillator comparison and selection. Discussions of specifications are also included, as are references and suggestions for further reading.

  3. DOA estimation exploiting coprime frequencies

    NASA Astrophysics Data System (ADS)

    Qin, Si; Zhang, Yimin D.; Amin, Moeness G.

    2014-05-01

    Coprime array, which utilizes a coprime pair of uniform linear subarrays, is an attractive structure to achieve sparse array configurations. Alternatively, effective coprime array configurations can be implemented using a uniform linear array with two coprime sensing frequencies. This enables the integration of the coprime array and filter concepts to achieve high capabilities in meeting system performance and complexity constraints. This paper examines its performance for direction-of-arrival estimations. In particular, we analyze the number of detectable signals and the estimation accuracy as related to the array configurations and sensing frequencies.

  4. Frequency discrimination of brief tonal steps as a function of frequency in the lesser bulldog bat.

    PubMed

    Roverud, R C

    1999-09-01

    In a two-alternative, forced-choice task lesser bulldog bats were trained to distinguish between a pure tone pulse and a pulse composed of a series of brief tonal steps oscillating between two different frequencies. The tone-step pulse gradually approximates the pure tone pulse as the frequency difference between the steps becomes progressively smaller. Frequency difference limens for the brief tonal frequency steps were determined for a broad range of ultrasonic frequencies. The variation in tone-step difference limens with frequency appears to be correlated to the frequency structure of the bat's short-constant-frequency/frequency-modulated echolocation sound. There was a marked decline in the value of the relative frequency difference limens (Weber ratio) over a fairly narrow range of frequencies above the constant frequency and a sharp increase in threshold above this range. The relative thresholds for frequency discrimination were small and uniform over the frequency range of the frequency-modulated sweep and increased for frequencies below the frequency-modulated sweep. Thus, the most accurate frequency-discrimination abilities occur over a narrow frequency range around the frequency of the constant-frequency component of returning echoes. Frequency discrimination over the range of frequencies of the frequency-modulated component is relatively good. PMID:10573865

  5. Electromagnetic radiation of variable frequency

    E-print Network

    Kisiel, Zbigniew

    Electromagnetic radiation of variable frequency Wojciech Tadeusz Chyla, PhD Self-review of research ....................................................................................................................................... 5 PART II DISCUSSION OF THE SINGLE-TOPIC CYCLE OF PUBLICATIONS Electromagnetic radiation of variable activities #12;Wojciech Tadeusz Chyla, PhD ­ Self-review of research activities 2/50 Electromagnetic

  6. Frequency agile optical parametric oscillator

    DOEpatents

    Velsko, S.P.

    1998-11-24

    The frequency agile OPO device converts a fixed wavelength pump laser beam to arbitrary wavelengths within a specified range with pulse to pulse agility, at a rate limited only by the repetition rate of the pump laser. Uses of this invention include Laser radar, LIDAR, active remote sensing of effluents/pollutants, environmental monitoring, antisensor lasers, and spectroscopy. 14 figs.

  7. Frequency agile optical parametric oscillator

    DOEpatents

    Velsko, Stephan P. (Livermore, CA)

    1998-01-01

    The frequency agile OPO device converts a fixed wavelength pump laser beam to arbitrary wavelengths within a specified range with pulse to pulse agility, at a rate limited only by the repetition rate of the pump laser. Uses of this invention include Laser radar, LIDAR, active remote sensing of effluents/pollutants, environmental monitoring, antisensor lasers, and spectroscopy.

  8. Frequency Allocation; The Radio Spectrum.

    ERIC Educational Resources Information Center

    Federal Communications Commission, Washington, DC.

    The Federal Communications Commission (FCC) assigns segments of the radio spectrum to categories of users, and specific frequencies within each segment to individual users. Since demand for channel space exceeds supply, the process is complex. The radio spectrum can be compared to a long ruler: the portion from 10-540 kiloHertz has been set aside…

  9. Ionospheric very low frequency transmitter

    NASA Astrophysics Data System (ADS)

    Kuo, Spencer P.

    2015-02-01

    The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HF heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach generates VLF radiations over a larger frequency band than by the modulated electrojet.

  10. 47 CFR 95.1401 - Frequency.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES Personal Locator Beacons (PLB). § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  11. 47 CFR 95.1401 - Frequency.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... SERVICES Personal Locator Beacons (PLB) § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  12. 47 CFR 95.1401 - Frequency.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SERVICES Personal Locator Beacons (PLB) § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  13. 47 CFR 95.1401 - Frequency.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SERVICES Personal Locator Beacons (PLB). § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  14. 47 CFR 95.1401 - Frequency.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES Personal Locator Beacons (PLB) § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  15. NRL Low-Frequency Antenna Development

    E-print Network

    Ellingson, Steven W.

    NRL Low-Frequency Antenna Development Brian Hicks W. Erickson, K. Stewart #12;NRL Low Frequency Antenna Development Our goal has been to research and develop wide- bandwidth low-frequency antennas.g. Galactic drift scans, solar bursts, and other strong sources) #12;NRL Low Frequency Antenna Development

  16. 47 CFR 87.349 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Aeronautical Utility Mobile Stations § 87.349 Frequencies. (a) The frequency assigned to an aeronautical... communications with vehicles. In addition to the ground control frequency, an aeronautical utility station at an... band 121.600-121.925 MHz. (b) The frequency assigned to the unicom is available to aeronautical...

  17. 47 CFR 87.349 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Aeronautical Utility Mobile Stations § 87.349 Frequencies. (a) The frequency assigned to an aeronautical... communications with vehicles. In addition to the ground control frequency, an aeronautical utility station at an... band 121.600-121.925 MHz. (b) The frequency assigned to the unicom is available to aeronautical...

  18. 47 CFR 87.349 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Aeronautical Utility Mobile Stations § 87.349 Frequencies. (a) The frequency assigned to an aeronautical... communications with vehicles. In addition to the ground control frequency, an aeronautical utility station at an... band 121.600-121.925 MHz. (b) The frequency assigned to the unicom is available to aeronautical...

  19. 47 CFR 87.349 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Aeronautical Utility Mobile Stations § 87.349 Frequencies. (a) The frequency assigned to an aeronautical... communications with vehicles. In addition to the ground control frequency, an aeronautical utility station at an... band 121.600-121.925 MHz. (b) The frequency assigned to the unicom is available to aeronautical...

  20. 47 CFR 87.349 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Aeronautical Utility Mobile Stations § 87.349 Frequencies. (a) The frequency assigned to an aeronautical... communications with vehicles. In addition to the ground control frequency, an aeronautical utility station at an... band 121.600-121.925 MHz. (b) The frequency assigned to the unicom is available to aeronautical...

  1. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... frequencies 121.950, 123.300 and 123.500 MHz are available for assignment to aviation support stations used... their eligibility although the Commission reserves the right to specify the frequency of assignment... frequency 122.850 MHz are available for assignment to aviation support stations. These frequencies may...

  2. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.475 Section 87.475 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Stations in the Radiodetermination Service § 87.475 Frequencies. (a) Frequency coordination. The Commission will assign frequencies...

  3. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... frequencies 121.950, 123.300 and 123.500 MHz are available for assignment to aviation support stations used... their eligibility although the Commission reserves the right to specify the frequency of assignment... frequency 122.850 MHz are available for assignment to aviation support stations. These frequencies may...

  4. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... frequencies 121.950, 123.300 and 123.500 MHz are available for assignment to aviation support stations used... their eligibility although the Commission reserves the right to specify the frequency of assignment... frequency 122.850 MHz are available for assignment to aviation support stations. These frequencies may...

  5. Sound Transmission Signal degradation in frequency

    E-print Network

    Wilkinson, Gerald S.

    Sound Transmission · Signal degradation in frequency and time domains ­ Attenuation, absorption-frequency perception · All animals have a threshold frequency at which sounds are perceived either in the time can result from attenuation, loss of pattern and masking by noise Time domain Frequency domain

  6. High frequency power distribution system

    NASA Technical Reports Server (NTRS)

    Patel, Mikund R.

    1986-01-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  7. Natural frequency of regular basins

    NASA Astrophysics Data System (ADS)

    Tjandra, Sugih S.; Pudjaprasetya, S. R.

    2014-03-01

    Similar to the vibration of a guitar string or an elastic membrane, water waves in an enclosed basin undergo standing oscillatory waves, also known as seiches. The resonant (eigen) periods of seiches are determined by water depth and geometry of the basin. For regular basins, explicit formulas are available. Resonance occurs when the dominant frequency of external force matches the eigen frequency of the basin. In this paper, we implement the conservative finite volume scheme to 2D shallow water equation to simulate resonance in closed basins. Further, we would like to use this scheme and utilizing energy spectra of the recorded signal to extract resonant periods of arbitrary basins. But here we first test the procedure for getting resonant periods of a square closed basin. The numerical resonant periods that we obtain are comparable with those from analytical formulas.

  8. Frequency-Selective Microwave Reflectors

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao

    1994-01-01

    Lightweight dichroic reflector panels developed for use in multiplexing electromagnetic waves at three or four microwave frequencies. Basic requirement: panels be highly reflective in X and Ka bands and highly transmissive in Ku and S bands. Intended application in subreflector of main paraboloidal reflector to enable simultaneous operation in both prime-focus configuration in Ku and S bands and Cassegrain configuration in X and Ka bands.

  9. HELIOS dual swept frequency radiometer

    NASA Technical Reports Server (NTRS)

    White, J. R.

    1975-01-01

    The HELIOS dual swept frequency radiometer, used in conjunction with a dipole antenna, was designed to measure electromagnetic radiation in space. An engineering prototype was fabricated and tested on the HELIOS spacecraft. Two prototypes and two flight units were fabricated and three of the four units were integrated into the HELIOS spacecraft. Two sets of ground support equipment were provided for checkout of the radiometer.

  10. Variable frequency microwave furnace system

    DOEpatents

    Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

    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).

  11. 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.

  12. Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

    E-print Network

    Bruno Chanteau; Olivier Lopez; Wei Zhang; Giorgio Santarelli; Yann Le Coq; Frédéric Auguste; Benoît Darquié; Christian Chardonnet; Anne Amy-Klein

    2012-10-13

    We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules.

  13. Temperature and baric dependence of nuclear quadruple resonance spectra in indium and gallium monoselenides

    NASA Astrophysics Data System (ADS)

    Khandozhko, Victor; Raranskii, Nikolai; Balazjuk, Vitaly; Samila, Andriy; Kovalyuk, Zahar

    2013-12-01

    Pulsed radiospectroscopy method has been used to study nuclear quadruple resonance (NQR) spectra of 69Ga and 115In isotopes in the layered semiconductors GaSe and InSe. It has been found that in GaSe and InSe there is a considerable temperature dependence of NQR frequency which in the temperature range of 250 to 390 K is practically linear with conversion slope 1.54 kHz/degree for 69Ga and 2.35 kHz/degree for 115In. In the same crystals the effect of uniaxial pressure on NQR spectra applied along the optical axis ? up to the values of 500 kg/?m2 has been studied. A strong attenuation of NQR spectra intensity with increase in pressure on layered crystal package has been established. The unvaried multiplicity of resonance spectra indicates the absence of structural transformations in these layered crystals over the investigated range of temperatures and pressures.

  14. A tunable dual frequency dye laser - dual frequency oscillator design

    NASA Technical Reports Server (NTRS)

    Abury, Y.

    1983-01-01

    The pulsed dye laser offers a tunable oscillator, followed by three amplifiers. It is pumped by a dual frequency Nd:YAG laser. Tuning and spectral width are controlled by a holographic network connected to a high power telescope. The modified two wavelength dye laser allows for absorption lidar techniques for remote sensing of the atmosphere. Line switching is achieved by electrooptical commutation. A feasibility experiment was performed with the original oscillator. A model was then built, and tested with different dyes. After a few modifications were made to improve the conversion efficiency, this oscillator was inserted in the laser to check whether the amplifier stages were correctly adjusted.

  15. Multi-frequency communication system and method

    DOEpatents

    Carrender, Curtis Lee; Gilbert, Ronald W.

    2004-06-01

    A multi-frequency RFID remote communication system is provided that includes a plurality of RFID tags configured to receive a first signal and to return a second signal, the second signal having a first frequency component and a second frequency component, the second frequency component including data unique to each remote RFID tag. The system further includes a reader configured to transmit an interrogation signal and to receive remote signals from the tags. A first signal processor, preferably a mixer, removes an intermediate frequency component from the received signal, and a second processor, preferably a second mixer, analyzes the IF frequency component to output data that is unique to each remote tag.

  16. Highly Linear, Wide-Range, Swept Frequency Generation at Microwave and Optical Frequencies

    NASA Technical Reports Server (NTRS)

    Lutes, George; Yao, X. Steve

    1996-01-01

    Teh resolution of synthetic aperture radar (SAR) is limited by the frequency range and linearity of the transmitted swept frequency signal. Substantial improvement of the range and linearity of today's all electronic swept frequency generators has proven difficult.

  17. 47 CFR 5.85 - Frequencies and policy governing frequency assignment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...experimental stations may not use any frequency or frequency band exclusively allocated to the passive services (including the radio astronomy service). Stations authorized under subparts E and F are subject to additional restrictions. (b) Frequency or...

  18. 47 CFR 5.85 - Frequencies and policy governing frequency assignment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...experimental stations may not use any frequency or frequency band exclusively allocated to the passive services (including the radio astronomy service). Stations authorized under subparts E and F are subject to additional restrictions. (b) Frequency or...

  19. 47 CFR 87.287 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Aeronautical Fixed Stations, and Aircraft Data Link Land Test Stations Aircraft Data Link Land Test Stations § 87.287 Frequencies. (a) The frequencies assignable to aircraft data link land test stations are 131.450 MHz,...

  20. Very High Frequency Silicon Nanowire Electromechanical Resonators

    E-print Network

    Roukes, Michael L.

    detec- tion,3 quantum electromechanics,4 electromechanical signal generation and processing,5 and highVery High Frequency Silicon Nanowire Electromechanical Resonators X. L. Feng, Rongrui He, Peidong in resonant sensing, quantum electromechanical systems, and high frequency signal processing

  1. 47 CFR 87.279 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Fixed Stations § 87.279 Frequencies. (a... use of the aeronautical enroute frequencies specified in § 87.263(c). kHz 2648.0 5310.0 4645.0...

  2. 47 CFR 87.279 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Fixed Stations § 87.279 Frequencies. (a... use of the aeronautical enroute frequencies specified in § 87.263(c). kHz 2648.0 5310.0 4645.0...

  3. 47 CFR 87.279 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Fixed Stations § 87.279 Frequencies. (a... use of the aeronautical enroute frequencies specified in § 87.263(c). kHz 2648.0 5310.0 4645.0...

  4. 47 CFR 87.279 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Fixed Stations § 87.279 Frequencies. (a... use of the aeronautical enroute frequencies specified in § 87.263(c). kHz 2648.0 5310.0 4645.0...

  5. 47 CFR 24.229 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...PERSONAL COMMUNICATIONS SERVICES Broadband PCS § 24.229 Frequencies. The frequencies available in the Broadband PCS service are listed in this section...1910-1915 MHz block shall be used for mobile/portable station...

  6. Frequency selective surfaces for Terahertz applications 

    E-print Network

    Sanz Fernandez, Juan Jose; Fernandez, Juan Jose Sanz

    2012-11-29

    This thesis presents both theoretical and experimental investigations of the performance and capabilities of frequency selective surfaces (FSS) applied at THz frequencies. The aim is to explore and extend the use of FSS, ...

  7. Frequency Synthesis in Wireless and Wireline Systems 

    E-print Network

    Turker, Didem 1981-

    2010-12-06

    First, a frequency synthesizer for IEEE 802.15.4 / ZigBee transceiver applications that employs dynamic True Single Phase Clocking (TSPC) circuits in its frequency dividers is presented and through the analysis and measurement results...

  8. Low-frequency data analysis and expansion

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Hua; Zhang, Bin-Bin; Zhang, Zai-Jin; Liang, Hong-Xian; Ge, Da-Ming

    2015-06-01

    The use of low-frequency seismic data improves the seismic resolution, and the imaging and inversion quality. Furthermore, low-frequency data are applied in hydrocarbon exploration; thus, we need to better use low-frequency data. In seismic wavelets, the loss of low-frequency data decreases the main lobe amplitude and increases the first side lobe amplitude and results in the periodic shocking attenuation of the secondary side lobe. The loss of low frequencies likely produces pseudo-events and the false appearance of higher resolution. We use models to examine the removal of low-frequency data in seismic data processing. The results suggest that the removal of low frequencies create distortions, especially for steep structures and thin layers. We also perform low-frequency expansion using compressed sensing and sparse constraints and develop the corresponding module. Finally, we apply the proposed method to real common image point gathers with good results.

  9. Frequency domain design of interval controller 

    E-print Network

    Park, Wunyong

    1993-01-01

    significant role in the analysis and design of interval systems. Its external properties are also discussed. The image set approach & frequency domain criteria can be used to calculate the IP stability margin. The frequency domain criteria are used...

  10. 47 CFR 87.41 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with the center of an authorized bandwidth of emission must be specified as the assigned frequency. For.... Frequencies are available for assignment to stations on a shared basis only and will not be assigned for...

  11. 47 CFR 87.41 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with the center of an authorized bandwidth of emission must be specified as the assigned frequency. For.... Frequencies are available for assignment to stations on a shared basis only and will not be assigned for...

  12. 47 CFR 87.41 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with the center of an authorized bandwidth of emission must be specified as the assigned frequency. For.... Frequencies are available for assignment to stations on a shared basis only and will not be assigned for...

  13. 47 CFR 87.41 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with the center of an authorized bandwidth of emission must be specified as the assigned frequency. For.... Frequencies are available for assignment to stations on a shared basis only and will not be assigned for...

  14. 47 CFR 87.41 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with the center of an authorized bandwidth of emission must be specified as the assigned frequency. For.... Frequencies are available for assignment to stations on a shared basis only and will not be assigned for...

  15. Relativistic Frequency Synthesis of Light Fields

    E-print Network

    C. Rödel; E. Eckner; J. Bierbach; M. Yeung; B. Dromey; T. Hahn; S. Fuchs; A. Galestian Pour; M. Wünsche; S. Kuschel; D. Hemmers; O. Jäckel; G. Pretzler; M. Zepf; G. G. Paulus

    2013-10-29

    Waveform shaping and frequency synthesis based on waveform modulation is ubiquitous in electronics, telecommunication technology, and optics. For optical waveforms, the carrier frequency is on the order of several hundred THz, while the modulation frequencies used in conventional devices like electro- or acousto-optical modulators are orders of magnitude lower. As a consequence, any new frequencies are typically very close to the fundamental. The synthesis of new frequencies in the extreme ultraviolet (XUV), e.g. by using relativistic oscillating mirrors, requires modulation frequencies in the optical regime or even in the extreme ultraviolet. The latter has not been proven possible to date. Here we demonstrate that individual strong harmonics can indeed be generated by reflecting light off a plasma surface that oscillates at XUV frequencies. The strong harmonics are explained by nonlinear frequency mixing of near-infrared light and a laser-driven plasma oscillation in the extreme ultra-violet mediated by a relativistic non-linearity.

  16. Substructure coupling in the frequency domain

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Frequency domain analysis was found to be a suitable method for determining the transient response of systems subjected to a wide variety of loads. However, since a large number of calculations are performed within the discrete frequency loop, the method loses it computational efficiency if the loads must be represented by a large number of discrete frequencies. It was also discovered that substructure coupling in the frequency domain work particularly well for analyzing structural system with a small number of interface and loaded degrees of freedom. It was discovered that substructure coupling in the frequency domain can lead to an efficient method of obtaining natural frequencies of undamped structures. It was also found that the damped natural frequencies of a system may be determined using frequency domain techniques.

  17. Radio frequency power load and associated method

    NASA Technical Reports Server (NTRS)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

    2010-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus includes a container and a fluid having an ion source therein, the fluid being contained in the container. Two conductors are immersed in the fluid. A radio frequency transmission system includes a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus includes a fluid having an ion source therein, and two conductors immersed in the fluid. A method of dissipating power generated by a radio frequency transmission system includes the steps of: immersing two conductors of a radio frequency power load apparatus in a fluid having an ion source therein; and connecting the apparatus to an amplifier of the transmission system.

  18. Environmental Tests Of Cesium Frequency Standards

    NASA Technical Reports Server (NTRS)

    Sydnor, Richard L.; Tucker, Thomas K.; Greenhall, Charles A.; Diener, William A.; Maleki, Lutfollah

    1992-01-01

    Report describes environmental tests of cesium-beam frequency standards of United States Naval Observatory. Purpose of tests to determine effects of atmospheric temperature, relative humidity, and pressure on frequencies.

  19. Stabilization of a Kerr frequency comb oscillator.

    PubMed

    Savchenkov, A A; Eliyahu, D; Liang, W; Ilchenko, V S; Byrd, J; Matsko, A B; Seidel, D; Maleki, L

    2013-08-01

    We study stability and spectral purity of a microresonator-based Kerr frequency comb oscillator experimentally and observe a correlation between the frequency of the continuous wave laser pumping the nonlinear resonator and the repetition frequency of the comb. This correlation is used in a proof-of-principle demonstration of a Kerr frequency comb stabilized with an optical transition of 87Rb. PMID:23903097

  20. Atomic quantum memory for multimode frequency combs

    E-print Network

    Z. Zheng; O. Mishina; N. Treps; C. Fabre

    2015-04-06

    We propose a Raman quantum memory scheme that uses several atomic ensembles to store and retrieve the multimode highly entangled state of an optical quantum frequency comb, such as the one produced by parametric down-conversion of a pump frequency comb. We analyse the efficiency and the fidelity of such a quantum memory. Results show that our proposal may be helpful to multimode information processing using the different frequency bands of an optical frequency comb.

  1. Low frequency ac waveform generator

    DOEpatents

    Bilharz, O.W.

    1983-11-22

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stablization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  2. Low frequency AC waveform generator

    DOEpatents

    Bilharz, Oscar W. (Scotia, NY)

    1986-01-01

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stabilization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform itself. The cosine is synthesized by squaring the triangular waveform, raising the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  3. Landau damping with high frequency impedance

    SciTech Connect

    Blaskiewicz,M.

    2009-05-04

    Coupled bunch longitudinal stability in the presence of high frequency impedances is considered. A frequency domain technique is developed and compared with simulations. The frequency domain technique allows for absolute stability tests and is applied to the problem of longitudinal stability in RHIC with the new 56 MHz RF system.

  4. 47 CFR 87.217 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies. 87.217 Section 87.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Advisory Stations (Unicoms) § 87.217 Frequencies. (a) Only one unicom frequency will be...

  5. 47 CFR 87.351 - Frequency changes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequency changes. 87.351 Section 87.351 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Utility Mobile Stations § 87.351 Frequency changes. When the aeronautical utility frequency...

  6. 47 CFR 87.217 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.217 Section 87.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Advisory Stations (Unicoms) § 87.217 Frequencies. (a) Only one unicom frequency will be...

  7. 47 CFR 87.351 - Frequency changes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequency changes. 87.351 Section 87.351 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Utility Mobile Stations § 87.351 Frequency changes. When the aeronautical utility frequency...

  8. 47 CFR 87.217 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies. 87.217 Section 87.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Advisory Stations (Unicoms) § 87.217 Frequencies. (a) Only one unicom frequency will be...

  9. 47 CFR 87.217 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies. 87.217 Section 87.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Advisory Stations (Unicoms) § 87.217 Frequencies. (a) Only one unicom frequency will be...

  10. 47 CFR 87.351 - Frequency changes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequency changes. 87.351 Section 87.351 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Utility Mobile Stations § 87.351 Frequency changes. When the aeronautical utility frequency...

  11. 47 CFR 87.351 - Frequency changes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequency changes. 87.351 Section 87.351 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Utility Mobile Stations § 87.351 Frequency changes. When the aeronautical utility frequency...

  12. 47 CFR 87.351 - Frequency changes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequency changes. 87.351 Section 87.351 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Utility Mobile Stations § 87.351 Frequency changes. When the aeronautical utility frequency...

  13. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Aeronautical Enroute Stations, Aeronautical Fixed Stations, and Aircraft Data Link Land Test Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a) Domestic VHF service. (1) Frequencies in the 128.8125... frequency 136.750 MHz is available only to aeronautical enroute stations located at least 288...

  14. 47 CFR 87.217 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 87.217 Section 87.217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Advisory Stations (Unicoms) § 87.217 Frequencies. (a) Only one unicom frequency will be...

  15. High frequency-heated air turbojet

    NASA Technical Reports Server (NTRS)

    Miron, J. H. D.

    1986-01-01

    A description is given of a method to heat air coming from a turbojet compressor to a temperature necessary to produce required expansion without requiring fuel. This is done by high frequency heating, which heats the walls corresponding to the combustion chamber in existing jets, by mounting high frequency coils in them. The current transformer and high frequency generator to be used are discussed.

  16. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequency assignments. 101.147 Section 101.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.147 Frequency assignments. (a) Frequencies in the following bands are available for assignment...

  17. 47 CFR 87.187 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.187 Section 87.187 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations § 87.187 Frequencies. (a) Frequencies used for air-ground Communications are listed in subpart E. Aircraft stations may...

  18. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.323 Section 87.323 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aviation Support Stations § 87.323 Frequencies. (a) 121.500 MHz: Emergency and distress only. (b) The frequencies 121.950, 123.300 and 123.500...

  19. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 87.323 Section 87.323 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aviation Support Stations § 87.323 Frequencies. (a) 121.500 MHz: Emergency and distress only. (b) The frequencies 121.950, 123.300 and 123.500...

  20. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 101.803 Section 101.803 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.803 Frequencies. (a) Frequencies in the following bands are available for assignment...

  1. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 101.803 Section 101.803 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.803 Frequencies. (a) Frequencies in the following bands are available for assignment...

  2. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequency assignments. 101.147 Section 101.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.147 Frequency assignments. (a) Frequencies in the following bands are available for assignment...

  3. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... service. (7) This frequency band is shared with space stations (space to earth) in the earth exploration... GHz band. (4) This frequency band is shared with stations in the earth-exploration satellite service... other parts of the Commission's rules. (3) This frequency band is shared with space stations (space...

  4. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies. 101.803 Section 101.803 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.803 Frequencies. (a) Frequencies in the following bands are available for assignment...

  5. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... service. (7) This frequency band is shared with space stations (space to earth) in the earth exploration... GHz band. (4) This frequency band is shared with stations in the earth-exploration satellite service... other parts of the Commission's rules. (3) This frequency band is shared with space stations (space...

  6. 47 CFR 101.107 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequency tolerance. 101.107 Section 101.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.107 Frequency tolerance. (a) The carrier frequency of each...

  7. 47 CFR 101.505 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies. 101.505 Section 101.505 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.505 Frequencies. Frequencies, and...

  8. 47 CFR 101.1005 - Frequencies available.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies available. 101.1005 Section 101.1005 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Multipoint Distribution Service § 101.1005 Frequencies available. (a) The following frequencies are available...

  9. 47 CFR 101.505 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 101.505 Section 101.505 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.505 Frequencies. Frequencies, and the conditions on which they are...

  10. 47 CFR 87.187 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... radionavigation land station scope of service. (b) 410 kHz is the international direction-finding frequency for... over the high seas. (d) 500 kHz an international calling and distress frequency for aircraft on flights... h.45 Coordinated Universal Time (u.t.c.). (e) The frequency 2182 khz is an international...

  11. 47 CFR 87.187 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... radionavigation land station scope of service. (b) 410 kHz is the international direction-finding frequency for... over the high seas. (d) 500 kHz an international calling and distress frequency for aircraft on flights... h.45 Coordinated Universal Time (u.t.c.). (e) The frequency 2182 khz is an international...

  12. 47 CFR 87.187 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... radionavigation land station scope of service. (b) 410 kHz is the international direction-finding frequency for... over the high seas. (d) 500 kHz an international calling and distress frequency for aircraft on flights... h.45 Coordinated Universal Time (u.t.c.). (e) The frequency 2182 khz is an international...

  13. 47 CFR 87.187 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... radionavigation land station scope of service. (b) 410 kHz is the international direction-finding frequency for... over the high seas. (d) 500 kHz an international calling and distress frequency for aircraft on flights... h.45 Coordinated Universal Time (u.t.c.). (e) The frequency 2182 khz is an international...

  14. 47 CFR 27.5 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Frequencies. 27.5 Section 27.5 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES General Information § 27.5 Frequencies. (a) 2305-2320 MHz and 2345-2360 MHz bands. The following frequencies are available for...

  15. METHODS OF RADIO-FREQUENCY CURRENT DRIVE

    E-print Network

    -670 Radio-frequency waves can penetrate thermonuclear plasmas, depositing momentum and energy with great. INTRODUCTION Using radio-frequency (rf) waves to drive the toroidal current in tokamak reactors is attractiveMETHODS OF RADIO-FREQUENCY CURRENT DRIVE N. J. FISCH* Princeton Plasma Physics Laboratory

  16. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...in this part, the frequency pairs 12.220/12.460...one frequency of a frequency pair for a one-way...58 GHz for multichannel video programming distribution are governed...7-17.74 GHz sub-band to pair with other channels in...

  17. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...in this part, the frequency pairs 12.220/12.460...one frequency of a frequency pair for a one-way...58 GHz for multichannel video programming distribution are governed...7-17.74 GHz sub-band to pair with other channels in...

  18. Judging the Frequency of English Words

    ERIC Educational Resources Information Center

    Alderson, J. Charles

    2007-01-01

    Given the lack of empirical corpus-based frequency counts in many languages, it would be useful and of theoretical interest if judgements of relative frequency of words in a language by proficient speakers of that language could substitute objective frequency counts for the purposes of devising language teaching materials, tests, and research…

  19. 47 CFR 5.403 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...including those above 38.6 GHz, except for frequency bands exclusively allocated to the passive services (including the radio astronomy service). In addition, licensees may not use any frequency or frequency band below 38.6 GHz that is listed in §...

  20. 47 CFR 5.403 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...including those above 38.6 GHz, except for frequency bands exclusively allocated to the passive services (including the radio astronomy service). In addition, licensees may not use any frequency or frequency band below 38.6 GHz that is listed in §...

  1. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... following conditions apply: (i) The maximum power authorized on the frequencies 108.150 and 334.550 MHz is 1 milliwatt. The maximum power authorized on all other frequencies is one watt. (ii) The pulse repetition rate... to change frequency, power, location or emission. Each application must include the FAA...

  2. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following conditions apply: (i) The maximum power authorized on the frequencies 108.150 and 334.550 MHz is 1 milliwatt. The maximum power authorized on all other frequencies is one watt. (ii) The pulse repetition rate... to change frequency, power, location or emission. Each application must include the FAA...

  3. 47 CFR 87.475 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... following conditions apply: (i) The maximum power authorized on the frequencies 108.150 and 334.550 MHz is 1 milliwatt. The maximum power authorized on all other frequencies is one watt. (ii) The pulse repetition rate... to change frequency, power, location or emission. Each application must include the FAA...

  4. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except... allocated for use by ISM equipment: ISM frequency Tolerance 6.78 MHz ±15.0 kHz 13.56 MHz ±7.0 kHz 27.12...

  5. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except... allocated for use by ISM equipment: ISM frequency Tolerance 6.78 MHz ±15.0 kHz 13.56 MHz ±7.0 kHz 27.12...

  6. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except... allocated for use by ISM equipment: ISM frequency Tolerance 6.78 MHz ±15.0 kHz 13.56 MHz ±7.0 kHz 27.12...

  7. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Operating frequencies. 18.301 Section 18.301 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in §...

  8. 47 CFR 18.301 - Operating frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Operating frequencies. 18.301 Section 18.301 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.301 Operating frequencies. ISM equipment may be operated on any frequency above 9 kHz except as indicated in §...

  9. Frequency Comb Generation in Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Erickson, R. P.; Vissers, M. R.; Sandberg, M.; Jefferts, S. R.; Pappas, D. P.

    2014-10-01

    We have generated frequency combs spanning 0.5 to 20 GHz in superconducting ? /2 resonators at T =3 K . Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical temperature. The combs nucleate as sidebands around multiples of the pump frequency. Selection rules for the allowed frequency emission are calculated using perturbation theory, and the measured spectrum is shown to agree with the theory. Sideband spacing is measured to be accurate to 1 part in 1 08. The sidebands coalesce into a continuous comb structure observed to cover at least several frequency octaves.

  10. Multiple frequency method for operating electrochemical sensors

    DOEpatents

    Martin, Louis P. (San Ramon, CA)

    2012-05-15

    A multiple frequency method for the operation of a sensor to measure a parameter of interest using calibration information including the steps of exciting the sensor at a first frequency providing a first sensor response, exciting the sensor at a second frequency providing a second sensor response, using the second sensor response at the second frequency and the calibration information to produce a calculated concentration of the interfering parameters, using the first sensor response at the first frequency, the calculated concentration of the interfering parameters, and the calibration information to measure the parameter of interest.

  11. Magnetic Earth Ionosphere Resonant Frequencies

    NASA Technical Reports Server (NTRS)

    Spaniol, Craig

    1994-01-01

    The Community College Division is pleased to report progress of NASA funded research at West Virginia State College. During this reporting period, the project research group has continued with activities to develop instrumentation capability designed to monitor resonant cavity frequencies in the atmospheric region between the Earth's surface and the ionosphere. In addition, the project's principal investigator, Dr. Craig Spaniol, and NASA technical officer, Dr. John Sutton, have written and published technical papers intended to expand the scientific and technical framework needed for project research. This research continues to provide an excellent example of government and education working together to provide significant research in the college environment. This cooperative effort has provided many students with technical project work which compliments their education.

  12. Dermatomycosis Frequency and Localization Sites

    PubMed Central

    Koçinaj, Allma Ferizi; Kotori, Merita Grajqevci; Koraqi, Andi; Fida, Monika

    2015-01-01

    Introduction: Since the prevalence of skin mycotic infections is changing and is area depended we aimed to analyze the frequency of the skin myocotic infections and the appearance sites. Material and Methods: There were involved 560 patients referred to the Dermatology Clinic of University Clinical Center of Kosova during a period of one year. Results: The mean age of our study group was around thirties with a predominance of female and rural patients. Although most of cases presented with single site disease localization, we observed the increase in number of cases with more than one site localization with age. Conclusion: The increased prevalence skin mycotic infections, as well as more than one place of localization deserve a multidimensional approach. PMID:25870481

  13. Frequency domain optical parametric amplification

    PubMed Central

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-01-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43?mJ two-cycle pulses at 1.8??m wavelength. PMID:24805968

  14. A radio frequency coaxial feedthrough

    DOEpatents

    Owens, T.L.

    1987-12-07

    An improved radio frequency coaxial transmission line vacuum feedthrough is provided based on the use of a half-wavelength annular dielectric pressure barrier disk, or multiple disks comprising an effective half wavelength structure to eliminate reflection from the barrier surfaces. Gas-tight seals are formed about the outer and inner diameter surfaces of the barrier disk using a sealing technique which generates radial forces sufficient to form seals by forcing the conductor walls against the surfaces of the barrier disks in a manner which does not deform the radii of the inner and outer conductors, thereby preventing enhancement of the electric field at the barrier faces which limits the voltage and power handling capabilities of a feedthrough.

  15. Frequency stabilization of algaas lasers

    SciTech Connect

    Ohtsu, M.; Tsuchida, H.; Tako, T.

    1982-01-01

    Performances of semiconductor lasers have been remarkably improved by the demand of the optical communications industry. Recently, a single longitudinal mode, CW oscillation at room temperature has been realized. The price of each laser has been reduced as low as $250. These lasers are mostly oscillated in the near-infrared, and the coherent lights of 0.83 micrometers and 1.3-1.6 micrometers in wavelengths are obtained by AlGaAs lasers and InGaAsP lasers, respectively. Since few number of other kind of lasers oscillates in these wavelength regions, these semiconductor lasers could be conveniently used not only in optical communications but in many fields of application, e.g., laser spectroscopy, optical pumping, frequency and length standards, laser radar, air-borne gyroscope, etc.

  16. Magnetic nanocomposites at microwave frequencies

    E-print Network

    Timonen, J V I; Ikkala, O; Oksanen, M; Seppala, E; Chalapat, K; Li, J; Paraoanu, G S; 10.1007/978-3-642-12070-1\\_11

    2011-01-01

    Most conventional magnetic materials used in the electronic devices are ferrites, which are composed of micrometer-size grains. But ferrites have small saturation magnetization, therefore the performance at GHz frequencies is rather poor. That is why functionalized nanocomposites comprising magnetic nanoparticles (e.g. Fe, Co) with dimensions ranging from a few nm to 100 nm, and embedded in dielectric matrices (e.g. silicon oxide, aluminium oxide) have a significant potential for the electronics industry. When the size of the nanoparticles is smaller than the critical size for multidomain formation, these nanocomposites can be regarded as an ensemble of particles in single-domain states and the losses (due for example to eddy currents) are expected to be relatively small. Here we review the theory of magnetism in such materials, and we present a novel measurement method used for the characterization of the electromagnetic properties of composites with nanomagnetic insertions. We also present a few experimenta...

  17. Lightweight, high-frequency transformers

    NASA Technical Reports Server (NTRS)

    Schwarze, G. E.

    1983-01-01

    The 25-kVA space transformer was developed under contract by Thermal Technology Laboratory, Buffalo, N. Y. The NASA Lewis transformer technology program attempted to develop the baseline technology. For the 25-kVA transformer the input voltage was chosen as 200 V, the output voltage as 1500 V, the input voltage waveform as square wave, the duty cycle as continuous, the frequency range (within certain constraints) as 10 to 40 kHz, the operating temperatures as 85 deg. and 130 C, the baseplate temperature as 50 C, the equivalent leakage inductance as less than 10 micro-h, the operating environment as space, and the life expectancy as 10 years. Such a transformer can also be used for aircraft, ship and terrestrial applications.

  18. LOFAR- The Low Frequency Array

    NASA Astrophysics Data System (ADS)

    Falcke, H. D. E.

    2006-08-01

    LOFAR is an innovative radio telescope in the frequency range of 10-240 MHz, realized as a phased array. It will become the largest radio telescope in the world in the time frame 2006-2010, located in Northern Europe. LOFAR is being implemented as a Wide Area Sensor Network which connects thousands of cheap sensors spread throughout the country to a central super computer using an ultra-broadband, synchronized data network. As the central processor IBM has provided its Blue Gene/L supercomputer. It will process streaming data with about 0.5 Terabit per second. Many simple radio antennas connected to the network turn it into a huge radio telescope for cosmological studies. In addition, geophones will turn LOFAR into an earthquake monitoring system and infrasound and meteorology sensors will turn LOFAR into a real-time weather monitoring array for agricultural applications. LOFAR is the first radio telescopes that can listen to radio signals from the entire sky overhead, on all time scales, at a large range of frequencies, and even look back in time for a couple of seconds. The main strength of LOFAR are surveys. One goal is to detect the first generation of black holes and galaxies in the universe during the epoch of reionization and study hydrogen formed after the big bang. LOFAR is also an ideal system to discover transient and sporadic radio signals. Likely transient sources to be discovered with LOFAR are bursting stars and Jupiter-like planets, gamma-ray bursts, radio outbursts from black holes, but also lightning on Earth and even radio flashes from ultra-high energy cosmic particles hitting the Earth atmosphere. Some LOFAR prototypes have recently been built. They have produced the first instantaneous all-sky maps and discovered the radio emission from cosmic particle air showers.

  19. Coping with Radio Frequency Interference

    NASA Astrophysics Data System (ADS)

    Lewis, B. M.

    2009-01-01

    The radio spectrum is a finite resource, on which humanity makes many demands. And pressure on it is ever increasing with the development of new technology and ideas for radio services. After all, we all benefit from wifi and cell phones. Radio astronomers have a small percentage of the spectrum allocated to them at octave intervals in the metre-centimetre bands, and at important frequencies, such as that of the 21cm line of HI. Signals from other services, as well as from our own poorly-engineered equipment, sometimes contaminate our bands: these signals constitute RFI. These may totally obliterate the astronomical signal, or, in the case of CLOUDSAT, may be capable of completely destroying a receiver, which introduces us to the new possibility of 'destructive interference'. A geo-stationary satellite can block access to a piece of sky from one site. Good equipment design eliminates self-inflicted interference, while physical separation often provides adequate practical mitigation at many frequencies. However, new observatories end up being located in the West Australian desert or Antarctica. In future they may be on the back side of the Moon. But there is no Earth-bound protection via physical separation against satellite signals. Some mitigation can be achieved by frequent data dumps and the excision of RFI, or by real-time detection and blanking of the receiver, or by more sophisticated algoriths. Astronomers of necessity aim to achieve mitigation via coordination, at the local level, and by participating in spectrum management at the national and international levels. This involves them spending a lot of time in Geneva at the International Telegraphic Union protecting their access to spectrum, and access to clean spectrum from the L3 point and the far side of the Moon.

  20. Radio Frequency Power Load and Associated Method

    NASA Technical Reports Server (NTRS)

    Srinivasan, V. Karthik (Inventor); Freestone, Todd M. (Inventor); Sims, William Herbert, III (Inventor)

    2014-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus may include a container with an ionized fluid therein. The apparatus may include one conductor immersed in a fluid and another conductor electrically connected to the container. A radio frequency transmission system may include a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus may include a fluid having an ion source therein, one conductor immersed in a fluid, and another conductor electrically connected to the container. A method of dissipating power generated by a radio frequency transmission system may include constructing a waveguide with ionized fluid in a container and connecting the waveguide to an amplifier of the transmission system.

  1. Optical generation of a precise microwave frequency comb by harmonic frequency locking

    E-print Network

    Chan, Sze-Chun

    comb through the nonlinear dynamics. The laser system is operated in a harmonic frequency- lockedOptical generation of a precise microwave frequency comb by harmonic frequency locking Sze pulsing state, where its power spectrum is a microwave frequency comb that consists of multiples

  2. Frequency discrimination threshold at search call frequencies in the echolocating bat, Eptesicus fuscus.

    PubMed

    von Stebut, B; Schmidt, S

    2001-05-01

    While searching for prey in open spaces, Epteisicus fuscus emits long-duration, downward frequency-modulated calls which cover a frequency band of about 28-22 kHz. In the ascending auditory pathways of E. fuscus, neurons tuned to these search call frequencies are characterised by a remarkably high frequency selectivity and very sensitive absolute thresholds. We investigated whether this narrow tuning is reflected in an exceptional psychoacoustic frequency discrimination ability. The average frequency difference limen of E. fuscus at search call frequencies determined in a two-alternative, forced-choice experiment amounted to about 420 Hz, corresponding to a Weber ratio of 0.017. This value is similar to those found in non-echolocating mammals, and an order of magnitude larger than the frequency difference limens of bats emitting constant-frequency call components. We discuss these differences in frequency difference limen, and relate them to different echolocation strategies. PMID:11467501

  3. Simulation of multi-frequency ECRH

    SciTech Connect

    Rognlien, T.D.

    1981-11-23

    We use a test particle simulation code to investigate electron cyclotron heating in a magnetic mirror well. A comparison is made between heating with one frequency and heating with two closely spaced frequencies. The code follows electron orbits in the presence of one or two monochromatic ECRH waves using guiding center equations and an equation for the electron gyrophase. Coulomb collisions with electrons and ions are simulated as a Monte Carlo scattering process. We find for the parameters of SM-1 that at the fundamental resonance the heating rate, or velocity rf diffusion coefficient, begins to decrease significantly from the quasilinear value for epsilon/sub e/ greater than or equal to 10 keV due to superadiabatic effects. As suggested by Howard et al., using multiple frequencies pushes the superadiabatic boundary to higher energies. For a given energy, the optimum frequency separations for two frequencies are those which cause the axial bounce resonances to interlace; i.e., odd multiples of the bounce frequency, ..omega../sub b/. This interlacing increases the chance of resonance overlap and thus stochasticity. If the frequency difference is equal to an even multiple of ..omega../sub b/, the diffusion coefficient returns to near its one frequency value. More generally, for more than two frequencies one should choose the frequency separation such that the bounce resonances interlace evenly. Detailed calculations are presented for SM-1 parameters.

  4. VCO PLL Frequency Synthesizers for Spacecraft Transponders

    NASA Technical Reports Server (NTRS)

    Smith, Scott; Mysoor, Narayan; Lux, James; Cook, Brian

    2007-01-01

    Two documents discuss a breadboard version of advanced transponders that, when fully developed, would be installed on future spacecraft to fly in deep space. These transponders will be required to be capable of operation on any deepspace- communications uplink frequency channel between 7,145 and 7,235 MHz, and any downlink frequency channel between 8,400 and 8,500 MHz. The document focuses on the design and operation of frequency synthesizers for the receiver and transmitter. Heretofore, frequency synthesizers in deep-space transponders have been based on dielectric resonator oscillators (DROs), which do not have the wide tuning bandwidth necessary to tune over all channels in the uplink or downlink frequency bands. To satisfy the requirement for tuning bandwidth, the present frequency synthesizers are based on voltage-controlled-oscillator (VCO) phase-locked loops (PLLs) implemented by use of monolithic microwave integrated circuits (MMICs) implemented using inGaP heterojunction bipolar transistor (HBT) technology. MMIC VCO PLL frequency synthesizers similar to the present ones have been used in commercial and military applications but, until now, have exhibited too much phase noise for use in deep-space transponders. The present frequency synthesizers contain advanced MMIC VCOs, which use HBT technology and have lower levels of flicker (1/f) phase noise. When these MMIC VCOs are used with high-speed MMIC frequency dividers, it becomes possible to obtain the required combination of frequency agility and low phase noise.

  5. Pulsation frequency distribution in ? Scuti stars

    NASA Astrophysics Data System (ADS)

    Balona, L. A.; Daszy?ska-Daszkiewicz, J.; Pamyatnykh, A. A.

    2015-09-01

    We study the frequency distributions of Delta Scuti (? Scuti) stars observed by the Kepler satellite in short-cadence mode. To minimize errors in the estimated stellar parameters, we divided the instability strip into 10 regions and determined the mean frequency distribution in each region. We confirm that the presence of low frequencies is a property of all ? Sct stars, rendering meaningless the concept of ? Sct/? Dor hybrids. We obtained the true distribution of equatorial rotational velocities in each region and calculated the frequency distributions predicted by pulsation models, taking into account rotational splitting of the frequencies. We confirm that rotation cannot account for the presence of low frequencies. We calculated a large variety of standard pulsation models with different metal and helium abundances, but were unable to obtain unstable low-frequency modes driven by the ? mechanism in any model. We also constructed models with modified opacities in the envelope. Increasing the opacity at a temperature log T = 5.06 by a factor of 2 does lead to instability of low-degree modes at low frequencies, but also decreases the frequency range of ? Sct-type pulsations to some extent. We also re-affirm the fact that less than half of the stars in the ? Sct instability strip have pulsations detectable by Kepler. We also point out the huge variety of frequency patterns in stars with roughly similar parameters, suggesting that non-linearity is an important factor in ? Sct pulsations.

  6. The driving frequency effects on the atmospheric pressure corona jet plasmas from low frequency to radio frequency

    SciTech Connect

    Kim, Dan Bee; Jung, H.; Gweon, B.; Rhee, J. K.; Choe, W.; Moon, S. Y.

    2011-04-15

    Lately, the atmospheric pressure jet type corona plasma, which has been typically driven by dc to low frequency (LF: several tens of kHz), is often generated by using radio frequency of 13.56 MHz. Yet, the relationship between the plasma and its driving frequency has seldom been investigated. Hence, in this study, dependence of the atmospheric pressure corona plasma characteristics on the driving frequency was explored experimentally from LF to rf (5 kHz-13.56 MHz). The plasmas generated by the driving frequency under 2 MHz were cylindrical shape of several tens of millimeters long while the 13.56 MHz plasma is spherical and a few millimeters long. As the driving frequency was increased, the plasma length became shortened. At the lower driving frequencies (below 2 MHz), the plasmas existed as positive streamer and negative glow for each half period of the applied voltage, but the discharge was more continuous in time for the 13.56 MHz plasma. It was inferred from the measured I-V curves that the higher driving frequency induced higher discharge currents, and the gas temperature was increased as the driving frequency was increased.

  7. High-frequency nanophotonic devices

    NASA Astrophysics Data System (ADS)

    Bimberg, D.; Fiol, G.; Meuer, C.; Laemmlin, M.; Kuntz, M.

    2007-02-01

    Recent results on GaAs-based high-speed mode-locked quantum dot (QD) lasers and optical amplifiers with an operation wavelength centered at 1290 nm are reviewed and their complex dependence on device and operating parameters is discussed on the basis of experimental data obtained with integrated fiber-based QD device modules. Hybrid and passive mode-locking of QD lasers with repetition frequencies between 5 and 80 GHz, sub-ps pulse widths, ultra-low timing jitter down to 190 fs, high output peak power beyond 1 W and suppression of Q-switching are reported, showing the large potential of this class of devices for O-band optical fiber applications. Results on cw and dynamical characterization of quantum dot semiconductor optical amplifiers are presented. QD amplifiers exhibit a close-to-ideal noise figure of 4 dB and demonstrate multi-wavelength amplification of three CWDM wavelengths simultaneously. Modelling of QD polarization dependence shows that it should be possible to achieve polarization insensitive SOAs using vertically coupled QD stacks. Amplification of ultra-fast 80 GHz optical combs and bit-error-free data signal amplification at 40 Gb/s with QD SOAs show the potential for their application in future 100 Gb Ethernet networks.

  8. Visible-frequency hyperbolic metasurface

    NASA Astrophysics Data System (ADS)

    High, Alexander A.; Devlin, Robert C.; Dibos, Alan; Polking, Mark; Wild, Dominik S.; Perczel, Janos; de Leon, Nathalie P.; Lukin, Mikhail D.; Park, Hongkun

    2015-06-01

    Metamaterials are artificial optical media composed of sub-wavelength metallic and dielectric building blocks that feature optical phenomena not present in naturally occurring materials. Although they can serve as the basis for unique optical devices that mould the flow of light in unconventional ways, three-dimensional metamaterials suffer from extreme propagation losses. Two-dimensional metamaterials (metasurfaces) such as hyperbolic metasurfaces for propagating surface plasmon polaritons have the potential to alleviate this problem. Because the surface plasmon polaritons are guided at a metal-dielectric interface (rather than passing through metallic components), these hyperbolic metasurfaces have been predicted to suffer much lower propagation loss while still exhibiting optical phenomena akin to those in three-dimensional metamaterials. Moreover, because of their planar nature, these devices enable the construction of integrated metamaterial circuits as well as easy coupling with other optoelectronic elements. Here we report the experimental realization of a visible-frequency hyperbolic metasurface using single-crystal silver nanostructures defined by lithographic and etching techniques. The resulting devices display the characteristic properties of metamaterials, such as negative refraction and diffraction-free propagation, with device performance greatly exceeding those of previous demonstrations. Moreover, hyperbolic metasurfaces exhibit strong, dispersion-dependent spin-orbit coupling, enabling polarization- and wavelength-dependent routeing of surface plasmon polaritons and two-dimensional chiral optical components. These results open the door to realizing integrated optical meta-circuits, with wide-ranging applications in areas from imaging and sensing to quantum optics and quantum information science.

  9. Frequency-offset separated oscillatory fields

    NASA Astrophysics Data System (ADS)

    Vutha, A. C.; Hessels, E. A.

    2015-11-01

    A frequency-offset separated-oscillatory-field technique is presented. The technique is a modification of the Ramsey method of separated oscillatory fields [Phys. Rev. 76, 996 (1949), 10.1103/PhysRev.76.996], in which the frequencies of the two separated oscillatory fields are slightly offset from each other, so that the relative phase of the two fields varies continuously with time. With this technique, the detection signal oscillates in time at the offset frequency, and the resonance frequency is obtained by using a simple straight-line fit of the phase of this signal. The technique has the advantages of being insensitive to the frequency response of the experimental system, of being sensitive only to noise at the offset frequency, and of allowing systematic effects to be more cleanly resolved due to the simple lineshape.

  10. Emitter frequency refinement based on maximum likelihood

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Wang, Huijuan

    2015-07-01

    Frequency estimation via signal sorting is widely recognized as one of the most practical technologies in signal processing. However, the estimated frequencies via signal sorting may be inaccurate and biased due to signal fluctuation under different emitter working modes, problems of transmitter circuit, environmental noises or certain unknown interference sources. Therefore, it has become an important issue to further analyze and refine signal frequencies after signal sorting. To address the above problem, we have brought forward an iterative frequency refinement method based on maximum likelihood. Iteratively, the initial estimated signal frequency values are refined. Experimental results indicate that the refined signal frequencies are more informative than the initial ones. As another advantage of our method, noises and interference sources could be filtered out simultaneously. The efficiency and flexibility enables our method to apply in a wide application area, i.e., communication, electronic reconnaissance and radar intelligence analysis.

  11. Phononic frequency combs through nonlinear resonances

    NASA Astrophysics Data System (ADS)

    Peng, Ru-Wen; Cao, Lu-Shuai; Qi, Dong-Xiang; Wang, Mu; Schmelcher, Peter

    2015-03-01

    It is well known that optical frequency combs have become important coherent optical sources with diverging applications, ranging from optical frequency metrology to ultracold gases. In this work, we explore an analogue of optical frequency combs in driven nonlinear phononic systems, and present a mechanism for generating phononic frequency combs through nonlinear resonances. In the underlying process, a set of phonon modes is simultaneously excited by the external driving which yields frequency combs with an array of discrete and equidistant spectral lines of each nonlinearly excited phonon mode. Frequency combs through nonlinear resonance of different orders are investigated, and in particular the possibility of correlation tailoring in higher-order cases is revealed. We suggest that our results can be applied in various nonlinear acoustic processes, such as phonon harvesting, and can also be generalized to other nonlinear systems. Supported by NSF and MOST of China.

  12. Frequency Comb Generation in Superconducting Resonators

    NASA Astrophysics Data System (ADS)

    Pappas, David; Erickson, Robert; Vissers, Michael; Ku, Hsiang-Sheng

    2015-03-01

    We have generated frequency combs spanning 0.5 to 20 GHz in superconducting ? = 2 resonators at T =3 K. Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical temperature. The combs nucleate as sidebands around multiples of the pump frequency. Selection rules for the allowed frequency emission are calculated using perturbation theory, and the measured spectrum is shown to agree with the theory. Sideband spacing is measured to be accurate to 1 part in 108 The sidebands coalesce into a continuous comb structure observed to cover at least several frequency octaves. Generation of combs in this frequency range allows for unprecedented analysis of this non-linear phenomena in the time domain. We acknowledge DARPA and the NIST Quantum Information program.

  13. Wide band stepped frequency ground penetrating radar

    DOEpatents

    Bashforth, Michael B. (Buellton, CA); Gardner, Duane (Santa Maria, CA); Patrick, Douglas (Santa Maria, CA); Lewallen, Tricia A. (Ventura, CA); Nammath, Sharyn R. (Santa Barbara, CA); Painter, Kelly D. (Goleta, CA); Vadnais, Kenneth G. (Alexandria, VA)

    1996-01-01

    A wide band ground penetrating radar system (10) embodying a method wherein a series of radio frequency signals (60) is produced by a single radio frequency source (16) and provided to a transmit antenna (26) for transmission to a target (54) and reflection therefrom to a receive antenna (28). A phase modulator (18) modulates those portion of the radio frequency signals (62) to be transmitted and the reflected modulated signal (62) is combined in a mixer (34) with the original radio frequency signal (60) to produce a resultant signal (53) which is demodulated to produce a series of direct current voltage signals (66) the envelope of which forms a cosine wave shaped plot (68) which is processed by a Fast Fourier Transform unit 44 into frequency domain data (70) wherein the position of a preponderant frequency is indicative of distance to the target (54) and magnitude is indicative of the signature of the target (54).

  14. Wide band stepped frequency ground penetrating radar

    DOEpatents

    Bashforth, M.B.; Gardner, D.; Patrick, D.; Lewallen, T.A.; Nammath, S.R.; Painter, K.D.; Vadnais, K.G.

    1996-03-12

    A wide band ground penetrating radar system is described embodying a method wherein a series of radio frequency signals is produced by a single radio frequency source and provided to a transmit antenna for transmission to a target and reflection therefrom to a receive antenna. A phase modulator modulates those portions of the radio frequency signals to be transmitted and the reflected modulated signal is combined in a mixer with the original radio frequency signal to produce a resultant signal which is demodulated to produce a series of direct current voltage signals, the envelope of which forms a cosine wave shaped plot which is processed by a Fast Fourier Transform Unit 44 into frequency domain data wherein the position of a preponderant frequency is indicative of distance to the target and magnitude is indicative of the signature of the target. 6 figs.

  15. Compact Stabilized Semiconductor Laser for Frequency Metrology

    E-print Network

    Liang, W; Eliyahu, D; Dale, E; Savchenkov, A A; Seidel, D; Matsko, A B; Maleki, L

    2014-01-01

    We report on the development of a frequency modulatable 795 nm semiconductor laser based on self-injection locking to a high quality factor whispering gallery mode microresonator. The laser is characterized with residual amplitude modulation below -80 dB and frequency noise better than 300 Hz/Hz^(1/2) at offset frequencies ranging from 100 Hz to 10 MHz. The frequency modulation (FM) speed and span of the laser exceed 1 MHz and 4 GHz, respectively. Locking of the laser to Doppler-free saturated absorption resonance of 87Rb D1 line is demonstrated and frequency stability below 10^(-12) is measured for integration time spanning from 1 s to 1 day. The architecture demonstrated in this study is suitable for realization of frequency modulatable lasers at any wavelength.

  16. Frequency Control Performance Measurement and Requirements

    SciTech Connect

    Illian, Howard F.

    2010-12-20

    Frequency control is an essential requirement of reliable electric power system operations. Determination of frequency control depends on frequency measurement and the practices based on these measurements that dictate acceptable frequency management. This report chronicles the evolution of these measurements and practices. As technology progresses from analog to digital for calculation, communication, and control, the technical basis for frequency control measurement and practices to determine acceptable performance continues to improve. Before the introduction of digital computing, practices were determined largely by prior experience. In anticipation of mandatory reliability rules, practices evolved from a focus primarily on commercial and equity issues to an increased focus on reliability. This evolution is expected to continue and place increased requirements for more precise measurements and a stronger scientific basis for future frequency management practices in support of reliability.

  17. Cluster analysis of word frequency dynamics

    NASA Astrophysics Data System (ADS)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  18. Power Supply for Variable Frequency Induction Heating Using MERS Soft-Switching High Frequency Inverter

    NASA Astrophysics Data System (ADS)

    Isobe, Takanori; Kitahara, Tadayuki; Fukutani, Kazuhiko; Shimada, Ryuichi

    Variable frequency induction heating has great potential for industrial heating applications due to the possibility of achieving heating distribution control; however, large-scale induction heating with variable frequency has not yet been introduced for practical use. This paper proposes a high frequency soft-switching inverter for induction heating that can achieve variable frequency operation. One challenge of variable frequency induction heating is increasing power electronics ratings. This paper indicates that its current source type dc-link configuration and soft-switching characteristics can make it possible to build a large-scale system with variable frequency capability. A 90-kVA 150-1000Hz variable frequency experimental power supply for steel strip induction heating was developed. Experiments confirmed the feasibility of variable frequency induction heating with proposed converter and the advantages of variable frequency operation.

  19. Apparatus for measuring high frequency currents

    NASA Technical Reports Server (NTRS)

    Hagmann, Mark J. (Inventor); Sutton, John F. (Inventor)

    2003-01-01

    An apparatus for measuring high frequency currents includes a non-ferrous core current probe that is coupled to a wide-band transimpedance amplifier. The current probe has a secondary winding with a winding resistance that is substantially smaller than the reactance of the winding. The sensitivity of the current probe is substantially flat over a wide band of frequencies. The apparatus is particularly useful for measuring exposure of humans to radio frequency currents.

  20. Frequency modulation drive for a piezoelectric motor

    DOEpatents

    Mittas, Anthony (Albuquerque, NM)

    2001-01-01

    A piezoelectric motor has peak performance at a specific frequency f.sub.1 that may vary over a range of frequencies. A drive system is disclosed for operating such a motor at peak performance without feedback. The drive system consists of the motor and an ac source connected to power the motor, the ac source repeatedly generating a frequency over a range from f.sub.1 -.DELTA.x to f.sub.1 +.DELTA.y.

  1. Broadband midinfrared frequency comb with tooth scanning

    NASA Astrophysics Data System (ADS)

    Lee, Kevin F.; Mas?owski, P.; Mills, A.; Mohr, C.; Jiang, Jie; Schunemann, Peter G.; Fermann, M. E.

    2015-03-01

    Frequency combs are a massively parallel source of extremely accurate optical frequencies. Frequency combs generally operate at the visible or near-infrared wavelengths, but fundamental molecular vibrations occur at midinfrared wavelengths. We demonstrate an optically-referenced, broadband midinfrared frequency comb based on a doublyresonant optical parametric oscillator (OPO). By tuning the wavelength of the reference laser, the comb line frequencies are tuned as well. By scanning the reference wavelength, any frequency can be accessed, not just the frequencies of the base comb. Combined with our comb-resolving Fourier transform spectrometer, we can measure 200 wavenumber wide broadband absorption spectra with 200 kHz linewidth comb teeth. Our OPO is pumped by an amplified Tm fiber frequency comb, with phase-locked carrier envelope offset frequency, and repetition rate fixed by phase-locking a frequency comb line to a narrow linewidth diode laser at a telecom channel. The frequency comb is referenced to GPS by long-term stabilization of the repetition rate to a selected value using the temperature of the reference laser as the control. The resulting pump comb is about 3W of 100 fs pulses at 418 MHz repetition rate at 1950 nm. Part of the comb is used for supercontinuum generation for frequency stabilization, and the rest pumps an orientation-patterned gallium arsenide (OP-GaAs) crystal in a doubly-resonant optical parametric oscillator cavity, yielding collinear signal and idler beams from about 3 to 5.5 ?m. We verify comb scanning by resolving the 200 MHz wide absorption lines of the entire fundamental CO vibrational manifold at 11 Torr pressure.

  2. Instantaneous frequency based newborn EEG seizure characterisation

    NASA Astrophysics Data System (ADS)

    Mesbah, Mostefa; O'Toole, John M.; Colditz, Paul B.; Boashash, Boualem

    2012-12-01

    The electroencephalogram (EEG), used to noninvasively monitor brain activity, remains the most reliable tool in the diagnosis of neonatal seizures. Due to their nonstationary and multi-component nature, newborn EEG seizures are better represented in the joint time-frequency domain than in either the time domain or the frequency domain. Characterising newborn EEG seizure nonstationarities helps to better understand their time-varying nature and, therefore, allow developing efficient signal processing methods for both modelling and seizure detection and classification. In this article, we used the instantaneous frequency (IF) extracted from a time-frequency distribution to characterise newborn EEG seizures. We fitted four frequency modulated (FM) models to the extracted IFs, namely a linear FM, a piecewise-linear FM, a sinusoidal FM, and a hyperbolic FM. Using a database of 30-s EEG seizure epochs acquired from 35 newborns, we were able to show that, depending on EEG channel, the sinusoidal and piecewise-linear FM models best fitted 80-98% of seizure epochs. To further characterise the EEG seizures, we calculated the mean frequency and frequency span of the extracted IFs. We showed that in the majority of the cases (>95%), the mean frequency resides in the 0.6-3 Hz band with a frequency span of 0.2-1 Hz. In terms of the frequency of occurrence of the four seizure models, the statistical analysis showed that there is no significant difference( p = 0.332) between the two hemispheres. The results also indicate that there is no significant differences between the two hemispheres in terms of the mean frequency ( p = 0.186) and the frequency span ( p = 0.302).

  3. Frequency Dependence of Pulsed EPR Experiments

    PubMed Central

    Eaton, Sandra S.; Eaton, Gareth R.

    2009-01-01

    The frequency dependence of the signal-to-noise ratio (S/N) that is theoretically possible for pulsed EPR experiments is the same as for continuous wave experiments. To select the optimum resonance frequency or frequencies for pulsed EPR experiments it is important to consider not only S/N, but also orientation selection, depth of spin echo modulation, and intensities of forbidden transitions. Evaluation of factors involved in selecting the optimum frequency for pulsed EPR measurements of distances between spins is discussed. PMID:20148127

  4. Psychophysical tuning curves at very high frequencies

    NASA Astrophysics Data System (ADS)

    Yasin, Ifat; Plack, Christopher J.

    2005-10-01

    For most normal-hearing listeners, absolute thresholds increase rapidly above about 16 kHz. One hypothesis is that the high-frequency limit of the hearing-threshold curve is imposed by the transmission characteristics of the middle ear, which attenuates the sound input [Masterton et al., J. Acoust. Soc. Am. 45, 966-985 (1969)]. An alternative hypothesis is that the high-frequency limit of hearing is imposed by the tonotopicity of the cochlea [Ruggero and Temchin, Proc. Nat. Acad. Sci. U.S.A. 99, 13206-13210 (2002)]. The aim of this study was to test these hypotheses. Forward-masked psychophysical tuning curves (PTCs) were derived for signal frequencies of 12-17.5 kHz. For the highest signal frequencies, the high-frequency slopes of some PTCs were steeper than the slope of the hearing-threshold curve. The results also show that the human auditory system displays frequency selectivity for characteristic frequencies (CFs) as high as 17 kHz, above the frequency at which absolute thresholds begin to increase rapidly. The findings suggest that, for CFs up to 17 kHz, the high-frequency limitation in humans is imposed in part by the middle-ear attenuation, and not by the tonotopicity of the cochlea.

  5. Nanoelectromechanical systems: Nanodevice motion at microwave frequencies

    NASA Astrophysics Data System (ADS)

    Henry Huang, Xue Ming; Zorman, Christian A.; Mehregany, Mehran; Roukes, Michael L.

    2003-01-01

    It has been almost forgotten that the first computers envisaged by Charles Babbage in the early 1800s were mechanical and not electronic, but the development of high-frequency nanoelectromechanical systems is now promising a range of new applications, including sensitive mechanical charge detectors and mechanical devices for high-frequency signal processing, biological imaging and quantum measurement. Here we describe the construction of nanodevices that will operate with fundamental frequencies in the previously inaccessible microwave range (greater than 1 gigahertz). This achievement represents a significant advance in the quest for extremely high-frequency nanoelectromechanical systems.

  6. Low frequency acoustic and electromagnetic scattering

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.; Maccamy, R. C.

    1983-01-01

    This paper deals with two classes of problems arising from acoustics and electromagnetics scattering in the low frequency stations. The first class of problem is solving Helmholtz equation with Dirichlet boundary conditions on an arbitrary two dimensional body while the second one is an interior-exterior interface problem with Helmholtz equation in the exterior. Low frequency analysis show that there are two intermediate problems which solve the above problems accurate to 0(k(2) log k) where k is the frequency. These solutions greatly differ from the zero frequency approximations. For the Dirichlet problem numerical examples are shown to verify the theoretical estimates.

  7. Auditory frequency discrimination in the white rat.

    PubMed

    Talwar, S K; Gerstein, G L

    1998-12-01

    Frequency discrimination was investigated in the albino rat using a modified go/no-go positive reinforcement procedure in which subjects reported frequency increments in an ongoing series of pure tone bursts. Weber ratios (frequency difference limen/frequency) were measured from 5 to 32 kHz at 50 dB sound pressure level. A signal detection analysis of the procedure enabled a direct comparison to be made with the rat's performance in a discrete trial go/no-go task. A mean Weber ratio of 3.06+/-0.44% was measured in the frequency range 5-32 kHz. This indicates that the rat has better frequency discrimination acuity than has previously been thought. The result is discussed in the context of factors affecting performance. Among the factors that were explored we found that long training times and the specific training paradigm played important roles. In comparison to discrete trial go/no-go paradigms, rats performed much better when detecting signals from a repeating background. Frequency discrimination performance decreased linearly for tones less than 50 ms in duration. For longer tone duration performance was unaffected. The means and variability of reaction times for threshold changes of frequency were greater in comparison with supra-threshold frequency changes. PMID:9872142

  8. Subjective Frequency Ratings for 432 ASL Signs

    PubMed Central

    Mayberry, Rachel I.; Hall, Matthew L.; Zvaigzne, Meghan

    2013-01-01

    Given the importance of lexical frequency for psycholinguistic research, and the lack of comprehensive frequency data for sign languages, we collected subjective estimates of lexical frequency for 432 signs in American Sign Language. Participants were 59 deaf signers who first began to acquire ASL at ages ranging from birth to 14 years with a minimum of 10 years experience. Subjective frequency estimates were made on a scale ranging from 1 = rarely see the sign to 7 = always see the sign. Mean subjective frequency ratings for individual signs did not vary in relation to age of sign language exposure (AoLE), chronological age, or length of ASL experience. Nor did AoLE show significant effects on response time for making the ratings. However, RT was highly correlated with mean frequency rating. These results suggest that the distributions of subjective lexical frequencies are consistent across signers with varying AoLE. The implications for research practice are that subjective frequency ratings from random samples of highly experienced deaf signers can provide a reasonable measures of lexical control in sign language experiments. The appendix gives the mean and median subjective frequency rating, and the median and mean log(RT) for the ASL signs for the entire sample; the supplemental material gives these measures for three AoLE groups, Native, Early, and Late. PMID:23943581

  9. Explosive synchronization with asymmetric frequency distribution

    NASA Astrophysics Data System (ADS)

    Zhou, Wenchang; Chen, Lumin; Bi, Hongjie; Hu, Xin; Liu, Zonghua; Guan, Shuguang

    2015-07-01

    In this work, we study the synchronization in a generalized Kuramoto model with frequency-weighted coupling. In particular, we focus on the situations in which the frequency distributions of oscillators are asymmetric. For typical unimodal frequency distributions, such as Lorentzian, Gaussian, triangle, and even special Rayleigh, we find that the synchronization transition in the model generally converts from the first order to the second order as the central frequency shifts toward positive direction. We characterize two interesting coherent states in the system: In the former, two phase-locking clusters are formed, rotating with the same frequency. They correspond to those oscillators with relatively high frequencies while the oscillators with relatively small frequencies are not entrained. In the latter, two phase-locking clusters rotate with different frequencies, leading to the oscillation of the order parameter. We further conduct theoretical analysis to reveal the relation between the asymmetric frequency distribution and the conversion of synchronization type, and justify the coherent states observed in the system.

  10. Is probability of frequency too narrow?

    SciTech Connect

    Martz, H.F.

    1993-10-01

    Modern methods of statistical data analysis, such as empirical and hierarchical Bayesian methods, should find increasing use in future Probabilistic Risk Assessment (PRA) applications. In addition, there will be a more formalized use of expert judgment in future PRAs. These methods require an extension of the probabilistic framework of PRA, in particular, the popular notion of probability of frequency, to consideration of frequency of frequency, frequency of probability, and probability of probability. The genesis, interpretation, and examples of these three extended notions are discussed.

  11. Variational calculation of limit cycle and frequency

    E-print Network

    Brandt, Sebastian

    frequency and trajectory perturbatively by applying Poincaré­Lindstedt method. Then, perturbation series transmitter release dynamics integration time post­synaptic potentials at dendritic level where post

  12. Frequency content and characteristics of ventricular conduction.

    PubMed

    Tereshchenko, Larisa G; Josephson, Mark E

    2015-01-01

    The spectrum of frequencies producing the QRS complex has not been fully explored. In this manuscript we review previous studies of QRS frequency content, and discuss our novel method of the conjoint analysis of the ECG signal in six dimensions: in the domain of three space dimensions, in time domain, and in frequency domain. Orbital frequency of QRS loop is introduced as a six-dimensional characteristic of ventricular conduction, which helped to reveal inapparent ventricular conduction, and to characterize electrophysiological substrate. In this paper, we review our novel method in the historical context. PMID:26364232

  13. 47 CFR 80.377 - Frequencies for ship earth stations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Frequencies for ship earth stations. 80.377 Section 80.377 ...THE MARITIME SERVICES Frequencies Ship Earth Stations § 80.377 Frequencies for ship earth stations. The frequency band...

  14. 47 CFR 80.377 - Frequencies for ship earth stations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Frequencies for ship earth stations. 80.377 Section 80.377 ...THE MARITIME SERVICES Frequencies Ship Earth Stations § 80.377 Frequencies for ship earth stations. The frequency band...

  15. 47 CFR 80.377 - Frequencies for ship earth stations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Frequencies for ship earth stations. 80.377 Section 80.377 ...THE MARITIME SERVICES Frequencies Ship Earth Stations § 80.377 Frequencies for ship earth stations. The frequency band...

  16. 47 CFR 80.377 - Frequencies for ship earth stations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Frequencies for ship earth stations. 80.377 Section 80.377 ...THE MARITIME SERVICES Frequencies Ship Earth Stations § 80.377 Frequencies for ship earth stations. The frequency band...

  17. 47 CFR 80.377 - Frequencies for ship earth stations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Frequencies for ship earth stations. 80.377 Section 80.377 ...THE MARITIME SERVICES Frequencies Ship Earth Stations § 80.377 Frequencies for ship earth stations. The frequency band...

  18. 47 CFR 87.375 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Aeronautical Search and Rescue Stations § 87.375 Frequencies. (a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and... for assignment to aeronautical search and rescue stations for organized search and rescue training...

  19. 47 CFR 87.375 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Aeronautical Search and Rescue Stations § 87.375 Frequencies. (a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and... for assignment to aeronautical search and rescue stations for organized search and rescue training...

  20. Frequency TORCH GIRL Cohort density GOOSE CAP

    E-print Network

    Makous, Walter

    ., 2005). Like visual-world eye tracking, mouse tracking requires a display with a limited set of response alternatives. Eye tracking is sensitive to effects of lexical frequency and effects of non-displayed compe,1000], pEye tracking results Frequency: Participants fixated high

  1. Semiconductor laser gyro with optical frequency dithering

    SciTech Connect

    Prokof'eva, L P; Sakharov, V K; Shcherbakov, V V

    2014-04-28

    The semiconductor laser gyro is described, in which the optical frequency dithering implemented by intracavity phase modulation suppresses the frequency lock-in and provides the interference of multimode radiation. The sensitivity of the device amounted to 10–20 deg h{sup -1}. (laser gyroscopes)

  2. ENGLISH WORDS OF VERY HIGH FREQUENCY.

    ERIC Educational Resources Information Center

    CARD, WILLIAM; MCDAVID, VIRGINIA

    THE BIAS OF THE FREQUENCY OF THE 122 MOST COMMONLY USED ENGLISH WORDS WAS STUDIED. THE METHOD USED TO ASSEMBLE THESE DATA IS DESCRIBED FULLY. THE MOST FREQUENTLY USED WORDS WERE TAKEN FROM A DISSERTATION BY GEORGE K. MONROE, "PHONEMIC TRANSCRIPTION OF GRAPHIC POSTBASE AFFIXES IN ENGLISH," GODFREY DEWEY, "RELATIVE FREQUENCY OF ENGLISH SPEECH…

  3. Frequency Selective Volumes for Optical Spatial Filters

    SciTech Connect

    E Topsakal; JL Volakis

    2004-04-15

    A new model is proposed for modeling metallic losses at optical frequencies and is used in the analysis of Frequency Selective Surfaces (FSSs) and Volumes (FSVs). Conventional methods for simulating metallic losses are also outlined and a comparison with those models is given for a patch FSS. Measured data for a slot-ring FSS are also given for model validation.

  4. 42 CFR 488.308 - Survey frequency.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 5 2012-10-01 2012-10-01 false Survey frequency. 488.308 Section 488.308 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.308 Survey frequency. (a) Basic period. The survey agency must...

  5. 42 CFR 488.308 - Survey frequency.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false Survey frequency. 488.308 Section 488.308 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.308 Survey frequency. (a) Basic period. The survey agency must...

  6. 42 CFR 488.308 - Survey frequency.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 5 2014-10-01 2014-10-01 false Survey frequency. 488.308 Section 488.308 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.308 Survey frequency. (a) Basic period. The survey agency must...

  7. 42 CFR 488.308 - Survey frequency.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 5 2011-10-01 2011-10-01 false Survey frequency. 488.308 Section 488.308 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.308 Survey frequency. (a) Basic period. The survey agency must...

  8. 42 CFR 488.308 - Survey frequency.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 5 2013-10-01 2013-10-01 false Survey frequency. 488.308 Section 488.308 Public...) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Long-Term Care Facilities § 488.308 Survey frequency. (a) Basic period. The survey agency must...

  9. 47 CFR 90.613 - Frequencies available.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies available. 90.613 Section 90.613 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Regulations Governing Licensing and Use of Frequencies in the 806-824, 851-869, 896-901, and 935-940 MHz Bands...

  10. 47 CFR 87.241 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 87.241 Section 87.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Multicom Stations § 87.241 Frequencies. (a) 121.500 MHz: emergency and distress only; (b)...

  11. 47 CFR 87.375 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Aeronautical Search and Rescue Stations § 87.375 Frequencies. (a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and... for assignment to aeronautical search and rescue stations for organized search and rescue training...

  12. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a... available to serve domestic routes, except that the frequency 136.750 MHz is available only to aeronautical... be assigned to aeronautical enroute stations without regard to the restrictions contained in §...

  13. 47 CFR 87.241 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies. 87.241 Section 87.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Multicom Stations § 87.241 Frequencies. (a) 121.500 MHz: emergency and distress only; (b)...

  14. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a... available to serve domestic routes, except that the frequency 136.750 MHz is available only to aeronautical... aeronautical enroute stations without regard to the restrictions contained in § 87.261 (c) and (d). (5)...

  15. 47 CFR 87.375 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Aeronautical Search and Rescue Stations § 87.375 Frequencies. (a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and... for assignment to aeronautical search and rescue stations for organized search and rescue training...

  16. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a... available to serve domestic routes, except that the frequency 136.750 MHz is available only to aeronautical... be assigned to aeronautical enroute stations without regard to the restrictions contained in §...

  17. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Aeronautical Enroute and Aeronautical Fixed Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a... available to serve domestic routes, except that the frequency 136.750 MHz is available only to aeronautical... be assigned to aeronautical enroute stations without regard to the restrictions contained in §...

  18. 47 CFR 87.375 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Aeronautical Search and Rescue Stations § 87.375 Frequencies. (a) The frequency 123.100 MHz is available for assignment to aeronautical search and rescue stations for actual search and rescue missions. Each search and... for assignment to aeronautical search and rescue stations for organized search and rescue training...

  19. 47 CFR 87.241 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.241 Section 87.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Multicom Stations § 87.241 Frequencies. (a) 121.500 MHz: emergency and distress only; (b)...

  20. 47 CFR 87.241 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies. 87.241 Section 87.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Multicom Stations § 87.241 Frequencies. (a) 121.500 MHz: emergency and distress only; (b)...

  1. 47 CFR 87.241 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies. 87.241 Section 87.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Multicom Stations § 87.241 Frequencies. (a) 121.500 MHz: emergency and distress only; (b)...

  2. 47 CFR 87.279 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Aeronautical Enroute Stations, Aeronautical Fixed Stations, and Aircraft Data Link Land Test Stations Aeronautical Fixed Stations § 87.279 Frequencies. (a) United States (except Alaska). The applicant must request... only be licensed in conjunction with licenses for use of the aeronautical enroute frequencies...

  3. Exploring the limits of frequency lowering

    PubMed Central

    Souza, Pamela E.; Arehart, Kathryn H.; Kates, James M.; Croghan, Naomi B.H.; Gehani, Namita

    2013-01-01

    Objective This study examined how frequency lowering affected sentence intelligibility and quality, for adults with postlingually acquired, mild-to-moderate hearing loss. Method Listeners included adults aged 60–92 years with sloping sensorineural loss and a control group of similarly-aged adults with normal hearing. Sentences were presented in quiet and babble at a range of signal-to-noise ratios. Intelligibility and quality were measured with varying amounts of frequency lowering, implemented using a form of frequency compression. Results Moderate amounts of compression, particularly with high cutoff frequencies, had minimal effects on intelligibility. Listeners with the greatest high-frequency hearing loss showed the greatest benefit. Sentence intelligibility decreased with more compression. Listeners were more affected by a given set of parameters in noise. In quiet, any amount of compression resulted in lower speech quality for most listeners, with the greatest degradation for listeners with better high-frequency hearing. Quality ratings were lower with background noise, and in noise the effect of changing compression parameters was small. Conclusions The benefits of frequency lowering in adults were affected by the compression parameters as well as individual hearing thresholds. Data are consistent with the idea that frequency lowering can be viewed in terms of an improved audibility vs increased distortion tradeoff. PMID:23785188

  4. Slender beams vibrations: Frequency jumps at buckling

    E-print Network

    Neukirch, Sébastien

    Slender beams vibrations: Frequency jumps at buckling S. Neukirch, J. Frelat, C. Maurini d controlled force vibrations slender elastic beam in the plane Influence of F, D on the frequencies ? #12.10 0.12 0.14 8 #12;Kirchhoff equations apply to : - slender bodies - not too bent 9 short review #12;F

  5. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequency assignments. 101.147 Section 101.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.147 Frequency assignments. Link to an amendment published at 76 FR 59573, Sept. 27, 2011....

  6. 47 CFR 101.147 - Frequency assignments.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequency assignments. 101.147 Section 101.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.147 Frequency assignments. Link to an amendment published at 77 FR 54434, Sept. 5, 2012....

  7. 47 CFR 101.107 - Frequency tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Heterodyne microwave radio systems may be authorized at a somewhat less restrictive frequency tolerance (up... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequency tolerance. 101.107 Section 101.107 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED...

  8. 47 CFR 101.507 - Frequency stability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequency stability. 101.507 Section 101.507 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.507 Frequency stability. The...

  9. 47 CFR 101.507 - Frequency stability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequency stability. 101.507 Section 101.507 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.507 Frequency stability. The...

  10. 23 CFR 650.311 - Inspection frequency.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Inspection frequency. 650.311 Section 650.311 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.311 Inspection frequency. (a) Routine inspections. (1) Inspect each...

  11. Detection and frequency tracking of chirping signals

    SciTech Connect

    Elliott, G.R.; Stearns, S.D.

    1990-08-01

    This paper discusses several methods to detect the presence of and track the frequency of a chirping signal in broadband noise. The dynamic behavior of each of the methods is described and tracking error bounds are investigated in terms of the chirp rate. Frequency tracking and behavior in the presence of varying levels of noise are illustrated in examples. 11 refs., 29 figs.

  12. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...frequency band is shared with stations in the earth-exploration satellite service. ...is shared with space stations (space to earth) in the fixed-satellite service...5) This frequency band is shared with earth stations (earth to space) in the...

  13. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...frequency band is shared with stations in the earth-exploration satellite service. ...is shared with space stations (space to earth) in the fixed-satellite service...5) This frequency band is shared with earth stations (earth to space) in the...

  14. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...frequency band is shared with stations in the earth-exploration satellite service. ...is shared with space stations (space to earth) in the fixed-satellite service...5) This frequency band is shared with earth stations (earth to space) in the...

  15. Nonthermal processing by radio frequency electric fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radio frequency electric fields (RFEF) processing is relatively new and has been shown to inactivate bacteria in apple juice, orange juice and apple cider at moderately low temperatures. Key equipment components of the process include a radio frequency power supply and a treatment chamber that is ca...

  16. 47 CFR 78.18 - Frequency assignments.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Frequency assignments. 78.18 Section 78.18 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Applications and Licenses § 78.18 Frequency assignments. (a) The Cable Television Relay Service is assigned the band of...

  17. 2014 Amplifier -1 FREQUENCY RESPONSE OF

    E-print Network

    Gustafsson, Torgny

    2014 Amplifier - 1 FREQUENCY RESPONSE OF AN AUDIO AMPLIFIER The objectives of this experiment are amplifier · To thoroughly bore you APPARATUS: Audio Amplifier (Circuit Chip), Computer with FFTScope software, Speaker, Power supply, Interconnecting Cables good high fidelity amplifier will have frequency

  18. 47 CFR 90.311 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Authorization in the Band 470-512 MHz (UHF-TV Sharing) § 90.311 Frequencies. (a) Except as provided for in § 90.315 and except for those frequencies...

  19. 47 CFR 90.311 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Authorization in the Band 470-512 MHz (UHF-TV Sharing) § 90.311 Frequencies. (a) Except as provided for in § 90.315 and except for those frequencies...

  20. 47 CFR 90.311 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Authorization in the Band 470-512 MHz (UHF-TV Sharing) § 90.311 Frequencies. (a) Except as provided for in § 90.315 and except for those frequencies...

  1. 47 CFR 90.311 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Authorization in the Band 470-512 MHz (UHF-TV Sharing) § 90.311 Frequencies. (a) Except as provided for in § 90.315 and except for those frequencies...

  2. 47 CFR 90.311 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Authorization in the Band 470-512 MHz (UHF-TV Sharing) § 90.311 Frequencies. (a) Except as provided for in § 90.315 and except for those frequencies...

  3. Precise Phase Comparator for Nearly Equal Frequencies

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S.; Adams, W. A.

    1982-01-01

    New circuit precisely compares phases of two RF signals nearly equal in frequency, such as two hydrogen-maser frequency standards. Measuring circuit minimizes interactions between two sources. Also stabilized against thermal effects and against noise that could produce erroneous readings. Heat sinking, buffer amplifiers, and low-noise zero-crossing detector make picosecond precision possible.

  4. 47 CFR 101.101 - Frequency availability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequency availability. 101.101 Section 101.101 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.101 Frequency availability. Frequencyband (MHz) Radio service Commoncarrier (Part 101)...

  5. 47 CFR 74.602 - Frequency assignment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Frequency assignment. 74.602 Section 74.602 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary Stations § 74.602 Frequency assignment....

  6. 47 CFR 74.602 - Frequency assignment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Frequency assignment. 74.602 Section 74.602 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Television Broadcast Auxiliary Stations § 74.602 Frequency assignment....

  7. Amplitude Frequency Response Measurement: A Simple Technique

    ERIC Educational Resources Information Center

    Satish, L.; Vora, S. C.

    2010-01-01

    A simple method is described to combine a modern function generator and a digital oscilloscope to configure a setup that can directly measure the amplitude frequency response of a system. This is achieved by synchronously triggering both instruments, with the function generator operated in the "Linear-Sweep" frequency mode, while the oscilloscope…

  8. 47 CFR 87.529 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies. 87.529 Section 87.529 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Automatic Weather Stations (AWOS/ASOS) § 87.529 Frequencies. Prior to submitting an application,...

  9. 47 CFR 87.529 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies. 87.529 Section 87.529 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Automatic Weather Stations (AWOS/ASOS) § 87.529 Frequencies. Prior to submitting an application,...

  10. 47 CFR 87.529 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies. 87.529 Section 87.529 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Automatic Weather Stations (AWOS/ASOS) § 87.529 Frequencies. Prior to submitting an application,...

  11. 47 CFR 87.529 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies. 87.529 Section 87.529 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Automatic Weather Stations (AWOS/ASOS) § 87.529 Frequencies. Prior to submitting an application,...

  12. 47 CFR 87.529 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies. 87.529 Section 87.529 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Automatic Weather Stations (AWOS/ASOS) § 87.529 Frequencies. Prior to submitting an application,...

  13. Multi-dimensional ultra-high frequency passive radio frequency identification tag antenna designs

    E-print Network

    Delichatsios, Stefanie Alkistis

    2006-01-01

    In this thesis, we present the design, simulation, and empirical evaluation of two novel multi-dimensional ultra-high frequency (UHF) passive radio frequency identification (RFID) tag antennas, the Albano-Dipole antenna ...

  14. Optimal Periodic Training Signal for Frequency Offset Estimation in Frequency Selective Fading

    E-print Network

    Minn, Hlaing

    signal statistics. The optimal training structure with optimal training signals achieves substantial periodic training sig- nal design for frequency offset estimation in frequency selective multipath Rayleigh, the optimal periodic training signal structure (the optimal location of identical training sub

  15. Physical origin of the frequency shifts in cesium beam frequency standards: Related environmental sensitivity

    NASA Technical Reports Server (NTRS)

    Audoin, Claude; Dimarcq, N.; Giordano, V.; Viennet, J.

    1990-01-01

    When observed in a cesium beam frequency standard, the hyperfine transition frequency of the atoms differs slightly from the invariant transition frequency of the unperturbed atoms at rest. The various physical and technical origins of the frequency offsets are stated. They relate to fundamental physical effects, to the method of probing the atomic resonance and to the frequency control of the slaved oscillator. The variation of the frequency offsets under a change of the value of the internal operating characteristics is considered. The sensitivity to a change of the magnetic induction, the microwave power, and the temperature is given. A comparison is made of the sensitivity of cesium beam frequency standards of the commercially available type, making use of magnetic state selection, and of devices under study, in which the state preparation and detection is accomplished optically. The pathways between the external stimuli and the physical origin of the frequency offsets are specified.

  16. Evaluation of nonlinear frequency compression: clinical outcomes.

    PubMed

    Glista, Danielle; Scollie, Susan; Bagatto, Marlene; Seewald, Richard; Parsa, Vijay; Johnson, Andrew

    2009-01-01

    This study evaluated prototype multichannel nonlinear frequency compression (NFC) signal processing on listeners with high-frequency hearing loss. This signal processor applies NFC above a cut-off frequency. The participants were hearing-impaired adults (13) and children (11) with sloping, high-frequency hearing loss. Multiple outcome measures were repeated using a modified withdrawal design. These included speech sound detection, speech recognition, and self-reported preference measures. Group level results provide evidence of significant improvement of consonant and plural recognition when NFC was enabled. Vowel recognition did not change significantly. Analysis of individual results allowed for exploration of individual factors contributing to benefit received from NFC processing. Findings suggest that NFC processing can improve high frequency speech detection and speech recognition ability for adult and child listeners. Variability in individual outcomes related to factors such as degree and configuration of hearing loss, age of participant, and type of outcome measure. PMID:19504379

  17. Nonlinear transmission spectroscopy with dual frequency combs

    NASA Astrophysics Data System (ADS)

    Glenn, Rachel; Mukamel, Shaul

    2014-08-01

    We show how two frequency combs E1, E2 can be used to measure single-photon, two-photon absorption (TPA), and Raman resonances in a molecule with three electronic bands, by detecting the radio frequency modulation of the nonlinear transmission signal. Some peaks are independent of the carrier frequency of the comb and others shift with that frequency and have a width close to the comb width. TPA and Raman resonances independent of the carrier frequency are selected by measuring the transmission signal ˜E12E22 and the single-photon resonances are selected by measuring the transmission signal ˜E13E2. Sinusoidal spectral phase shaping strongly affects the TPA, but not the Raman resonances.

  18. Nonlinear transmission spectroscopy with dual frequency combs

    E-print Network

    Glenn, Rachel

    2014-01-01

    We show how two frequency combs $\\mathcal{E}_1$, $\\mathcal{E}_2$ can be used to measure single-photon, two-photon absorption (TPA), and Raman resonances in a molecule with three electronic bands, by detecting the radio frequency modulation of the nonlinear transmission signal. Some peaks are independent of the carrier frequency of the comb and others shift with that frequency and have a width close to the comb width. TPA and Raman resonances independent of the carrier frequency are selected by measuring the transmission signal $\\sim\\mathcal{E}_1^2 \\mathcal{E}_2^2$ and the single-photon resonances are selected by measuring the transmission signal $\\sim\\mathcal{E}_1^3\\mathcal{E}_2$. Sinusoidal spectral phase shaping strongly affects the TPA, but not the Raman resonances.

  19. Metal mesh resonant filters for terahertz frequencies.

    PubMed

    Melo, Arline M; Kornberg, Mariano A; Kaufmann, Pierre; Piazzetta, Maria H; Bortolucci, Emílio C; Zakia, Maria B; Bauer, Otto H; Poglitsch, Albrecht; da Silva, Alexandre M P Alves

    2008-11-10

    The interest in terahertz photometric and imaging measurements has motivated the development of bandpass resonant filters to be coupled to multiple-pixel devices such as bolometer arrays. Resonant grids are relatively simple to fabricate, exhibiting high transmission at the central frequency, a narrow bandpass, and good rejection of the side frequencies of the spectrum. We have fabricated filters centered at different frequencies between 0.4 and 10 THz, using photolithography and electroforming techniques. Transmission measurements have shown center frequencies and bandwidths close to the design predictions. The performance of the filters was found not to be critically dependent on small physical deformations in the mesh, becoming more noticeable at higher frequencies (i.e., for smaller physical sizes). Wider bandwidths, needed to attain higher sensitivities in the continuum, were obtained by changing the design parameters for filters at 2 and 3 THz. PMID:19002231

  20. All-optically stabilized frequency comb

    NASA Astrophysics Data System (ADS)

    Okubo, Sho; Gunji, Kenta; Onae, Atsushi; Schramm, Malte; Nakamura, Keisuke; Hong, Feng-Lei; Hattori, Toshiaki; Hosaka, Kazumoto; Inaba, Hajime

    2015-12-01

    We present an all-optically stabilized, erbium-doped mode-locked fiber laser with an optically pumped ytterbium-doped fiber. The mode-locked fiber laser has two frequency-control actuators that are pump laser powers for erbium-doped and ytterbium-doped fibers. We investigate the frequency-control characteristics of the mode-locked laser and find that the fixed points for the two actuators are sufficiently apart from each other, realizing the simultaneous phase locking of the repetition and carrier envelope offset frequencies. We describe a long-term frequency measurement of an acetylene-stabilized laser at 1542 nm using an all-optically stabilized frequency comb.

  1. Reference frequency transmission over optical fiber

    NASA Technical Reports Server (NTRS)

    Lutes, G.; Kirk, A.

    1986-01-01

    A 100-MHz reference frequency from a hydrogen maser frequency standard has been transmitted via optical fiber over a 14-km distance with a measured stability of 1.5 X 10 to the-15 power for 1000 seconds averaging time. This capability was demonstrated in a frequency distribution experiment performed in April, 1986. The reference frequency was transmitted over a single-mode fiber-optic link from Deep Space Station (DSS) 13 to DSS 12 and back. The background leading up to the experiment and the significance of stable reference frequency distribution in the Deep Space Network (DSN) is discussed. Also described are the experiment, including the fiber-optic link, the measurement method and equipment, and finally the results of the experiment.

  2. Turbulence in unsteady flow at high frequencies

    NASA Astrophysics Data System (ADS)

    Kuhn, Gary D.

    1990-01-01

    Turbulent flows subjected to oscillations of the mean flow were simulated using a large-eddy simulation computer code for flow in a channel. The objective of the simulations was to provide better understanding of the effects of time-dependent disturbances on the turbulence of a boundary layer and of the underlying physical phenomena regarding the basic interaction between the turbulence and external disturbances. The results confirmed that turbulence is sensitive to certain ranges of frequencies of disturbances. However, no direct connection was found between the frequency of imposed disturbances and the characteristic 'burst' frequency of turbulence. New insight into the nature of turbulence at high frequencies was found. Viscous phenomena near solid walls were found to be the dominant influence for high-frequency perturbations.

  3. Human teeth model using photoacoustic frequency response

    NASA Astrophysics Data System (ADS)

    El-Sharkawy, Yasser H.; El-Sherif, Ashraf F.

    2012-03-01

    In this paper, a novel photo-acoustic technique modality utilizing a frequency- modulated Q-switch Nd:YAG laser at 1064 nm and coherent frequency domain signal processing is introduced for impulse and frequency responses of biological tissues. We present a photoacoustic technique to monitor the temporal behavior of temperature and pressure in an excised sample of human teeth after either a single laser pulse or during multiple laser pulses at pulse repetition frequencies (PRF) from 5 Hz to 100 Hz. Knowledge of the dynamic characteristics of structural elements often means the difference between normal and abnormal tissue. The determination of the resonance characteristics of structures is termed "modal analysis." The results of our study suggest that it is possible to identify the impulse, frequency response and resonance modes of simplified human teeth. This data provided a powerful tool to differentiate between normal and decay teeth.

  4. Low-frequency oscillations in Hall thrusters

    NASA Astrophysics Data System (ADS)

    Wei, Li-Qiu; Han, Liang; Yu, Da-Ren; Guo, Ning

    2015-05-01

    In this paper, we summarize the research development of low-frequency oscillations in the last few decades. The findings of physical mechanism, characteristics and stabilizing methods of low-frequency oscillations are discussed. It shows that it is unreasonable and incomplete to model an ionization region separately to analyze the physical mechanism of low-frequency oscillations. Electro-dynamics as well as the formation conditions of ionization distribution play an important role in characteristics and stabilizing of low-frequency oscillations. Understanding the physical mechanism and characteristics of low- frequency oscillations thoroughly and developing a feasible method stabilizing this instability are still important research subjects. Project supported by the National Natural Science Foundation of China (Grant No. 51477035), the Fundamental Research Funds for the Central Universities, China (Grant No. HIT.NSRIF 2015064), and the Open Research Fund Program of State Key Laboratory of Cryogenic Vacuum Technology and Physics, China (Grant No. ZDK201304).

  5. Variable frequency iteration MPPT for resonant power converters

    SciTech Connect

    Zhang, Qian; Bataresh, Issa; Chen, Lin

    2015-06-30

    A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial frequency that is used to set a first reduced frequency search range centered or bounded by the maximum power initial frequency including at least a first additional bounding frequency. A second iteration includes calculating first and second center frequencies by averaging adjacent frequent values in the first reduced frequency search range and measuring second power values at the first and second center frequencies. The switching frequency is determined from measured power values including the second power values.

  6. 78 FR 45479 - Frequency Response and Frequency Bias Setting Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ...The Commission proposes to approve Reliability Standard BAL- 003-1 (Frequency Response and Frequency Bias Setting), submitted by the North American Electric Reliability Corporation, the Commission- certified Electric Reliability Organization. The proposed Reliability Standard defines the necessary amount of frequency response needed for reliable operations for each Balancing Authority within......

  7. E4.18 Radio Frequency Electronics Copyright 2006 Dr Stepan Lucyszyn Frequency Spectrum

    E-print Network

    Papavassiliou, Christos

    Applications Phased-array radar Electronic warfare (e.g. Electronic Surveillance Measures, ECM, ECCM, decoysE4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn Frequency Spectrum and Applications #12;E4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn #12;E4.18 Radio

  8. Beyond Phonotactic Frequency: Presentation Frequency Effects Word Productions in Specific Language Impairment

    ERIC Educational Resources Information Center

    Plante, Elena; Bahl, Megha; Vance, Rebecca; Gerken, LouAnn

    2011-01-01

    Phonotactic frequency effects on word production are thought to reflect accumulated experience with a language. Here we demonstrate that frequency effects can also be obtained through short-term manipulations of the input to children. We presented children with nonwords in an experiment that systematically manipulated English phonotactic frequency

  9. The Relationship between Word Frequency and Reading Vocabulary Using Six Metrics of Frequency.

    ERIC Educational Resources Information Center

    Graves, Michael F.; And Others

    1987-01-01

    The relationship between word frequency and reading vocabulary was investigated, with particular attention to the lognormal model of word frequency distribution and the concept of family frequency. Subjects were 576 elementary and secondary school students. The effects of grade, ability, and gender were also investigated. Results are discussed.…

  10. The Low-Frequency Encoding Disadvantage: Word Frequency Affects Processing Demands

    ERIC Educational Resources Information Center

    Diana, Rachel A.; Reder, Lynne M.

    2006-01-01

    Low-frequency words produce more hits and fewer false alarms than high-frequency words in a recognition task. The low-frequency hit rate advantage has sometimes been attributed to processes that operate during the recognition test (e.g., L. M. Reder et al., 2000). When tasks other than recognition, such as recall, cued recall, or associative…

  11. 164-GHz MMIC HEMT Frequency Doubler

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Radisic, Vesna; Micovic, Miro; Hu, Ming; Janke, Paul; Ngo, Catherine; Nguyen, Loi; Morgan, Matthew

    2003-01-01

    A monolithic microwave integrated circuit (MMIC) that includes a high-electron-mobility transistor (HEMT) has been developed as a prototype of improved frequency doublers for generating signals at frequencies greater than 100 GHz. Signal sources that operate in this frequency range are needed for a variety of applications, notably including general radiometry and, more specifically, radiometric remote sensing of the atmosphere. Heretofore, it has been common practice to use passive (diode-based) frequency multipliers to obtain frequencies greater than 100 GHz. Unfortunately, diode-based frequency multipliers are plagued by high DC power consumption and low conversion efficiency. Moreover, multiplier diodes are not easily integrated with such other multiplier-circuit components as amplifiers and oscillators. The goals of developing the present MMIC HEMT frequency doubler were (1) to utilize the HEMT as an amplifier to increase conversion efficiency (more precisely, to reduce conversion loss), thereby increasing the output power for a given DC power consumption or, equivalently, reducing the DC power consumption for a given output power; and (2) to provide for the integration of amplifier and oscillator components on the same chip. The MMIC frequency doubler (see Figure 1) contains an AlInAs/GaInAs/InP HEMT biased at pinch-off to make it function as a class-B amplifier (meaning that it conducts in half-cycle pulses). Grounded coplanar waveguides (GCPWs) are used as impedance-matching transmission lines. Air bridges are placed at discontinuities to suppress undesired slot electromagnetic modes. Another combination of GCPWs also serves both as a low-pass filter to suppress undesired oscillations at frequencies below 60 GHz and as a DC blocker. Large decoupling capacitors and epitaxial resistors are added in the drain and gate lines to suppress bias oscillations. At the output terminal, the fundamental frequency is suppressed by a quarter-wave open stub, which presents a short circuit at the fundamental frequency and an open circuit at the second harmonic. At an input power of 7 mW, the output power and conversion loss at an output frequency of 164 GHz were found to be 5 dBm (approximately equal to 3.2 mW) and 2 dB, respectively, with a 3-dB output-power bandwidth of 14 GHz. This is the best performance reported to date for an MMIC HEMT frequency doubler above 100 GHz.

  12. High frequency pressure oscillator for microcryocoolers

    NASA Astrophysics Data System (ADS)

    Vanapalli, S.; ter Brake, H. J. M.; Jansen, H. V.; Zhao, Y.; Holland, H. J.; Burger, J. F.; Elwenspoek, M. C.

    2008-04-01

    Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented with the aim to power a micropulse tube cryocooler operating between 300 and 80K, delivering a cooling power of 10mW. Piezoelectric actuators operate efficiently at high frequencies and have high power density making them good candidates as drivers for high frequency pressure oscillator. The pressure oscillator described in this work consists of a membrane driven by a piezoelectric actuator. A pressure ratio of about 1.11 was achieved with a filling pressure of 2.5MPa and compression volume of about 22.6mm3 when operating the actuator with a peak-to-peak sinusoidal voltage of 100V at a frequency of 1kHz. The electrical power input was 2.73W. The high pressure ratio and low electrical input power at high frequencies would herald development of microminiature cryocoolers.

  13. Frequency division using a micromechanical resonance cascade

    NASA Astrophysics Data System (ADS)

    Qalandar, K. R.; Strachan, B. S.; Gibson, B.; Sharma, M.; Ma, A.; Shaw, S. W.; Turner, K. L.

    2014-12-01

    A coupled micromechanical resonator array demonstrates a mechanical realization of multi-stage frequency division. The mechanical structure consists of a set of N sequentially perpendicular microbeams that are connected by relatively weak elastic elements such that the system vibration modes are localized to individual microbeams and have natural frequencies with ratios close to 1:2:⋯:2N. Conservative (passive) nonlinear inter-modal coupling provides the required energy transfer between modes and is achieved by finite deformation kinematics. When the highest frequency beam is excited, this arrangement promotes a cascade of subharmonic resonances that achieve frequency division of 2j at microbeam j for j = 1, …, N. Results are shown for a capacitively driven three-stage divider in which an input signal of 824 kHz is passively divided through three modal stages, producing signals at 412 kHz, 206 kHz, and 103 kHz. The system modes are characterized and used to delineate the range of AC input voltages and frequencies over which the cascade occurs. This narrow band frequency divider has simple design rules that are scalable to higher frequencies and can be extended to a larger number of modal stages.

  14. Frequency Approach to Analysis of ESD Pulse

    NASA Astrophysics Data System (ADS)

    Baran, Janusz; Sroka, Jan

    The paper concerns calibration of generators for simulation of the Human-Metal Electrostatic Discharge (ESD) according to the IEC 61000-4-2 standard. It is shown that analysis of the ESD pulse in the frequency domain can be an indication if omitting the frequency considerations in calibration of ESD guns is acceptable. The calibration setup consists of a target (current converter), attenuator, coaxial cable and a wideband, single shot oscilloscope. It is much easier to use only a low frequency model of such a measurement path setup than consider a high frequency model. If, however, a high frequency treatment is indispensable, then a frequency dependent transfer impedance of the measurement path and approximation of the oscilloscope frequency response with an infinite impulse response discrete time filter are adequate tools. Comparison of power spectral densities (PSD) of theoretical pulses, measured pulses as well as the measurement path noise gives a good criterion for specifying minimal bandwidth of a setup required for reliable calibration of a given ESD gun. This paper is a resume of previous papers of the authors, in which these issues were presented in details.

  15. Frequency division using a micromechanical resonance cascade

    SciTech Connect

    Qalandar, K. R. Gibson, B.; Sharma, M.; Ma, A.; Turner, K. L.; Strachan, B. S.; Shaw, S. W.

    2014-12-15

    A coupled micromechanical resonator array demonstrates a mechanical realization of multi-stage frequency division. The mechanical structure consists of a set of N sequentially perpendicular microbeams that are connected by relatively weak elastic elements such that the system vibration modes are localized to individual microbeams and have natural frequencies with ratios close to 1:2:?:2{sup N}. Conservative (passive) nonlinear inter-modal coupling provides the required energy transfer between modes and is achieved by finite deformation kinematics. When the highest frequency beam is excited, this arrangement promotes a cascade of subharmonic resonances that achieve frequency division of 2{sup j} at microbeam j for j?=?1, …, N. Results are shown for a capacitively driven three-stage divider in which an input signal of 824?kHz is passively divided through three modal stages, producing signals at 412?kHz, 206?kHz, and 103?kHz. The system modes are characterized and used to delineate the range of AC input voltages and frequencies over which the cascade occurs. This narrow band frequency divider has simple design rules that are scalable to higher frequencies and can be extended to a larger number of modal stages.

  16. Direct Frequency Comb Spectroscopy of Alkali Atoms

    NASA Astrophysics Data System (ADS)

    Pradhananga, Trinity; Palm, Christopher; Nguyen, Khoa; Guttikonda, Srikanth; Kimball, Derek Jackson

    2011-11-01

    We are using direct frequency comb spectroscopy to study transition frequencies and excited state hyperfine structure in potassium and rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the atomic vapor of interest. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. The thermal motion of the atoms in the vapor cell actually eliminates the need to fine-tune the offset frequency and repetition rate, alleviating a somewhat challenging requirement for spectroscopy of cold atoms. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

  17. Characterization of frequency noise on a broadband infrared frequency comb using optical heterodyne techniques.

    PubMed

    Kim, K; Nicholson, J W; Yan, M; Knight, J C; Newbury, N R; Diddams, S A

    2007-12-24

    We measure the frequency noise across a Cr:forsterite infrared frequency comb through the optical heterodyne beat of different comb teeth against stable continuous wave (CW) lasers. This sensitive measurement shows strong correlations of the frequency noise between spectral components of the comb, relative to a fixed optical frequency near the 1.3 micron carrier of the Cr:forsterite laser. The correlated frequency fluctuations are shown to arise from amplitude noise on the pump laser. We also report a preliminary comparison of excess noise that occurs during supercontinuum generation in both highly nonlinear fiber and an extruded glass microstructured fiber. PMID:19551068

  18. Compact frequency-modulation Q-switched single-frequency fiber laser at 1083 nm

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanfei; Feng, Zhouming; Xu, Shanhui; Mo, Shupei; Yang, Changsheng; Li, Can; Gan, Jiulin; Chen, Dongdan; Yang, Zhongmin

    2015-12-01

    A compact frequency-modulation Q-switched single-frequency fiber laser is demonstrated at 1083 nm. The short linear resonant cavity consists of a 12 mm long homemade Yb3+-doped phosphate fiber and a pair of fiber Bragg gratings (FBGs) in which the Q-switching and the frequency excursion is achieved by a tensile-induced period modulation. Over 375 MHz frequency-tuning range is achieved with a modulation frequency varying from tens to hundreds of kilohertz. The highest peak power of the output pulse reaching 6.93 W at the repetition rate of 10 kHz is obtained.

  19. Scaling of Yb-Fiber Frequency Combs

    NASA Astrophysics Data System (ADS)

    Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

    2010-06-01

    Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

  20. When does word frequency influence written production?

    PubMed Central

    Baus, Cristina; Strijkers, Kristof; Costa, Albert

    2013-01-01

    The aim of the present study was to explore the central (e.g., lexical processing) and peripheral processes (motor preparation and execution) underlying word production during typewriting. To do so, we tested non-professional typers in a picture typing task while continuously recording EEG. Participants were instructed to write (by means of a standard keyboard) the corresponding name for a given picture. The lexical frequency of the words was manipulated: half of the picture names were of high-frequency while the remaining were of low-frequency. Different measures were obtained: (1) first keystroke latency and (2) keystroke latency of the subsequent letters and duration of the word. Moreover, ERPs locked to the onset of the picture presentation were analyzed to explore the temporal course of word frequency in typewriting. The results showed an effect of word frequency for the first keystroke latency but not for the duration of the word or the speed to which letter were typed (interstroke intervals). The electrophysiological results showed the expected ERP frequency effect at posterior sites: amplitudes for low-frequency words were more positive than those for high-frequency words. However, relative to previous evidence in the spoken modality, the frequency effect appeared in a later time-window. These results demonstrate two marked differences in the processing dynamics underpinning typing compared to speaking: First, central processing dynamics between speaking and typing differ already in the manner that words are accessed; second, central processing differences in typing, unlike speaking, do not cascade to peripheral processes involved in response execution. PMID:24399980

  1. Frequency response in short thermocouple wires

    NASA Technical Reports Server (NTRS)

    Forney, L. J.; Meeks, E. L.; Ma, J.; Fralick, G. C.

    1992-01-01

    Theoretical expressions are derived for the steady state frequency response of a thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for a nonuniform wire with unequal material properties and wire diameters across the junction. The amplitude ratio at low frequency omega approaches 0 agrees with the results of Scadron and Warshawsky (1952) for a steady state temperature distribution. Moreover, the frequency response for a nonuniform wire in the limit of infinite length l approaches infinity is shown to reduce to a simple expression that is analogous to the classic first order solution for a thermocouple wire with uniform properties. Theoretical expressions are also derived for the steady state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire and a two material wire with unequal material properties across the junction. For the case of a one material supported wire, an exact solution is derived which compares favorably with an approximate expression that only matches temperatures at the support junction. Moreover, for the case of a two material supported wire, an analytical expression is derived that closely correlates numerical results. Experimental measurements are made for the steady state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire (type K) and a two material wire (type T) with unequal material properties across the junction. The data for the amplitude ratio and phase angle are correlated to within 10 pct. with the theoretical predictions of Forney and Fralick (1991). This is accomplished by choosing a natural frequency omega sub n for the wire data to correlate the first order response at large gas temperature frequencies. It is found that a large bead size, however, will increase the amplitude ratio at low frequencies but decrease the natural frequency of the wire. The phase angle data are also distorted for imperfect junctions.

  2. High power radio frequency attenuation device

    DOEpatents

    Kerns, Quentin A. (Bloomingdale, IL); Miller, Harold W. (Winfield, IL)

    1984-01-01

    A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

  3. Frequency addressable beams for land mobile communications

    NASA Technical Reports Server (NTRS)

    Thompson, J. D.; Dubellay, G. G.

    1988-01-01

    Satellites used for mobile communications need to serve large numbers of small, low cost terminals. The most important parameters affecting the capacity of such systems are the satellite equivalent isotropically radiated power (EIRP) and gain to noise temperature ratio (G/T) and available bandwidth. Satellites using frequency addressed beams provide high EIRP and G/T with high-gain antenna beams that also permit frequency reuse over the composite coverage area. Frequency addressing is easy to implement and compatible with low-cost terminals and offers higher capacity than alternative approaches.

  4. Barrier/n/n+ Varactor Frequency Multipliers

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo; Tolmunen, Timo J.; Frerking, Margaret A.; Maserjian, Joseph

    1992-01-01

    Barrier/n/n+ (BNN+) varactor diodes developed as frequency multipliers at millimeter and submillimeter wavelengths. Devices required to serve as frequency triplers or quintuplers to provide powers of order of milliwatts at frequencies from 0.1 THz to about 1 THz. Feature Mott or heterojunction barriers and back-to-back diode configuration, which make it possible to obtain symmetrical capacitance-versus-voltage characteristics with high ratio between maximum and minimum capacitances. Extension of barrier/intrinsic/n+ (BIN+) concept described in "BIN Diode for Submillimeter Wavelengths" (NPO-17258).

  5. Nanofilm thickness measurement by resonant frequencies

    NASA Astrophysics Data System (ADS)

    Latyshev, A. V.; Yushkanov, A. A.

    2015-03-01

    We report a theoretical investigation of monochromatic laser light - thin metal film interaction. The dependences of transmission, reflection and absorption coefficients of an electromagnetic wave on the incidence angle, layer thickness and effective electron collision frequency are obtained. The above coefficients are analysed in the region of resonant frequencies. The resulting formula for the transmission, reflection and absorption coefficients are found to be valid for any angles of incidence. The case of mirror boundary conditions is considered. A formula is derived for contactless measurement of the film thickness by the observed resonant frequencies.

  6. Turbine bucket natural frequency tuning rib

    DOEpatents

    Wang, John Zhiqiang (Greenville, SC); Norton, Paul Francis (Greenville, SC); Barb, Kevin Joseph (Halfmoon, NY); Jacala, Ariel Caesar-Prepena (Simpsonville, SC)

    2002-01-01

    A tuning rib is added preferably in the aft cavity of a cored turbine bucket to alter the bucket's natural frequencies. The tuning rib may be a solid rib or a segmented rib and is particularly suited for altering high order frequency modes such as 2T, 4F and 1-3S. As such, detrimental crossings of natural bucket frequencies and gas turbine stimuli can be avoided to thereby improve the reliability of a gas turbine without impacting other features of the bucket that are important to the performance of the gas turbine.

  7. Feshbach resonances in Kerr frequency combs

    NASA Astrophysics Data System (ADS)

    Matsko, Andrey B.; Maleki, Lute

    2015-01-01

    We show that both the power and repetition rate of a frequency comb generated in a nonlinear ring resonator, pumped with continuous-wave (cw) coherent light, are modulated. The modulation is brought about by the interaction of the cw background with optical pulses excited in the resonator, and occurs in resonators with nonzero high-order chromatic dispersion and wavelength-dependent quality factor. The modulation frequency corresponds to the detuning of the pump frequency from the eigenfrequency of the pumped mode in the resonator.

  8. Evaluation of a simplified Doppler frequency shifter

    NASA Astrophysics Data System (ADS)

    Marr, R. A.; Lammers, U. H. W.

    1990-09-01

    Mechanical Doppler frequency shifting of a millimeter or submillimeter wave signal provides a means to implement a sensitive and highly coherent heterodyne receiver in a laboratory system. The rotary shifter which was described by Lammers et al. (1990), is a precision-machined device suitable for use down to submillimeter wavelengths. It was found at 140 GHz, however, that the coherence of such a system is not affected by mechanical imprecision of the frequency shifter, and that the system dynamic range is only moderately affected by mechanical imprecision and by certain design simplifications. Several versions of simpler and less precise Doppler frequency shifters were built. Their performance at 140 GHz is described.

  9. Frequency(#Seedlings&Saplings) Substrate Cover (%)

    E-print Network

    Brown, Sally

    30 35 40 0-10 11-20 21-30 31-40 41-50 51-60 61-70 Frequency Basal Area Bins (m2/ha) All Species 0 5 10 15 20 25 30 35 40 0-10 11-20 21-30 31-40 41-50 51-60 60-100 Frequency Basal Area Bins (m2/ha) P. menziesii 0 5 10 15 20 25 30 35 40 45 0-10 11-20 21-30 31-40 41-50 51-60 60-100 Frequency Basa Area Bins (m2

  10. Microwave Frequency Discriminator With Sapphire Resonator

    NASA Technical Reports Server (NTRS)

    Santiago, David G.; Dick, G. John

    1994-01-01

    Cooled sapphire resonator provides ultralow phase noise. Apparatus comprises microwave oscillator operating at nominal frequency of about 8.1 GHz, plus frequency-discriminator circuit measuring phase fluctuations of oscillator output. One outstanding feature of frequency discriminator is sapphire resonator serving as phase reference. Sapphire resonator is dielectric ring resonator operating in "whispering-gallery" mode. Functions at room temperature, but for better performance, typically cooled to operating temperature of about 80 K. Similar resonator described in "Sapphire Ring Resonator for Microwave Oscillator" (NPO-18082).

  11. Frequency Response of Pressure Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Winslow, Neal A.; Carroll, Bruce F.; Setzer, Fred M.

    1996-01-01

    An experimental method for measuring the frequency response of Pressure Sensitive Paints (PSP) is presented. These results lead to the development of a dynamic correction technique for PSP measurements which is of great importance to the advancement of PSP as a measurement technique. The ability to design such a dynamic corrector is most easily formed from the frequency response of the given system. An example of this correction technique is shown. In addition to the experimental data, an analytical model for the frequency response is developed from the one dimensional mass diffusion equation.

  12. Multi-mode radio frequency device

    DOEpatents

    Gilbert, Ronald W. (Morgan Hill, CA); Carrender, Curtis Lee (Morgan Hill, CA); Anderson, Gordon A. (Benton City, WA); Steele, Kerry D. (Kennewick, WA)

    2007-02-13

    A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

  13. Limits in high efficiency quantum frequency conversion

    E-print Network

    Nicolás Quesada; J. E. Sipe

    2015-08-13

    Frequency conversion is an enabling process in many quantum information protocols. In this letter we study fundamental limits to high efficiency frequency conversion imposed by time ordering corrections. Using the Magnus expansion, we argue that these corrections, which are usually considered detrimental, can be used to increase the efficiency of conversion under certain circumstances. The corrections induce a nonlinear behaviour in the probability of upconversion as a function of the pump intensity, significantly modifying the sinusoidal Rabi oscillations that are otherwise expected. Finally, by using a simple scaling argument, we explain why cascaded frequency conversion devices attenuate time ordering corrections, allowing the construction of near ideal quantum pulse gates.

  14. A tunable and wide-range frequency-offset locking technology using external frequency modulation

    NASA Astrophysics Data System (ADS)

    Jiang, Zhikun; Feng, Yanying; Yan, Xueshu; Chen, Shu

    2015-10-01

    In order to obtain frequency-locked laser beam with widely tunable frequency- offset used in a clod atom interferometer, a frequency stabilization method using a fiber electro-optic modulator (FEOM) is proposed. In this method, the laser passing through a FEOM can be locked with a wide-range frequency-offset, avoiding the frequency and power jitter caused by internal modulation on the current or PZT at the same time. To evaluate the outcome of this method, a beat signal between the frequency-shifted laser and the laser locked by Doppler-free Dichroic Atomic Vapor Laser Lock was measured. The analysis of the experimental results shows that the frequency-offset of the laser beam, with a full width at half maximum less than 1 MHz, can be tuned from 200 MHz to 10 GHz, which successfully meets the requirements of cold atom interferometer.

  15. A low frequency radio array for space

    NASA Technical Reports Server (NTRS)

    Weiler, K. W.; Johnston, K. J.; Simon, R. S.; Dennison, B. K.; Erickson, W. C.; Kaiser, M. L.; Cane, H. V.; Desch, M. D.

    1988-01-01

    This paper considers the need for and the possibility of constructing and operating a low-frequency array in space, the Low Frequency Space Array (LFSA), which is presently in its developmental phase, to form an entirely space-based synthesis interferometer for high-resolution high-sensitivity sky surveying and source imaging over the frequency range from about 1 to about 30 MHz. It is emphasized that there is a wealth of new astronomical information to be found in the as yet unexplored frequency range below 30 MHz, the wavelengths at which only interferometry is practicable. A possible instrumental concept for an LFSA spacecraft is described together with orbits, hardware, and subsystems.

  16. Scaled models, scaled frequencies, and model fitting

    NASA Astrophysics Data System (ADS)

    Roxburgh, Ian W.

    2015-12-01

    I show that given a model star of mass M, radius R, and density profile ?(x) [x = r/R], there exists a two parameter family of models with masses Mk, radii Rk, density profile ?k(x) = ??(x) and frequencies ?kn? = ?1/2?n?, where ?,Rk/RA are scaling factors. These models have different internal structures, but all have the same value of separation ratios calculated at given radial orders n, and all exactly satisfy a frequency matching algorithm with an offset function determined as part of the fitting procedure. But they do not satisfy ratio matching at given frequencies nor phase shift matching. This illustrates that erroneous results may be obtained when model fitting with ratios at given n values or frequency matching. I give examples from scaled models and from non scaled evolutionary models.

  17. 47 CFR 87.263 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...AND SPECIAL RADIO SERVICES AVIATION SERVICES Aeronautical Enroute Stations, Aeronautical Fixed Stations, and Aircraft Data Link Land Test Stations Aeronautical Enroute Stations § 87.263 Frequencies. (a) Domestic VHF service....

  18. Protein alphabet reduction based on frequency dictionaries

    E-print Network

    Gorban, Alexander N.

    classification The bases of theoretical grouping of amino acids mentioned in literature may be attributedProtein alphabet reduction based on frequency dictionaries Misha Kudryashev with Tatyana Popova acids classifications for various classes of proteins, comparisons to functional classifications What

  19. Detecting deception via eyeblink frequency modulation

    PubMed Central

    2014-01-01

    To assess the efficacy of using eyeblink frequency modulation to detect deception about a third party, 32 participants were sent on a mission to deliver a package to an interviewer. 17 of the participants lied to the interviewer about the details of their mock mission and 15 responded truthfully. During the interview, eyeblink frequency data were collected via electromyography and recorded video. Liars displayed eyeblink frequency suppression while lying, while truth tellers exhibited an increase in eyeblink frequency during the mission relevant questioning period. The compensatory flurry of eyeblinks following deception observed in previous studies was absent in the present study. A discriminant function using eyeblink suppression to predict lying correctly classified 81.3% of cases, with a sensitivity of 88.2% and a specificity of 73.3%. This technique, yielding a reasonable sensitivity, shows promise for future testing as, unlike polygraph, it is compatible with distance technology. PMID:24688844

  20. Flood-frequency characteristics of Wisconsin streams

    USGS Publications Warehouse

    Walker, John F.; Krug, William R.

    2003-01-01

    Flood-frequency characteristics for 312 gaged sites on Wisconsin streams are presented for recurrence intervals of 2 to 100 years using flood-peak data collected through water year 2000. Equations of the relations between flood-frequency and drainage-basin characteristics were developed by multiple-regression analyses. Flood-frequency characteristics for ungaged sites on unregulated, rural streams can be estimated by use of these equations. The state was divided into five areas with similar physiographic characteristics. The most significant basin characteristics are drainage area, main-channel slope, soil permeability, storage, rainfall intensity, and forest cover. The standard error of prediction for the equation for the 100-year flood discharge ranges from 22 to 44 percent in the state. A graphical method for estimating flood-frequency characteristics of regulated streams was developed from the relation of discharge and drainage area. Graphs for the major regulated streams are presented.

  1. Security approaches for Radio Frequency Identification systems

    E-print Network

    Foley, Joseph Timothy, 1976-

    2007-01-01

    In this thesis, I explore the challenges related to the security of the Electronic Product Code (EPC) class of Radio Frequency Identification (RFID) tags and associated data. RFID systems can be used to improve supply chain ...

  2. Audio classification from time-frequency texture

    E-print Network

    Slotine, Jean-Jacques E.

    Time-frequency representations of audio signals often resemble texture images. This paper derives a simple audio classification algorithm based on treating sound spectrograms as texture images. The algorithm is inspired ...

  3. Phononic Frequency Combs via Nonlinear Resonances

    E-print Network

    Lushuai Cao; Dongxiang Qi; Ruwen Peng; Mu Wang; Peter Schmelcher

    2014-02-22

    We study the analogue of optical frequency combs in driven nonlinear phononic systems, and present a new generation mechanism for phononic frequency combs via nonlinear resonances. The nonlinear resonance refers to the simultaneous excitation of a set of phonon modes by the external driving, and thereby generated frequency combs are characterized by an array of equidistant spectral lines in the spectrum of each nonlinearly excited phonon mode. Frequency combs via nonlinear resonance of different orders are investigated, and particularly we reveal the possibility for correlation tailoring in higher order cases. The investigation contributes to potential applications in various nonlinear acoustic processes, such as harvesting phonons and generating phonon entanglements, and can also be generalized to other nonlinear systems.

  4. Frequency comb generation in quadratic nonlinear media

    E-print Network

    Ricciardi, Iolanda; Parisi, Maria; Maddaloni, Pasquale; Santamaria, Luigi; De Natale, Paolo; De Rosa, Maurizio

    2014-01-01

    Optical frequency combs are nowadays routinely used tools in a wide range of scientific and technological applications. Different techniques have been developed for generating optical frequency combs, like mode-locking in lasers and third-order interactions in microresonators, or to extend their spectral capabilities, using frequency conversion processes in nonlinear materials. Here, we experimentally demonstrate and theoretically explain the onset of optical frequency combs in a simple cavity-enhanced second-harmonic-generation system, exploiting second-order nonlinear interactions. We develop an elemental model which provides a deep physical insight into the observed dynamics. Moreover, despite the different underlying physical mechanism, the proposed model is remarkably similar to the description of third-order effects in microresonators, revealing a potential variety of new effects to be explored. Finally, exploiting a nonlinearity intrinsically stronger than the third-order one, our work lays the groundw...

  5. Phononic Frequency Combs via Nonlinear Resonances

    E-print Network

    Cao, Lushuai; Peng, Ruwen; Wang, Mu; Schmelcher, Peter

    2013-01-01

    We study the analogue of optical frequency combs in driven nonlinear phononic systems, and present a new generation mechanism for phononic frequency combs via nonlinear resonances. The nonlinear resonance refers to the simultaneous excitation of a set of phonon modes by the external driving, and thereby generated frequency combs are characterized by an array of equidistant spectral lines in the spectrum of each nonlinearly excited phonon mode. Frequency combs via nonlinear resonance of different orders are investigated, and particularly we reveal the possibility for correlation tailoring in higher order cases. The investigation contributes to potential applications in various nonlinear acoustic processes, such as harvesting phonons and generating phonon entanglements, and can also be generalized to other nonlinear systems.

  6. NO2 photolysis frequencies in street canyons

    NASA Astrophysics Data System (ADS)

    Koepke, P.; Garhammer, M.; Hess, M.; Roeth, E.-P.

    2010-08-01

    Photolysis frequencies for NO2 are modeled for the conditions in urban streets, which are taken into account as canyons with variable height and width. The effect of a street canyon is presented with absolute values and as a ratio RJ of the photolysis frequency within the street compared to that with free horizon. This allows further use of the existing photolysis parameterizations. Values are presented for variable solar elevation and azimuth angles, varying atmospheric conditions and different street properties. The NO2 photolysis frequency in a street depends strongly on the relative width of the street and its orientation towards the sun. Averaged over atmospheric conditions and street orientation, the NO2 photolysis frequency is reduced in comparison with the values for free horizon: to less than 20% for narrow skyscraper streets, to about 40% for typical urban streets, and only to about 80% for garden streets. A parameterization with the global solar irradiance is given for the averaged RJ values.

  7. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Rob; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This slide presentation reviews the power frequencies for the doubled fiber laser. It includes information on the 780 nm laser, second harmonic generation in one crystal, cascading crystals, the tenability of laser systems, laser cooling, and directions for future work.

  8. Structural damage detection using frequency response functions 

    E-print Network

    Dincal, Selcuk

    2006-04-12

    This research investigates the performance of an existing structural damage detection method (SDIM) when only experimentally-obtained measurement information can be used to calculate the frequency response functions used ...

  9. Multi-frequency cable vibration experiments

    E-print Network

    Wiggins, Andrew (Andrew Dale)

    2005-01-01

    A series of Multi-Frequency cable vibration experiments at Reynolds number 7600 were carried out at the MIT Tow Tank using the Virtual Cable Towing Apparatus (VCTA). Motions observed in a Direct Numerical Simulation of a ...

  10. Frequency-Dependent Electro-osmosis

    E-print Network

    Reppert, Phillip M.

    2002-01-01

    Electro-osmosis, the movement of a fluid with respect to solid wall when an electric field is applied tangentially to the solid wall, has been studied for many years[superscript 1]. Frequency-dependent electro-osmosis ...

  11. Operating frequencies for educational satellite services

    NASA Technical Reports Server (NTRS)

    Singh, J. P.

    1971-01-01

    The factors affecting the choice of transmission frequencies are identified. These include international radio regulations, natural environment, man-made environment, hardware considerations, and interconnection and spectrum space considerations. An analysis is presented of international radio regulations with emphasis on 1963 EARC and 1971 WARC frequency allocations, powerflux density restrictions, and resolutions concerning introduction of broadcasting-satellite systems. Natural-environmental effects were divided into two categories: (1) those due to transionospheric propagation, and (2) those that can be credited to the earth's atmosphere and its constituents. The frequency dependence of the signal attenuation, signal distortion, and contributions to system noise temperature due to environmental effects are discussed, and comparisons were made for frequencies of interest. Man-made environmental effects were examined in terms of various sharing limitations as well as the indigenous noise contribution to the overall system noise.

  12. Characterization of arcs in frequency domain

    SciTech Connect

    D'Inca, R.; Siegl, G.; Faugel, H.; Braun, F.; Eckert, B.; Bobkov, V.; El Khaldi, M.; Noterdaeme, J.-M.

    2009-11-26

    Arc detection systems are developed for ICRH on ITER to prevent arcs from damaging the RF components. One of the detectors, the Sub-Harmonic Arc Detector (SHAD) is based on the detection of the frequencies emitted in the MHz range by arcs [R1]. To ensure the high level of reliability required for this safety system, it is necessary to demonstrate that these frequencies present a signal with a Signal to Noise Ratio high enough to be detected under the wide range of operational conditions (frequency, power, configuration) and for the different types of arcs that can appear in the feeding lines and on the antennas (vacuum arc, glow discharge, multipactor-induced discharge). For each type of arc, we analyze the evolution of the frequency spectrum relative to the evolution of other electrical parameters (reflected power, voltage)

  13. Trajectory of frequency stability in typical development

    E-print Network

    Frohlich, J; Irimia, A; Jeste, SS

    2015-01-01

    surrogate signals closely matches the frequency of alpha oscillations in the childrensurrogate (artificial) signals. In our cohort of children,children had slower average phase reset rates that simulated in our surrogate

  14. Real-time, high frequency QRS electrocardiograph

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T. (Inventor); DePalma, Jude L. (Inventor); Moradi, Saeed (Inventor)

    2006-01-01

    Real time cardiac electrical data are received from a patient, manipulated to determine various useful aspects of the ECG signal, and displayed in real time in a useful form on a computer screen or monitor. The monitor displays the high frequency data from the QRS complex in units of microvolts, juxtaposed with a display of conventional ECG data in units of millivolts or microvolts. The high frequency data are analyzed for their root mean square (RMS) voltage values and the discrete RMS values and related parameters are displayed in real time. The high frequency data from the QRS complex are analyzed with imbedded algorithms to determine the presence or absence of reduced amplitude zones, referred to herein as RAZs. RAZs are displayed as go, no-go signals on the computer monitor. The RMS and related values of the high frequency components are displayed as time varying signals, and the presence or absence of RAZs may be similarly displayed over time.

  15. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aviation Support Stations § 87.323 Frequencies. ...and 123.500 MHz are available for assignment to aviation support stations used for pilot...

  16. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aviation Support Stations § 87.323 Frequencies. ...and 123.500 MHz are available for assignment to aviation support stations used for pilot...

  17. 47 CFR 87.323 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aviation Support Stations § 87.323 Frequencies. ...and 123.500 MHz are available for assignment to aviation support stations used for pilot...

  18. Tidal frequency estimation for closed basins

    NASA Technical Reports Server (NTRS)

    Eades, J. B., Jr.

    1978-01-01

    A method was developed for determining the fundamental tidal frequencies for closed basins of water, by means of an eigenvalue analysis. The mathematical model employed, was the Laplace tidal equations.

  19. Frequency References for Gravitational Wave Missions

    NASA Technical Reports Server (NTRS)

    Preston, Alix; Thrope, J. I.; Donelan, D.; Miner, L.

    2012-01-01

    The mitigation of laser frequency noise is an important aspect of interferometry for LISA-like missions. One portion of the baseline mitigation strategy in LISA is active stabilization utilizing opto-mechanical frequency references. The LISA optical bench is an attractive place to implement such frequency references due to its environmental stability and its access to primary and redundant laser systems. We have made an initial investigation of frequency references constructed using the techniques developed for the LISA and LISA Pathfinder optical benches. Both a Mach-Zehnder interferometer and triangular Fabry-Perot cavity have been successfully bonded to a Zerodur baseplate using the hydroxide bonding method. We will describe the construction of the bench along with preliminary stability results.

  20. 47 CFR 101.1005 - Frequencies available.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... FIXED MICROWAVE SERVICES Local Multipoint Distribution Service § 101.1005 Frequencies available. (a) The... is shared with private microwave point-to-point systems licensed prior to March 11, 1997, as...

  1. Inverse scattering problems with multi-frequencies

    E-print Network

    Gang Bao

    2015-08-24

    Sep 18, 2015 ... submarine detection), geophysical exploration (e.g., oil and gas exploration), ...... The regularization term filters high frequency oscillations and stabilizes ...... Microscopy and Near-field Optics (London: Imperial College Press).

  2. 47 CFR 87.133 - Frequency stability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...20 Hz. 9 Where specific frequencies are not assigned to radar stations, the bandwidth occupied by the emissions of such...10 Hz. (2) All aircraft stations—20 Hz. (d) For radar transmitters, except non-pulse signal radio...

  3. 47 CFR 87.133 - Frequency stability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...20 Hz. 9 Where specific frequencies are not assigned to radar stations, the bandwidth occupied by the emissions of such...10 Hz. (2) All aircraft stations—20 Hz. (d) For radar transmitters, except non-pulse signal radio...

  4. 47 CFR 101.1005 - Frequencies available.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... FIXED MICROWAVE SERVICES Local Multipoint Distribution Service § 101.1005 Frequencies available. (a) The... is shared with private microwave point-to-point systems licensed prior to March 11, 1997, as...

  5. 47 CFR 101.1005 - Frequencies available.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... FIXED MICROWAVE SERVICES Local Multipoint Distribution Service § 101.1005 Frequencies available. (a) The... is shared with private microwave point-to-point systems licensed prior to March 11, 1997, as...

  6. Frequency requirements for active earth observation sensors

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The foundation and rationale for the selection of microwave frequencies for active remote sensing usage and for subsequent use in determination of sharing criteria and allocation strategies for the WARC-79 are presented.

  7. Optical frequency waveguide and ion transmission system

    NASA Technical Reports Server (NTRS)

    Chiao, R. Y.; Townes, C. H.

    1969-01-01

    Electromagnetically generated, high-dielectric tube forms a waveguide which retains the electromagnetic energy within the beam, the trapped beam establishes an optical frequency waveguide appropriate for its own conduction with minimum diffraction loss.

  8. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...45-11.7 GHz are shared with space stations (space to earth) in the fixed-satellite service. (7) This frequency band is shared with space stations (space to earth) in the earth exploration satellite service. (8) This...

  9. 47 CFR 101.803 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...45-11.7 GHz are shared with space stations (space to earth) in the fixed-satellite service. (7) This frequency band is shared with space stations (space to earth) in the earth exploration satellite service. (8) This...

  10. Digital frequency synthesizer for radar astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, R.; Satorius, E.; Robinett, L.; Olson, E.

    1990-01-01

    The digital frequency synthesizer (DFS) is an integral part of the programmable local oscillator (PLO) which is being developed for the NASA's Deep Space Network (DSN) and radar astronomy. Here, the theory of operation and the design of the DFS are discussed, and the design parameters in application for the Goldstone Solar System Radar (GSSR) are specified. The spectral purity of the DFS is evaluated by analytically evaluating the output spectrum of the DFS. A novel architecture is proposed for the design of the DFS with a frequency resolution of 1/2(exp 48) of the clock frequency (0.35 mu Hz at 100 MHz), a phase resolution of 0.0056 degrees (16 bits), and a frequency spur attenuation of -96 dBc.

  11. SRS Process Facility Significance Fire Frequency

    SciTech Connect

    Sarrack, A.G.

    1995-10-01

    This report documents the method and assumptions of a study performed to determine a site generic process facility significant fire initiator frequency and explains the proper way this value should be used.

  12. Radio Frequency Identification : regulating information privacy protection

    E-print Network

    Laufer, Deanna (Deanna Raquel)

    2007-01-01

    As applications of Radio Frequency Identification (RFID) become more profuse, the technology itself is stirring up some controversy. Due to its potential for amassing large amounts of information about both people and ...

  13. 47 CFR 74.762 - Frequency measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.762 Frequency measurements. (a) The licensee of a low power TV station, a...

  14. 47 CFR 74.761 - Frequency tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.761 Frequency tolerance. The licensee of a low power TV, TV...

  15. 47 CFR 74.762 - Frequency measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.762 Frequency measurements. (a) The licensee of a low power TV station, a...

  16. 47 CFR 74.762 - Frequency measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.762 Frequency measurements. (a) The licensee of a low power TV station, a...

  17. 47 CFR 74.761 - Frequency tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.761 Frequency tolerance. The licensee of a low power TV, TV...

  18. 47 CFR 74.761 - Frequency tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.761 Frequency tolerance. The licensee of a low power TV, TV...

  19. 47 CFR 74.762 - Frequency measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.762 Frequency measurements. (a) The licensee of a low power TV station, a...

  20. 47 CFR 74.761 - Frequency tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.761 Frequency tolerance. The licensee of a low power TV, TV...

  1. 47 CFR 74.761 - Frequency tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.761 Frequency tolerance. The licensee of a low power TV, TV...

  2. 47 CFR 74.762 - Frequency measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.762 Frequency measurements. (a) The licensee of a low power TV station, a...

  3. 47 CFR 74.402 - Frequency assignment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup Broadcast Stations § 74... assigned by its center frequency, channel bandwidth, and emission designator. In general, the...

  4. 47 CFR 74.402 - Frequency assignment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup Broadcast Stations § 74... assigned by its center frequency, channel bandwidth, and emission designator. In general, the...

  5. 47 CFR 74.402 - Frequency assignment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup Broadcast Stations § 74... assigned by its center frequency, channel bandwidth, and emission designator. In general, the...

  6. 47 CFR 74.402 - Frequency assignment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup Broadcast Stations § 74... assigned by its center frequency, channel bandwidth, and emission designator. In general, the...

  7. 47 CFR 74.402 - Frequency assignment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup Broadcast Stations § 74... assigned by its center frequency, channel bandwidth, and emission designator. In general, the...

  8. Casimir energy of frequency dependent interactions

    NASA Astrophysics Data System (ADS)

    Graham, N.; Quandt, M.; Weigel, H.

    2014-10-01

    Vacuum polarization (or Casimir) energies can be straightforwardly computed from scattering data for static field configurations whose interactions with the fluctuating field are frequency independent. In effective theories, however, such interactions are typically frequency dependent. As a consequence, the relationship between scattering data and the Green's function is modified, which may or may not induce additional contributions to the vacuum polarization energy. We discuss several examples that naturally include frequency dependent interactions: (i) scalar electrodynamics with a static background potential, (ii) an effective theory that emerges from integrating out a heavy degree of freedom, and (iii) quantum electrodynamics coupled to a frequency dependent dielectric material. In the latter case, we argue that introducing dissipation as required by the Kramers-Kronig relations requires the consideration of the Casimir energy within a statistical mechanics formalism, while in the absence of dissipation, we can work entirely within field theory, using an alternative formulation of the energy density.

  9. 23 CFR 650.311 - Inspection frequency.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...twenty-four months. (2) Certain bridges require inspection at less...and frequency to which these bridges are inspected considering...deficiencies. (3) Certain bridges may be inspected at greater...such factors as construction material, environment, age,...

  10. Overview of the Advanced High Frequency Branch

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2015-01-01

    This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch.

  11. Frequency-agile dual-comb spectroscopy

    E-print Network

    Millot, Guy; Yan, Ming; Hovannysyan, Tatevik; Bendahmane, Abdelkrim; Hänsch, Theodor W; Picqué, Nathalie

    2015-01-01

    We propose a new approach to near-infrared molecular spectroscopy, harnessing advanced concepts of optical telecommunications and supercontinuum photonics. We generate, without mode-locked lasers, two frequency combs of slightly different repetition frequencies and moderate, but rapidly tunable, spectral span. The output of a frequency-agile continuous wave laser is split and sent into two electro-optic intensity modulators. Flat-top low-noise frequency combs are produced by wave-breaking in a nonlinear optical fiber of normal dispersion. With a dual-comb spectrometer, we record Doppler-limited spectra spanning 60 GHz within 13 microseconds and 80-kHz refresh rate, at a tuning speed of 10 nm.s^(-1). The sensitivity for weak absorption is enhanced by a long gas-filled hollow-core fiber.

  12. Radio frequency dc-dc power conversion

    E-print Network

    Rivas, Juan, 1976-

    2007-01-01

    THIS THESIS addresses the development of system architectures and circuit topologies for dc-dc power conversion at very high frequencies. The systems architectures that are developed are structured to overcome limitations ...

  13. Polarization-Frequency Entangled Narrowband Photon Pairs

    NASA Astrophysics Data System (ADS)

    Shu, Chi; Guo, Xianxin; Chen, Peng; Loy, M. M. T.; Du, Shengwang; Du Shengwang Team

    2015-05-01

    We demonstrate a robust scheme to produce narrowband biphotons with polarization-frequency-coupled entanglement from spontaneous four-wave mixing (SFWM) in laser cooled atoms with a right-angle geometry. Making use of an acousto-optic modulator and polarization-dependent two-photon interference, we create a coupled hyperentanglement between the polarization and frequency domains from unentangled SFWM photon pairs. We further demonstrate that, making use of the coupling effect, we can transfer the phase of a complex polarizer into the frequency entanglement and create a tunable two-mode frequency entangled Bell state. The work was supported by the Hong Kong RGC (Project No. 16301214). Chi Shu acknowledges support from the Undergraduate Research Opportunities Programat (UROP) at the Hong Kong University of Science and Technology.

  14. Low frequency projectors for sound under water

    NASA Astrophysics Data System (ADS)

    Rijnja, H. A. J.

    1991-01-01

    The detection of submarines by means of passive sonars becomes more difficult as the radiated noise of submarines is gradually decreasing. There is a need for active sonar transducers that produce sound at frequencies below 1000 Hz. Several kinds of low frequency transducers are presented. Commercially available transducers of the following types are discussed: double piston elements, open hollow cylinders, flextensional transducers, bender bar transducers, electrodynamical systems and hydraulically driven vibrators.

  15. Time and frequency technology at NIST

    NASA Technical Reports Server (NTRS)

    Sullivan, D. B.

    1994-01-01

    The state of development of advanced timing systems at NIST is described. The work on cesium and rubidium frequency standards, stored-ion frequency standards, diode lasers used to pump such standards, time transfer, and methods for characterizing clocks, oscillators, and time distribution systems is presented. The emphasis is on NIST-developed technology rather than the general state of the art in this field.

  16. The calculation of molecular Eigen-frequencies

    NASA Technical Reports Server (NTRS)

    Lindemann, F. A.

    1984-01-01

    A method of determining molecular eigen-frequencies based on the function of Einstein expressing the variation of the atomic heat of various elements is proposed. It is shown that the same equation can be utilized to calculate both atomic heat and optically identifiably eigen-frequencies - at least to an order of magnitude - suggesting that in both cases the same oscillating structure is responsible.

  17. Anomalous Crossing Frequency in Odd Proton Nuclei

    E-print Network

    Yang Sun; Shuxian Wen; Da Hsuan Feng

    1994-02-25

    A generic explanation for the recently observed anomalous crossing frequencies in odd proton rare earth nuclei is given. As an example, the proton ${1\\over 2} [541]$ band in $^{175}$Ta is discussed in detail by using the angular momentum projection theory. It is shown that the quadrupole pairing interaction is decisive in delaying the crossing point and the changes in crossing frequency along the isotope chain are due to the different neutron shell fillings.

  18. Radio frequency interference at the geostationary orbit

    NASA Technical Reports Server (NTRS)

    Sue, M. K.

    1981-01-01

    Growing demands on the frequency spectrum have increased the possibility of radio frequency interference (RFI). Various approaches to obtain in orbit RFI data are compared; this comparision indicates that the most practical way to obtain RFI data for a desired orbit (such as a geostationary orbit) is through the extrapolation of in orbit RFI measurements by a low orbit satellite. It is concluded that a coherent RFI program that uses both experimental data and analytical predictions provides accurate RFI data at minimal cost.

  19. Spectroscopy by frequency-entangled photon pairs

    SciTech Connect

    Yabushita, Atsushi; Kobayashi, Takayoshi

    2004-01-01

    Quantum spectroscopy was performed using the frequency-entangled broadband photon pairs generated by spontaneous parametric down-conversion. An absorptive sample was placed in front of the idler photon detector, and the frequency of signal photons was resolved by a diffraction grating. The absorption spectrum of the sample was measured by counting the coincidences, and the result is in agreement with the one measured by a conventional spectrophotometer with a classical light source.

  20. Frequency-feedback cavity enhanced spectrometer

    DOEpatents

    Hovde, David Christian; Gomez, Anthony

    2015-08-18

    A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.