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Sample records for entanglement-preserving frequency conversion

  1. Entanglement preservation by continuous distillation

    SciTech Connect

    Mundarain, D.; Orszag, M.

    2009-05-15

    We study the two-qubit entanglement preservation for a system in the presence of independent thermal baths. We use a combination of filtering operations and distillation protocols as a series of frequent measurements on the system. It is shown that a small fraction of the total amount of available copies of the system preserves or even improves its initial entanglement during the evolution.

  2. Frequency conversion of structured light.

    PubMed

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

    2016-02-15

    Coherent frequency conversion of structured light, i.e. the ability to manipulate the carrier frequency of a wave front without distorting its spatial phase and intensity profile, provides the opportunity for numerous novel applications in photonic technology and fundamental science. In particular, frequency conversion of spatial modes carrying orbital angular momentum can be exploited in sub-wavelength resolution nano-optics and coherent imaging at a wavelength different from that used to illuminate an object. Moreover, coherent frequency conversion will be crucial for interfacing information stored in the high-dimensional spatial structure of single and entangled photons with various constituents of quantum networks. In this work, we demonstrate frequency conversion of structured light from the near infrared (803 nm) to the visible (527 nm). The conversion scheme is based on sum-frequency generation in a periodically poled lithium niobate crystal pumped with a 1540-nm Gaussian beam. We observe frequency-converted fields that exhibit a high degree of similarity with the input field and verify the coherence of the frequency-conversion process via mode projection measurements with a phase mask and a single-mode fiber. Our results demonstrate the suitability of exploiting the technique for applications in quantum information processing and coherent imaging.

  3. Frequency conversion of structured light

    PubMed Central

    Steinlechner, Fabian; Hermosa, Nathaniel; Pruneri, Valerio; Torres, Juan P.

    2016-01-01

    Coherent frequency conversion of structured light, i.e. the ability to manipulate the carrier frequency of a wave front without distorting its spatial phase and intensity profile, provides the opportunity for numerous novel applications in photonic technology and fundamental science. In particular, frequency conversion of spatial modes carrying orbital angular momentum can be exploited in sub-wavelength resolution nano-optics and coherent imaging at a wavelength different from that used to illuminate an object. Moreover, coherent frequency conversion will be crucial for interfacing information stored in the high-dimensional spatial structure of single and entangled photons with various constituents of quantum networks. In this work, we demonstrate frequency conversion of structured light from the near infrared (803 nm) to the visible (527 nm). The conversion scheme is based on sum-frequency generation in a periodically poled lithium niobate crystal pumped with a 1540-nm Gaussian beam. We observe frequency-converted fields that exhibit a high degree of similarity with the input field and verify the coherence of the frequency-conversion process via mode projection measurements with a phase mask and a single-mode fiber. Our results demonstrate the suitability of exploiting the technique for applications in quantum information processing and coherent imaging. PMID:26875448

  4. Frequency conversion of structured light

    NASA Astrophysics Data System (ADS)

    Steinlechner, Fabian; Hermosa, Nathaniel; Pruneri, Valerio; Torres, Juan P.

    2016-02-01

    Coherent frequency conversion of structured light, i.e. the ability to manipulate the carrier frequency of a wave front without distorting its spatial phase and intensity profile, provides the opportunity for numerous novel applications in photonic technology and fundamental science. In particular, frequency conversion of spatial modes carrying orbital angular momentum can be exploited in sub-wavelength resolution nano-optics and coherent imaging at a wavelength different from that used to illuminate an object. Moreover, coherent frequency conversion will be crucial for interfacing information stored in the high-dimensional spatial structure of single and entangled photons with various constituents of quantum networks. In this work, we demonstrate frequency conversion of structured light from the near infrared (803 nm) to the visible (527 nm). The conversion scheme is based on sum-frequency generation in a periodically poled lithium niobate crystal pumped with a 1540-nm Gaussian beam. We observe frequency-converted fields that exhibit a high degree of similarity with the input field and verify the coherence of the frequency-conversion process via mode projection measurements with a phase mask and a single-mode fiber. Our results demonstrate the suitability of exploiting the technique for applications in quantum information processing and coherent imaging.

  5. 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.

  6. Frequency conversion with nonlinear graphene photodetectors.

    PubMed

    Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

    2017-03-23

    Frequency conversion with nonlinear electronic components, a common approach for signal processing required in various communication applications, has found its operation bandwidth bottleneck due to the limited carrier mobility of the traditional materials. Meanwhile, fiber-optics communications are playing a significant role in communication services due to their excellent signal transmission properties. However, the transmitted optical signals had to be converted to electrical signals with photodetectors before frequency conversion was performed through conventional electronic devices, which make this conversion system very complex and costly. Hence, to develop a compact device that can achieve the photodetection and frequency conversion functions simultaneously is critical and significative. Here, we have proposed a novel concept for frequency conversion and demonstrated a nonlinear graphene photodetector based frequency converter that performs frequency conversion from optical signals directly. With this new concept, a frequency doubling signal at 4 GHz was obtained from a 2 GHz intensity-modulated optical signal. Moreover, using a 10 MHz intensity-modulated optical signal and another 3 GHz intensity-modulated optical signal, we show the frequency up-conversion to 3 ± 0.01 GHz. In particular, the frequency down-conversion to 100 MHz was achieved successfully by using a 2 GHz intensity-modulated optical signal and another 2.1 GHz intensity-modulated optical signal. Considering the broadband optical absorption, strong saturable absorption, high carrier mobility, and short photogenerated carrier lifetime of the graphene material, graphene photodetectors have the potential to achieve the frequency conversion of millimeter-wave band, which will open promising prospects in the domain of microwave photonics for next-gen communication systems.

  7. Quantum Frequency Conversion between Infrared and Ultraviolet

    NASA Astrophysics Data System (ADS)

    Rütz, Helge; Luo, Kai-Hong; Suche, Hubertus; Silberhorn, Christine

    2017-02-01

    We report on the implementation of quantum frequency conversion between infrared and ultraviolet (UV) wavelengths by using single-stage up-conversion in a periodically poled potassium-titanyl-phosphate waveguide. Because of the monolithic waveguide design, we manage to transfer a telecommunication-band input photon to the wavelength of the ionic dipole transition of Yb+ at 369.5 nm. The external (internal) conversion efficiency is around 5% (10%). The high-energy pump used in this converter introduces a spontaneous parametric down-conversion process, which is a cause for noise in the UV mode. Using this process, we show that the converter preserves nonclassical correlations in the up-conversion process, rendering this miniaturized interface a source for quantum states of light in the UV.

  8. Thin-thick quadrature frequency conversion

    SciTech Connect

    Eimerl, D.

    1985-02-07

    The quadrature conversion scheme is a method of generating the second harmonic. The scheme, which uses two crystals in series, has several advantages over single-crystal or other two crystal schemes. The most important is that it is capable of high conversion efficiency over a large dynamic range of drive intensity and detuning angle.

  9. Generation of coherent waves by frequency up-conversion and down-conversion of incoherent light

    SciTech Connect

    Piskarskas, A.; Pyragaite, V.; Stabinis, A.

    2010-11-15

    It is revealed that the generation of a coherent wave by frequency conversion of incoherent waves is a characteristic feature of three-wave interaction in a nonlinear medium when angular dispersion of input waves is properly chosen. In this case the combining action of the pairs of spectral components of incoherent waves may result in the cumulative driving of a single plane monochromatic wave in up-conversion and down-conversion processes. As a fundamental result we point out an enhancement of the spectral radiance of the generated wave in comparison with incoherent waves.

  10. Functional possibilities of nonlinear crystals for frequency conversion: uniaxial crystals

    SciTech Connect

    Andreev, Yu M; Arapov, Yu D; Kasyanov, I V; Grechin, S G; Nikolaev, P P

    2016-01-31

    The method and results of the analysis of phase-matching and nonlinear properties for all point groups of symmetry of uniaxial crystals that determine their functional possibilities for solving various problems of nonlinear frequency conversion of laser radiation are presented. (nonlinear optical phenomena)

  11. Adiabatic frequency conversion with a sign flip in the coupling

    NASA Astrophysics Data System (ADS)

    Hristova, H. S.; Rangelov, A. A.; Montemezzani, G.; Vitanov, N. V.

    2016-09-01

    Adiabatic frequency conversion is a method recently developed in nonlinear optics [H. Suchowski, D. Oron, A. Arie, and Y. Silberberg, Phys. Rev. A 78, 063821 (2008), 10.1103/PhysRevA.78.063821], using ideas from the technique of rapid adiabatic passage (RAP) via a level crossing in quantum physics. In this method, the coupling coefficients are constant and the phase mismatch is chirped adiabatically. In this work, we propose another method for adiabatic frequency conversion, in which the phase mismatch is constant and the coupling is a pulse-shaped function with a sign flip (i.e., a phase step of π ) at its maximum. Compared to the RAP method, our technique has comparable efficiency but it is simpler to implement for it only needs two bulk crystals with opposite χ(2 ) nonlinearity. Moreover, because our technique requires constant nonzero frequency mismatch and has zero conversion efficiency on exact frequency matching, it can be used as a frequency filter.

  12. Highly efficient frequency conversion with bandwidth compression of quantum light

    PubMed Central

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

  13. Highly efficient frequency conversion with bandwidth compression of quantum light

    NASA Astrophysics Data System (ADS)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  14. Giant frequency down-conversion of the dancing acoustic bubble

    PubMed Central

    Deymier, P. A.; Keswani, M.; Jenkins, N.; Tang, C.; Runge, K.

    2016-01-01

    We have demonstrated experimentally the existence of a giant frequency down-conversion of the translational oscillatory motion of individual submillimeter acoustic bubbles in water in the presence of a high frequency (500 kHz) ultrasonic standing wave. The frequency of the translational oscillations (~170 Hz) is more than three orders of magnitude smaller than that of the driving acoustic wave. We elucidate the mechanism of this very slow oscillation with an analytical model leading to an equation of translational motion of a bubble taking the form of Mathieu’s equation. This equation illuminates the origin of the giant down conversion in frequency as arising from an unstable equilibrium. We also show that bubbles that form chains along the direction of the acoustic standing wave due to radiation interaction forces exhibit also translation oscillations that form a spectral band. This band extends approximately from 130 Hz up to nearly 370 Hz, a frequency range that is still at least three orders of magnitude lower than the frequency of the driving acoustic wave. PMID:27857217

  15. Giant frequency down-conversion of the dancing acoustic bubble

    NASA Astrophysics Data System (ADS)

    Deymier, P. A.; Keswani, M.; Jenkins, N.; Tang, C.; Runge, K.

    2016-11-01

    We have demonstrated experimentally the existence of a giant frequency down-conversion of the translational oscillatory motion of individual submillimeter acoustic bubbles in water in the presence of a high frequency (500 kHz) ultrasonic standing wave. The frequency of the translational oscillations (~170 Hz) is more than three orders of magnitude smaller than that of the driving acoustic wave. We elucidate the mechanism of this very slow oscillation with an analytical model leading to an equation of translational motion of a bubble taking the form of Mathieu’s equation. This equation illuminates the origin of the giant down conversion in frequency as arising from an unstable equilibrium. We also show that bubbles that form chains along the direction of the acoustic standing wave due to radiation interaction forces exhibit also translation oscillations that form a spectral band. This band extends approximately from 130 Hz up to nearly 370 Hz, a frequency range that is still at least three orders of magnitude lower than the frequency of the driving acoustic wave.

  16. High efficiency in mode-selective frequency conversion.

    PubMed

    Quesada, Nicolás; Sipe, J E

    2016-01-15

    Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this Letter, we argue that these limits can be understood as time-ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore, using a simple scaling argument, we show that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as "attenuators" of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric downconversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode-selective FC.

  17. Wavelength conversion of incoherent light by sum-frequency generation.

    PubMed

    Arahira, Shin; Murai, Hitoshi

    2014-06-02

    In this paper, we reveal that some kinds of optical nonlinearities are further enhanced when incoherent light, instead of a laser, is used as a pump light. This idea was confirmed both theoretically and experimentally in the case of sum-frequency generation (SFG) using the optical second nonlinearity. The conversion efficiency of the SFG with incoherent light pumping increased as the bandwidth of the incoherent pump light decreased, finally reaching twice the conversion efficiency of conventional second harmonic generation (SHG) by laser pumping. This method dramatically relaxes the severe requirements of phase matching in the nonlinear optical process. The conversion efficiency became less sensitive to misalignment of the wavelength of pump light and also of device operation temperature when the bandwidth of the incoherent pump light was sufficiently broad, although the improvement of the conversion efficiency had an inverse relationship with the insensitivity to the phase-matching condition. The temperature tuning range was enhanced by more than two orders of magnitude in comparison with the conventional SHG method. As an example of a promising application of this new idea, we performed the generation of quantum entangled photon-pairs using cascaded optical nonlinearities (SFG and the subsequent spontaneous parametric down conversion) in a single periodically poled LiNbO3 waveguide device, in which the incoherent light was used as the pump source for both the parametric processes. We have achieved high fidelity exceeding 99% in quantum-state tomography experiments.

  18. Frequency conversion of high-intensity, femtosecond laser pulses

    SciTech Connect

    Banks, P S

    1997-06-01

    Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

  19. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; DePoy, David Moore; Baldasaro, Paul Francis

    2007-01-23

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  20. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; Baldasaro, Paul F.; DePoy, David M.

    2010-09-07

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  1. Quantum frequency up-conversion of continuous variable entangled states

    SciTech Connect

    Liu, Wenyuan; Wang, Ning; Li, Zongyang; Li, Yongmin

    2015-12-07

    We demonstrate experimentally quantum frequency up-conversion of a continuous variable entangled optical field via sum-frequency-generation process. The two-color entangled state initially entangled at 806 and 1518 nm with an amplitude quadrature difference squeezing of 3.2 dB and phase quadrature sum squeezing of 3.1 dB is converted to a new entangled state at 530 and 1518 nm with the amplitude quadrature difference squeezing of 1.7 dB and phase quadrature sum squeezing of 1.8 dB. Our implementation enables the observation of entanglement between two light fields spanning approximately 1.5 octaves in optical frequency. The presented scheme is robust to the excess amplitude and phase noises of the pump field, making it a practical building block for quantum information processing and communication networks.

  2. Quantum frequency up-conversion of continuous variable entangled states

    NASA Astrophysics Data System (ADS)

    Liu, Wenyuan; Wang, Ning; Li, Zongyang; Li, Yongmin

    2015-12-01

    We demonstrate experimentally quantum frequency up-conversion of a continuous variable entangled optical field via sum-frequency-generation process. The two-color entangled state initially entangled at 806 and 1518 nm with an amplitude quadrature difference squeezing of 3.2 dB and phase quadrature sum squeezing of 3.1 dB is converted to a new entangled state at 530 and 1518 nm with the amplitude quadrature difference squeezing of 1.7 dB and phase quadrature sum squeezing of 1.8 dB. Our implementation enables the observation of entanglement between two light fields spanning approximately 1.5 octaves in optical frequency. The presented scheme is robust to the excess amplitude and phase noises of the pump field, making it a practical building block for quantum information processing and communication networks.

  3. Multicomponent cnoidal waves in cascade parametric frequency conversion

    SciTech Connect

    Petnikova, V M; Shuvalov, Vladimir V

    2008-12-31

    It is shown that four-mode interaction in quasi-synchronous cascade frequency conversion on a quadratic nonlinearity can be described in terms of an effective cubic nonlinearity, which reduces the problem to solving the system of two coupled nonlinear Schroedinger equations (NSEs) with respect to the amplitudes of waves involved in both nonlinear processes. Analytic solutions of a new type found for this system have the form of cnoidal waves with components representing the sum and difference of the identical fundamental solutions of the NSE with shifted arguments. The obtained solutions cover the entire range of variation of boundary conditions, allowing the optimisation of the conversion efficiency in any particular situation. (nonlinear optical phenomena)

  4. Modeling beam propagation and frequency conversion for the beamlet laser

    SciTech Connect

    Auerbach, J.M.

    1996-06-01

    The development of the Beamlet laser has involved extensive and detailed modeling of laser performance and beam propagation to: (1) predict the performance limits of the laser, (2) select system configurations with higher performance, (3) analyze experiments and provide guidance for subsequent laser shots, and (4) design optical components and establish component manufacturing specifications. In contrast to modeling efforts of previous laser systems such as Nova, those for Beamlet include as much measured optical characterization data as possible. This article concentrates on modeling of beam propagation in the Beamlet laser system, including the frequency converter, and compares modeling predictions with experimental results for several Beamlet shots. It briefly describes the workstation-based propagation and frequency conversion codes used to accomplish modeling of the Beamlet.

  5. A New Vector Frequency Modulation Method for Power Conversion Circuits

    NASA Astrophysics Data System (ADS)

    Takano, Akio

    This paper presents an excellent PWM method for power conversion circuits. The proposed method is called a Vector Frequency Modulation (VFM) in this paper. VFM does not belong to any conventional PWM methods. Although an idea of space voltage vector is employed in VFM, any traditional equations to calculate the periods of the voltage vectors are not used. The voltage vectors are classified into two groups, zero vectors and non-zero ones. Instead of the complicated equations, a very simple algorithm is employed in VFM. One vector period is fixed and the zero vectors are distributed among the non-zero vectors in the ratio determined by the command voltage or frequency. The behavior of VFM is performed in software and any modulation-wave oscillators, comparators and up-down counters are not needed. At first, a reversible chopper is modulated by VFM and a 2kW DC motor is driven by the chopper. The motor speed is regulated by modern control theory. Next, a three-phase inverter is modulated by VFM and a 2.2kW induction motor is driven by the inverter. Experimental results are shown to prove that VFM is actually useful for power conversion circuits.

  6. WGM Resonators for Terahertz-to-Optical Frequency Conversion

    NASA Technical Reports Server (NTRS)

    Strekalov,Dmitry; Savchenkov, Anatoliy; Matsko, Andrey; Nu, Nan

    2008-01-01

    Progress has been made toward solving some practical problems in the implementation of terahertz-to-optical frequency converters utilizing whispering-gallery-mode (WGM) resonators. Such frequency converters are expected to be essential parts of non-cryogenic terahertz- radiation receivers that are, variously, under development or contemplated for a variety of applications in airborne and spaceborne instrumentation for astronomical and military uses. In most respects, the basic principles of terahertz-to-optical frequency conversion in WGM resonators are the same as those of microwave (sub-terahertz)-to-optical frequency conversion in WGM resonators, various aspects of which were discussed in the three preceeding articles. To recapitulate: In a receiver following this approach, a preamplified incoming microwave signal (in the present case, a terahertz signal) is up-converted to an optical signal by a technique that exploits the nonlinearity of the electromagnetic response of a whispering-gallery-mode (WGM) resonator made of LiNbO3 or another suitable electro-optical material. Upconversion takes place by three-wave mixing in the resonator. To ensure the required interaction among the optical and terahertz signals, the WGM resonator must be designed and fabricated to function as an electro-optical modulator while simultaneously exhibiting (1) resonance at the required microwave and optical operating frequencies and (2) phase matching among the microwave and optical signals circulating in the resonator. Downstream of the WGM resonator, the up-converted signal is processed photonically by use of a tunable optical filter or local oscillator and is then detected. The practical problems addressed in the present development effort are the following: Satisfaction of the optical and terahertz resonance-frequency requirement is a straightforward matter, inasmuch as the optical and terahertz spectra can be measured. However, satisfaction of the phase-matching requirement is

  7. Effective Atom-Molecule Conversions Using Radio Frequency Fields.

    PubMed

    Ding, Yijue; Pérez-Ríos, Jesús; Greene, Chris H

    2016-11-18

    The present study is inspired by the Wieman group experiment [Phys. Rev. Lett. 2005, 95, 190404], in which they use a slow modulated magnetic field to effectively transfer rubidium atoms into cold molecules near a Feshbach resonance. We develop a time-dependent collision theory based on two channel model potentials to study the atom-molecule population transfer induced by a single-color radio frequency field in an ultracold (87) Rb gas. Wave-packet dynamical simulations allow an investigation of both bound-bound transitions and free-bound transitions. The effects of temperature, detuning and the RF amplitude on the population transfer are discussed in detail. Some of our simulations suggest that oscillatory atom-molecule conversion could originate from the long coherence time of the wave packet. This coherence time is unusually long in ultracold gases because the collision energy is typically quite well-defined.

  8. Frequency Up-Conversion Photon-Type Terahertz Imager

    NASA Astrophysics Data System (ADS)

    Fu, Z. L.; Gu, L. L.; Guo, X. G.; Tan, Z. Y.; Wan, W. J.; Zhou, T.; Shao, D. X.; Zhang, R.; Cao, J. C.

    2016-05-01

    Terahertz imaging has many important potential applications. Due to the failure of Si readout integrated circuits (ROICs) and the thermal mismatch between the photo-detector arrays and the ROICs at temperatures below 40 K, there are big technical challenges to construct terahertz photo-type focal plane arrays. In this work, we report pixel-less photo-type terahertz imagers based on the frequency up-conversion technique. The devices are composed of terahertz quantum-well photo-detectors (QWPs) and near-infrared (NIR) light emitting diodes (LEDs) which are grown in sequence on the same substrates using molecular beam epitaxy. In such an integrated QWP-LED device, photocurrent in the QWP drives the LED to emit NIR light. By optimizing the structural parameters of the QWP-LED, the QWP part and the LED part both work well. The maximum values of the internal and external energy up-conversion efficiencies are around 20% and 0.5%. A laser spot of a homemade terahertz quantum cascade laser is imaged by the QWP-LED together with a commercial Si camera. The pixel-less imaging results show that the image blurring induced by the transverse spreading of photocurrent is negligible. The demonstrated pixel-less imaging opens a new way to realize high performance terahertz imaging devices.

  9. Frequency Up-Conversion Photon-Type Terahertz Imager

    PubMed Central

    Fu, Z. L.; Gu, L. L.; Guo, X. G.; Tan, Z. Y.; Wan, W. J.; Zhou, T.; Shao, D. X.; Zhang, R.; Cao, J. C.

    2016-01-01

    Terahertz imaging has many important potential applications. Due to the failure of Si readout integrated circuits (ROICs) and the thermal mismatch between the photo-detector arrays and the ROICs at temperatures below 40 K, there are big technical challenges to construct terahertz photo-type focal plane arrays. In this work, we report pixel-less photo-type terahertz imagers based on the frequency up-conversion technique. The devices are composed of terahertz quantum-well photo-detectors (QWPs) and near-infrared (NIR) light emitting diodes (LEDs) which are grown in sequence on the same substrates using molecular beam epitaxy. In such an integrated QWP-LED device, photocurrent in the QWP drives the LED to emit NIR light. By optimizing the structural parameters of the QWP-LED, the QWP part and the LED part both work well. The maximum values of the internal and external energy up-conversion efficiencies are around 20% and 0.5%. A laser spot of a homemade terahertz quantum cascade laser is imaged by the QWP-LED together with a commercial Si camera. The pixel-less imaging results show that the image blurring induced by the transverse spreading of photocurrent is negligible. The demonstrated pixel-less imaging opens a new way to realize high performance terahertz imaging devices. PMID:27147281

  10. Optical frequency comb based multi-band microwave frequency conversion for satellite applications.

    PubMed

    Yang, Xinwu; Xu, Kun; Yin, Jie; Dai, Yitang; Yin, Feifei; Li, Jianqiang; Lu, Hua; Liu, Tao; Ji, Yuefeng

    2014-01-13

    Based on optical frequency combs (OFC), we propose an efficient and flexible multi-band frequency conversion scheme for satellite repeater applications. The underlying principle is to mix dual coherent OFCs with one of which carrying the input signal. By optically channelizing the mixed OFCs, the converted signal in different bands can be obtained in different channels. Alternatively, the scheme can be configured to generate multi-band local oscillators (LO) for widely distribution. Moreover, the scheme realizes simultaneous inter- and intra-band frequency conversion just in a single structure and needs only three frequency-fixed microwave sources. We carry out a proof of concept experiment in which multiple LOs with 2 GHz, 10 GHz, 18 GHz, and 26 GHz are generated. A C-band signal of 6.1 GHz input to the proposed scheme is successfully converted to 4.1 GHz (C band), 3.9 GHz (C band) and 11.9 GHz (X band), etc. Compared with the back-to-back (B2B) case measured at 0 dBm input power, the proposed scheme shows a 9.3% error vector magnitude (EVM) degradation at each output channel. Furthermore, all channels satisfy the EVM limit in a very wide input power range.

  11. CHRONICLE: Conference on Nonlinear Resonant Conversion of Laser Radiation Frequency, Tashkent, October 3-5, 1979

    NASA Astrophysics Data System (ADS)

    Bakhramov, S. A.; Tartakovskiĭ, G. Kh

    1981-03-01

    A brief review is given of the papers presented at a conference on nonlinear resonant frequency conversion. Attention is concentrated on the following four topics: optically pumped lasers, nonlinear resonant frequency conversion, Raman converters, and physical processes in nonlinear resonant interactions.

  12. ARTICLES: Some features of parametric conversion of infrared radiation in a system generating a difference frequency

    NASA Astrophysics Data System (ADS)

    Galaĭchuk, Yu A.; Strizhevskiĭ, V. L.; Yashkir, Yu N.

    1984-11-01

    A fluctuation theory is developed for the parametric conversion of infrared radiation utilizing four-photon difference frequency generation processes. An analysis is made of some features of optical parametric oscillation in this system allowing for sum frequency generation. Parametric "conversion" of quantum fluctuations to the frequency range of the infrared signal is discussed and it is shown that this effect increases the noise level.

  13. Negative Differential Resistance (NDR) frequency conversion with gain

    NASA Technical Reports Server (NTRS)

    Hwu, R. J.; Alm, R. W.; Lee, S. C.

    1992-01-01

    The dependence of the I-V characteristic of the negative differential resistance (NDR) devices on the power level and frequency of the rf input signal has been theoretically analyzed with a modified large- and small-signal nonlinear circuit analysis program. The NDR devices we used in this work include both the tunnel diode (without the antisymmetry in the I-V characteristic) and resonant-tunneling devices (with the antisymmetry in the I-V characteristic). Absolute negative conductance can be found from a zero-biased resonant tunneling device when the applied pump power is within a small range. This study verifies the work of Sollner et al. Variable negative conductances at the fundamental and harmonic frequencies can also be obtained from both the unbiased and biased tunnel diodes. The magnitude of the negative conductances can be adjusted by varying the pump amplitude -- a very useful circuit property. However, the voltage range over which the negative conductance occurs moves towards the more positive side of the voltage axis with increasing frequency. Furthermore, the range of the pumping amplitude to obtain negative conductance varies with the parasitics (resistance and capacitance) of the device. The theoretical observation of the dependence of the I-V characteristic of the NDR devices on the power and frequency of the applied pump signal is supported by the experimental results. In addition, novel functions of a NDR device such as self-oscillating frequency multiplier and mixer with gain have been experimentally demonstrated. The unbiased oscillator have also been successfully realized with a NDR device with an antisymmetrical I-V characteristic. Finally, the applications of these device functions will be discussed.

  14. An estimate of spherical impactor energy transfer for mechanical frequency up-conversion energy harvester

    NASA Astrophysics Data System (ADS)

    Corr, L. R.; Ma, D. T.

    2016-08-01

    Vibration energy harvesters, which use the impact mechanical frequency up-conversion technique, utilize an impactor, which gains kinetic energy from low frequency ambient environmental vibrations, to excite high frequency systems that efficiently convert mechanical energy to electrical energy. To take full advantage of the impact mechanical frequency up-conversion technique, it is prudent to understand the energy transfer from the low frequency excitations, to the impactor, and finally to the high frequency systems. In this work, the energy transfer from a spherical impactor to a multi degree of freedom spring / mass system, due to Hertzian impact, is investigated to gain insight on how best to design impact mechanical frequency up-conversion energy harvesters. Through this academic work, it is shown that the properties of the contact (or impact) area, i.e., radius of curvature and material properties, only play a minor role in energy transfer and that the equivalent mass of the target system (i.e., the spring / mass system) dictates the total amount of energy transferred during the impact. The novel approach of utilizing the well-known Hertzian impact methodology to gain an understanding of impact mechanical frequency up-conversion energy harvesters has made it clear that the impactor and the high frequency energy generating systems must be designed together as one system to ensure maximum energy transfer, leading to efficient ambient vibration energy harvesters.

  15. Dual-frequency feed system for 26-meter antenna conversion

    NASA Technical Reports Server (NTRS)

    Hartop, R. W.

    1977-01-01

    New cassegrain feed cone assemblies were designed as part of the upgrade of three 26-meter diameter antennas to 34-meter diameter with improved performance. The new dual-frequency feed cone (SXD) will provide both S- and X-band feed systems and traveling wave masers, with a reflex reflector system to permit simultaneous operation analogous to the 64-meter antennas. Tasks involved in adding the X-band receiving capability and improving the S-band feed performance in support of Voyager and later missions described in.

  16. Efficient and low-noise single-photon-level frequency conversion interfaces using silicon nanophotonics

    NASA Astrophysics Data System (ADS)

    Li, Qing; Davanço, Marcelo; Srinivasan, Kartik

    2016-06-01

    Optical frequency conversion has applications ranging from tunable light sources to telecommunications-band interfaces for quantum information science. Here, we demonstrate efficient, low-noise frequency conversion on a nanophotonic chip through four-wave-mixing Bragg scattering in compact (footprint <0.5 × 10-4 cm2) Si3N4 microring resonators. We investigate three frequency conversion configurations: spectral translation over a few nanometres within the 980 nm band; upconversion from 1,550 nm to 980 nm and downconversion from 980 nm to 1,550 nm. With conversion efficiencies ranging from 25% for the first process to >60% for the last two processes, a signal conversion bandwidth of >1 GHz, a required continuous-wave pump power of <60 mW and background noise levels between a few femtowatts and a few picowatts, these devices are suitable for quantum frequency conversion of single-photon states from InAs/GaAs quantum dots. Simulations based on coupled mode equations and the Lugiato-Lefever equation are used to model device performance, and show quantitative agreement with measurements.

  17. Nonlinear systems for frequency conversion from IR to RF

    NASA Astrophysics Data System (ADS)

    Dolasinski, Brian D.

    The objective of this dissertation is to evaluate and develop novel sources for tunable narrowband IR generation, tunable narrowband THz generation, and ultra-wideband RF generation to be used in possible non-destructive evaluation systems. Initially a periodically poled Lithium Niobate (PPLN) based optical parametric amplifier (OPA) is designed using a double-pass configuration where a small part of the pump is used on the first pass to generate a signal, which is reflected and filtered by an off-axis etalon. The portion of the pump that is not phase matched on the first pass is retro-reflected back into the PPLN crystal and is co-aligned with the narrow bandwidth filtered signal and amplified. We demonstrate that the system is tunable in the 1.4 microm -1.6 microm signal range with a linewidth of 5.4 GHz. Next the outputs of seeded, dual periodically poled lithium niobate (PPLN) optical parametric amplifiers (OPA) are combined in the nonlinear crystal 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) to produce a widely tunable narrowband THz source via difference frequency generation (DFG). We have demonstrated that this novel configuration enables the system to be seamlessly tuned, without mode-hops, from 1.2 THz to 26.3 THz with a minimum bandwidth of 3.1 GHz. The bandwidth of the source was measured by using the THz transmission spectrum of water vapor lines over a 3-meter path length. By selecting of the DFG pump wavelength to be at 1380 nm and the signal wavelength to tune over a range from 1380 nm to 1570 nm, we produced several maxima in the output THz spectrum that was dependent on the phase matching ability of the DAST crystal and the efficiency of our pyro-electric detector. Due to the effects of dispersive phase matching, filter absorption of the THz waves, and two-photon absorption multiple band gaps in the overall spectrum occur and are discussed. Employing the dual generator scheme, we have obtained THz images at several locations in the

  18. Efficient second-harmonic conversion of CW single-frequency Nd:YAG laser light by frequency locking to a monolithic ring frequency doubler

    NASA Technical Reports Server (NTRS)

    Gerstenberger, D. C.; Tye, G. E.; Wallace, R. W.

    1991-01-01

    Efficient second-harmonic conversion of the 1064-nm output of a diode-pumped CW single-frequency Nd:YAG laser to 532 nm was obtained by frequency locking the laser to a monolithic ring resonator constructed of magnesium-oxide-doped lithium niobate. The conversion efficiency from the fundamental to the second harmonic was 65 percent. Two hundred milliwatts of CW single-frequency 532-nm light were produced from 310 mW of power of 1064-nm light. This represents a conversion efficiency of 20 percent from the 1-W diode laser used to pump the Nd:YAG laser to single-frequency 532-nm output. No signs of degradation were observed for over 500 h of operation.

  19. Ultra-broadband microwave frequency down-conversion based on optical frequency comb.

    PubMed

    Fang, Xiao; Bai, Ming; Ye, Xiuzhu; Miao, Jungang; Zheng, Zheng

    2015-06-29

    Based on optical frequency comb (OFC), a photonic-assisted ultra-broadband microwave signal down-converting method is proposed. In the proposed scheme, microwave signal at 2~20GHz can be down-converted to 0~1GHz intermediate frequency (IF) signals by an OFC of 2GHz frequency space at different order of comb lines. By slightly switching the frequency space of OFC, the frequency of the signal to be measured can be retrieved through the frequency shift of the down-converted IF signal. The validity of this proposed unknown signal detection method is verified by the experiments. The proposed method is proven to be flexible, low-cost and easily implemented, which requires only a low-frequency tunable microwave source while provides ultra-broadband down-converting frequency range.

  20. Entanglement and nonclassicality in four-mode Gaussian states generated via parametric down-conversion and frequency up-conversion

    PubMed Central

    Arkhipov, Ievgen I.; Peřina Jr., Jan; Haderka, Ondřej; Allevi, Alessia; Bondani, Maria

    2016-01-01

    Multipartite entanglement and nonclassicality of four-mode Gaussian states generated in two simultaneous nonlinear processes involving parametric down-conversion and frequency up-conversion are analyzed assuming the vacuum as the initial state. Suitable conditions for the generation of highly entangled states are found. Transfer of the entanglement from the down-converted modes into the up-converted ones is also suggested. The analysis of the whole set of states reveals that sub-shot-noise intensity correlations between the equally-populated down-converted modes, as well as the equally-populated up-converted modes, uniquely identify entangled states. They represent a powerful entanglement identifier also in other cases with arbitrarily populated modes. PMID:27658508

  1. Power conversion distribution system using a resonant high-frequency AC link

    NASA Technical Reports Server (NTRS)

    Sood, P. K.; Lipo, T. A.

    1986-01-01

    Static power conversion systems based on a resonant high frequency (HF) link offers a significant reduction in the size and weight of the equipment over that achieved with conventional approaches, especially when multiple sources and loads are to be integrated. A faster system response and absence of audible noise are the other principal characteristics of such systems. A conversion configuration based on a HF link which is suitable for applications requiring distributed power is proposed.

  2. Design of diamond microcavities for single photon frequency down-conversion.

    PubMed

    Lin, Z; Johnson, S G; Rodriguez, A W; Loncar, M

    2015-09-21

    We propose monolithic diamond cavities that can be used to convert color-center Fock-state single photons from emission wavelengths to telecommunication bands. We present a detailed theoretical description of the conversion process, analyzing important practical concerns such as nonlinear phase shifts and frequency mismatch. Our analysis predicts sustainable power requirements (≲ 1 W) for a chipscale nonlinear device with high conversion efficiencies.

  3. Sub-bandgap transverse frequency conversion in semiconductor nano-waveguides

    NASA Astrophysics Data System (ADS)

    Gu, Fuxing; Zhang, Li; Wu, Guoqing; Zhu, Yingbin; Zeng, Heping

    2014-10-01

    Transverse frequency conversion in the sub-bandgap spectral region is investigated in semiconductor nanowires and nanoribbons using CW lasers with a pump power less than 1 mW. It is found that the properties of the emissions are strongly dependent on the cross-sectional geometries and the surrounding media of nano-waveguides. The polarization is higher in nano-waveguides under single-mode conditions, and the spatial distribution is more tunable in nano-waveguides with higher-order modes involved. Compared with the birefringent approach, transverse frequency conversion shows lower divergence angles, higher polarization, and more tunable spatial distribution.

  4. Sub-bandgap transverse frequency conversion in semiconductor nano-waveguides.

    PubMed

    Gu, Fuxing; Zhang, Li; Wu, Guoqing; Zhu, Yingbin; Zeng, Heping

    2014-11-07

    Transverse frequency conversion in the sub-bandgap spectral region is investigated in semiconductor nanowires and nanoribbons using CW lasers with a pump power less than 1 mW. It is found that the properties of the emissions are strongly dependent on the cross-sectional geometries and the surrounding media of nano-waveguides. The polarization is higher in nano-waveguides under single-mode conditions, and the spatial distribution is more tunable in nano-waveguides with higher-order modes involved. Compared with the birefringent approach, transverse frequency conversion shows lower divergence angles, higher polarization, and more tunable spatial distribution.

  5. Large-alphabet time-frequency entangled quantum key distribution by means of time-to-frequency conversion

    NASA Astrophysics Data System (ADS)

    Nunn, J.; Wright, L. J.; Söller, C.; Zhang, L.; Walmsley, I. A.; Smith, B. J.

    2013-07-01

    We introduce a novel time-frequency quantum key distribution (TFQKD) scheme based on photon pairs entangled in these two conjugate degrees of freedom. The scheme uses spectral detection and phase modulation to enable measurements in the temporal basis by means of time-to-frequency conversion. This allows large-alphabet encoding to be implemented with realistic components. A general security analysis for TFQKD with binned measurements reveals a close connection with finite-dimensional QKD protocols and enables analysis of the effects of dark counts on the secure key size.

  6. A chip-scale, telecommunications-band frequency conversion interface for quantum emitters.

    PubMed

    Agha, Imad; Ates, Serkan; Davanço, Marcelo; Srinivasan, Kartik

    2013-09-09

    We describe a chip-scale, telecommunications-band frequency conversion interface designed for low-noise operation at wavelengths desirable for common single photon emitters. Four-wave-mixing Bragg scattering in silicon nitride waveguides is used to demonstrate frequency upconversion and downconversion between the 980 nm and 1550 nm wavelength regions, with signal-to-background levels > 10 and conversion efficiency of ≈ -60 dB at low continuous wave input pump powers (< 50 mW). Finite element simulations and the split-step Fourier method indicate that increased input powers of ≈ 10 W (produced by amplified nanosecond pulses, for example) will result in a conversion efficiency > 25 % in existing geometries. Finally, we present waveguide designs that can be used to connect shorter wavelength (637 nm to 852 nm) quantum emitters with 1550 nm.

  7. A nonlinear screen as an element for sound absorption and frequency conversion systems

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.

    2016-01-01

    The paper discusses a model for a screen with dissipative and nonlinear elastic properties that can be used in acoustic sound absorption and frequency conversion systems. Calculation and estimation schemes are explained that are necessary for understanding the functional capabilities of the device. Examples of the nonlinear elements in the screen and promising applications are described.

  8. High efficiency in Mode Selective Frequency Conversion for Optical Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Quesada, Nicolas; Sipe, J. E.

    Mode selective Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this contribution we show that these limits can be understood as time ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore we show, using a simple scaling argument, that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as ``attenuators'' of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric down-conversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode selective FC.

  9. Single-photon frequency conversion via interaction with a three-level atom coupled to a microdisk

    NASA Astrophysics Data System (ADS)

    Akbari, M.; Andrianov, S. N.; Kalachev, A. A.

    2017-02-01

    The frequency conversion of light has proved to be an important instrument for communication, spectroscopy, imaging and information processing. We theoretically study the frequency conversion of a single photon via its interaction with a Λ -type atom coupled to a microdisk. We show that the frequency conversion efficiency approaches unity even in the case of an interaction between clockwise and counterclockwise modes in the microdisk due to surface imperfections. By the use of the Schrieffer-Wolff transformation, we get an effective Hamiltonian that allows us to investigate the dynamics of the system and obtain time and probability of frequency conversion in different conditions.

  10. Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory.

    PubMed

    Fisher, Kent A G; England, Duncan G; MacLean, Jean-Philippe W; Bustard, Philip J; Resch, Kevin J; Sussman, Benjamin J

    2016-04-05

    The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion.

  11. Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory

    PubMed Central

    Fisher, Kent A. G.; England, Duncan G.; MacLean, Jean-Philippe W.; Bustard, Philip J.; Resch, Kevin J.; Sussman, Benjamin J.

    2016-01-01

    The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion. PMID:27045988

  12. Freely designable optical frequency conversion in Raman-resonant four-wave-mixing process

    PubMed Central

    Zheng, Jian; Katsuragawa, Masayuki

    2015-01-01

    Nonlinear optical processes are governed by the relative-phase relationships among the relevant electromagnetic fields in these processes. In this Report, we describe the physics of arbitrary manipulation of Raman-resonant four-wave-mixing process by artificial control of relative phases. As a typical example, we show freely designable optical-frequency conversions to extreme spectral regions, mid-infrared and vacuum-ultraviolet, with near-unity quantum efficiencies. Furthermore, we show that such optical-frequency conversions can be realized by using a surprisingly simple technology where transparent plates are placed in a nonlinear optical medium and their positions and thicknesses are adjusted precisely. In a numerical simulation assuming practically applicable parameters in detail, we demonstrate a single-frequency tunable laser that covers the whole vacuum-ultraviolet spectral range of 120 to 200 nm. PMID:25748023

  13. Very-high-frequency dc-to-dc conversion and regulation in the low-megahertz range.

    NASA Technical Reports Server (NTRS)

    Feng, S. Y. M.; Wilson, T. G.; Sander, W. A., III

    1971-01-01

    Anticipated new mission requirements have motivated research on very-high-frequency (VHF) regulated dc-to-dc converters to operate at conversion frequencies in the low-megahertz range. State-of-the-art electronic components for VHF operation are discussed. Two different converter configurations, one using proportional control and having a conversion frequency of 0.1 MHz and the other using bistable control and having a conversion frequency of 3.8 MHz, are presented to indicate converter performance in this VHF region. Converter losses, which are of prime importance at these frequencies, are discussed and possible means of reducing these losses are suggested.

  14. Chromosomal double-strand breaks induce gene conversion at high frequency in mammalian cells.

    PubMed Central

    Taghian, D G; Nickoloff, J A

    1997-01-01

    Double-strand breaks (DSBs) stimulate chromosomal and extrachromosomal recombination and gene targeting. Transcription also stimulates spontaneous recombination by an unknown mechanism. We used Saccharomyces cerevisiae I-SceI to stimulate recombination between neo direct repeats in Chinese hamster ovary (CHO) cell chromosomal DNA. One neo allele was controlled by the dexamethasone-inducible mouse mammary tumor virus promoter and inactivated by an insertion containing an I-SceI site at which DSBs were introduced in vivo. The other neo allele lacked a promoter but carried 12 phenotypically silent single-base mutations that create restriction sites (restriction fragment length polymorphisms). This system allowed us to generate detailed conversion tract spectra for recipient alleles transcribed at high or low levels. Transient in vivo expression of I-SceI increased homologous recombination 2,000- to 10,000-fold, yielding recombinants at frequencies as high as 1%. Strikingly, 97% of these products arose by gene conversion. Most products had short, bidirectional conversion tracts, and in all cases, donor neo alleles (i.e., those not suffering a DSB) remained unchanged, indicating that conversion was fully nonreciprocal. DSBs in exogenous DNA are usually repaired by end joining requiring little or no homology or by nonconservative homologous recombination (single-strand annealing). In contrast, we show that chromosomal DSBs are efficiently repaired via conservative homologous recombination, principally gene conversion without associated crossing over. For DSB-induced events, similar recombination frequencies and conversion tract spectra were found under conditions of low and high transcription. Thus, transcription does not further stimulate DSB-induced recombination, nor does it appear to affect the mechanism(s) by which DSBs induce gene conversion. PMID:9343400

  15. Microwave frequency measurement based on photonic sampling analog-to-digital conversion

    NASA Astrophysics Data System (ADS)

    Ma, Yangxue; Zhang, Zhiyao; Peng, Di; Zou, Jinfang; Liu, Yong

    2016-11-01

    A new microwave photonic approach to microwave frequency measurement with a high resolution and a large bandwidth is proposed. In this method, three photonic sampling analog-to-digital converters (ADCs) with co-prime sampling rates are employed. Three Fourier frequencies acquiring through down-converted analog-to-digital conversion of the unknown microwave signal are utilized to recovery the frequency of the unknown signal. The simulation results show that a microwave frequency measurement system which is feasible for multi-frequency microwave signal achieves a large measurement range of 0-50GHz and an accuracy of+/-1MHz. In addition, the spur-free dynamic range of 101.1dB-Hz2/3@50GHz is also numerically demonstrated.

  16. Multicomponent glass materials with the raised efficiency for conversion of laser radiation frequency

    NASA Astrophysics Data System (ADS)

    Smirnov, V. A.; Vostrikova, L. I.; Schavelev, O. S.; Schavelev, K. O.; Jakobson, N. A.

    2010-02-01

    Nonlinear conversions of laser radiation frequency on the photo-integrated volumetric structures of the second-order susceptibility, created by all-optical poling, have been investigated in various glass mediums. The detailed analysis of the influence of a chemical compound was carried out, and as a result, the perspective multi-lead phosphate glasses with the concentration of the some percents of niobium oxide have been synthesized in which the greatest efficiency of the conversion of light is observed in conditions of long lifetime of the photo-integrated structures. The studied photointegrated structures may be useful in future for the creation of the various photonic devices for micro- and nanoelectronics.

  17. Multicomponent glass materials with the raised efficiency for conversion of laser radiation frequency

    NASA Astrophysics Data System (ADS)

    Smirnov, V. A.; Vostrikova, L. I.; Schavelev, O. S.; Schavelev, K. O.; Jakobson, N. A.

    2009-10-01

    Nonlinear conversions of laser radiation frequency on the photo-integrated volumetric structures of the second-order susceptibility, created by all-optical poling, have been investigated in various glass mediums. The detailed analysis of the influence of a chemical compound was carried out, and as a result, the perspective multi-lead phosphate glasses with the concentration of the some percents of niobium oxide have been synthesized in which the greatest efficiency of the conversion of light is observed in conditions of long lifetime of the photo-integrated structures. The studied photointegrated structures may be useful in future for the creation of the various photonic devices for micro- and nanoelectronics.

  18. Design concepts for stable AR coatings on UV frequency conversion crystals

    NASA Astrophysics Data System (ADS)

    Jensen, Lars; Mrohs, Marius; Günster, Stefan; Ristau, Detlev

    2014-10-01

    In an effort to develop next generation UV frequency conversion systems, several steps have to be considered. One aspect crucial for the final conversion stage is a durable coating which shows high resistance for all incident wavelengths. In the regular case, two wavelengths are involved in the generation of the fourth harmonic of the Nd:YAG laser. For a conversion process involving the wavelengths 532nm and 266nm, model AR-coating designs have been developed and tested including SiO2, Al2O3, and HfO2 deposited in an IBS process. During the testing, procedures have been applied that involve both wavelengths at the same time. As in the application, the exit surface is exposed to visible and UV laser radiation, a qualifying test needs to account for these conditions as well.

  19. Nonlinear frequency conversion in bismuth-doped tellurite suspended core fiber

    NASA Astrophysics Data System (ADS)

    Ryasnyanskiy, Aleksandr; Lin, Aoxiang; Belwalkar, Amit; Guintrand, Cyril; Biaggio, Ivan; Toulouse, Jean

    2011-08-01

    We have developed a new kind of tellurite glass with composition 70.5TeO 2-12ZnO-10Na 2O-7.5Bi 2O 3 by conventional melting-quenching techniques. A suspended-core fiber (SCF) with a triangular-shaped core (~ 2.9 μm) has been drawn from an extruded perform. Several nonlinear frequency conversion processes are being demonstrated, which point to the potential of such a fiber.

  20. Theory of quantum frequency conversion and type-II parametric down-conversion in the high-gain regime

    NASA Astrophysics Data System (ADS)

    Christ, Andreas; Brecht, Benjamin; Mauerer, Wolfgang; Silberhorn, Christine

    2013-05-01

    Frequency conversion (FC) and type-II parametric down-conversion (PDC) processes serve as basic building blocks for the implementation of quantum optical experiments: type-II PDC enables the efficient creation of quantum states such as photon-number states and Einstein-Podolsky-Rosen (EPR)-states. FC gives rise to technologies enabling efficient atom-photon coupling, ultrafast pulse gates and enhanced detection schemes. However, despite their widespread deployment, their theoretical treatment remains challenging. Especially the multi-photon components in the high-gain regime as well as the explicit time-dependence of the involved Hamiltonians hamper an efficient theoretical description of these nonlinear optical processes. In this paper, we investigate these effects and put forward two models that enable a full description of FC and type-II PDC in the high-gain regime. We present a rigorous numerical model relying on the solution of coupled integro-differential equations that covers the complete dynamics of the process. As an alternative, we develop a simplified model that, at the expense of neglecting time-ordering effects, enables an analytical solution. While the simplified model approximates the correct solution with high fidelity in a broad parameter range, sufficient for many experimental situations, such as FC with low efficiency, entangled photon-pair generation and the heralding of single photons from type-II PDC, our investigations reveal that the rigorous model predicts a decreased performance for FC processes in quantum pulse gate applications and an enhanced EPR-state generation rate during type-II PDC, when EPR squeezing values above 12 dB are considered.

  1. Broadband electromagnetic power harvester from vibrations via frequency conversion by impact oscillations

    SciTech Connect

    Yuksek, N. S.; Almasri, M.; Feng, Z. C.

    2014-09-15

    In this paper, we propose an electromagnetic power harvester that uses a transformative multi-impact approach to achieve a wide bandwidth response from low frequency vibration sources through frequency-up conversion. The device consists of a pick-up coil, fixed at the free edge of a cantilever beam with high resonant frequency, and two cantilever beams with low excitation frequencies, each with an impact mass attached at its free edge. One of the two cantilevers is designed to resonate at 25 Hz, while the other resonates at 50 Hz within the range of ambient vibration frequency. When the device is subjected to a low frequency vibration, the two low-frequency cantilevers responded by vibrating at low frequencies, and thus their thick metallic masses made impacts with the high resonance frequency cantilever repeatedly at two locations. This has caused it along with the pick-up coil to oscillate, relative to the permanent magnet, with decaying amplitude at its resonance frequency, and results in a wide bandwidth response from 10 to 63 Hz at 2 g. A wide bandwidth response between 10–51 Hz and 10–58 Hz at acceleration values of 0.5 g and 2 g, respectively, were achieved by adjusting the impact cantilever frequencies closer to each other (25 Hz and 45 Hz). A maximum output power of 85 μW was achieved at 5 g at 30 Hz across a load resistor, 2.68 Ω.

  2. Biased gene conversion skews allele frequencies in human populations, increasing the disease burden of recessive alleles.

    PubMed

    Lachance, Joseph; Tishkoff, Sarah A

    2014-10-02

    Gene conversion results in the nonreciprocal transfer of genetic information between two recombining sequences, and there is evidence that this process is biased toward G and C alleles. However, the strength of GC-biased gene conversion (gBGC) in human populations and its effects on hereditary disease have yet to be assessed on a genomic scale. Using high-coverage whole-genome sequences of African hunter-gatherers, agricultural populations, and primate outgroups, we quantified the effects of GC-biased gene conversion on population genomic data sets. We find that genetic distances (FST and population branch statistics) are modified by gBGC. In addition, the site frequency spectrum is left-shifted when ancestral alleles are favored by gBGC and right-shifted when derived alleles are favored by gBGC. Allele frequency shifts due to gBGC mimic the effects of natural selection. As expected, these effects are strongest in high-recombination regions of the human genome. By comparing the relative rates of fixation of unbiased and biased sites, the strength of gene conversion was estimated to be on the order of Nb ≈ 0.05 to 0.09. We also find that derived alleles favored by gBGC are much more likely to be homozygous than derived alleles at unbiased SNPs (+42.2% to 62.8%). This results in a curse of the converted, whereby gBGC causes substantial increases in hereditary disease risks. Taken together, our findings reveal that GC-biased gene conversion has important population genetic and public health implications.

  3. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    SciTech Connect

    Sun, Kyung Ho; Kim, Young-Cheol; Kim, Jae Eun

    2014-10-15

    While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.

  4. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    NASA Astrophysics Data System (ADS)

    Sun, Kyung Ho; Kim, Young-Cheol; Kim, Jae Eun

    2014-10-01

    While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.

  5. Bi-directional conversion between microwave and optical frequencies in a piezoelectric optomechanical device

    NASA Astrophysics Data System (ADS)

    Vainsencher, Amit; Satzinger, K. J.; Peairs, G. A.; Cleland, A. N.

    2016-07-01

    We describe the principles of design, fabrication, and operation of a piezoelectric optomechanical crystal with which we demonstrate bi-directional conversion of energy between microwave and optical frequencies. The optomechanical crystal has an optical mode at 1523 nm co-located with a mechanical breathing mode at 3.8 GHz, with a measured optomechanical coupling strength gom/2π of 115 kHz. The breathing mode is driven and detected by curved interdigitated transducers that couple to a Lamb mode in suspended membranes on either end of the optomechanical crystal, allowing the external piezoelectric modulation of the optical signal as well as the converse, the detection of microwave electrical signals generated by a modulated optical signal. We compare measurements to theory where appropriate.

  6. Nonlinear frequency conversion effect in a one-dimensional graphene-based photonic crystal

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2015-07-01

    In this research, the nonlinear frequency conversion effect based on four-wave mixing (FWM) principle in a onedimensional graphene-based photonics crystal (1D-GPC) has been investigated numerically. The 1D-GPC structure is composed of two periodically alternating material layers, which are graphene-silicon dioxide bilayer system and silicon membrane. Since, the third-order nonlinear susceptibility χ(3) of bilayer system is hundred time higher than pure silicon dioxide layer, so the enhancement of FWM response can be achieved inside the structure with optimizing photon energy being much higher than a chemical potential level (μ) of graphene sheet. In addition, the conversion efficiencies of 1DGPC structure are compared with chalcogenide based photonic structure for showing that 1D-GPC structure can enhance nonlinear effect by a factor of 100 above the chalcogenide based structure with the same structure length.

  7. Properties and Frequency Conversion of High-Brightness Diode-Laser Systems

    NASA Astrophysics Data System (ADS)

    Boller, Klaus-Jochen; Beier, Bernard; Wallenstein, Richard

    An overview of recent developments in the field of high-power, high-brightness diode-lasers, and the optically nonlinear conversion of their output into other wavelength ranges, is given. We describe the generation of continuous-wave (CW) laser beams at power levels of several hundreds of milliwatts to several watts with near-perfect spatial and spectral properties using Master-Oscillator Power-Amplifier (MOPA) systems. With single- or double-stage systems, using amplifiers of tapered or rectangular geometry, up to 2.85 W high-brightness radiation is generated at wavelengths around 810nm with AlGaAs diodes. Even higher powers, up to 5.2W of single-frequency and high spatial quality beams at 925nm, are obtained with InGaAs diodes. We describe the basic properties of the oscillators and amplifiers used. A strict proof-of-quality for the diode radiation is provided by direct and efficient nonlinear optical conversion of the diode MOPA output into other wavelength ranges. We review recent experiments with the highest power levels obtained so far by direct frequency doubling of diode radiation. In these experiments, 100mW single-frequency ultraviolet light at 403nm was generated, as well as 1W of single-frequency blue radiation at 465nm. Nonlinear conversion of diode radiation into widely tunable infrared radiation has recently yielded record values. We review the efficient generation of widely tunable single-frequency radiation in the infrared with diode-pumped Optical Parametric Oscillators (OPOs). With this system, single-frequency output radiation with powers of more than 0.5W was generated, widely tunable around wavelengths of 2.1,m and 1.65,m and with excellent spectral and spatial quality. These developments are clear indicators of recent advances in the field of high-brightness diode-MOPA systems, and may emphasize their future central importance for applications within a vast range of optical

  8. Phase-matching conditions for nonlinear frequency conversion by use of aligned molecular gases.

    PubMed

    Bartels, R A; Wagner, N L; Baertschy, M D; Wyss, J; Murnane, M M; Kapteyn, H C

    2003-03-01

    Transient birefringence can be induced in a gas of anisotropic molecules by an intense polarized laser pulse. We propose to use this birefringence to phase match nonlinear optical frequency-conversion processes. The conditions for anisotropic phase matching are derived, and experimental conditions required for phase-matched third-harmonic generation in a gas-filled hollow-core fiber are presented. We show that these conditions are experimentally feasible over a significant parameter range, making possible a new type of nonlinear optics.

  9. Strong Field-Induced Frequency Conversion of Laser Radiation in Plasma Plumes: Recent Achievements

    PubMed Central

    Ganeev, R. A.

    2013-01-01

    New findings in plasma harmonics studies using strong laser fields are reviewed. We discuss recent achievements in the growth of the efficiency of coherent extreme ultraviolet (XUV) radiation sources based on frequency conversion of the ultrashort pulses in the laser-produced plasmas, which allowed for the spectral and structural studies of matter through the high-order harmonic generation (HHG) spectroscopy. These studies showed that plasma HHG can open new opportunities in many unexpected areas of laser-matter interaction. Besides being considered as an alternative method for generation of coherent XUV radiation, it can be used as a powerful tool for various spectroscopic and analytical applications. PMID:23864818

  10. Low-noise quantum frequency down-conversion of indistinguishable photons (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kambs, Benjamin; Kettler, Jan; Bock, Matthias; Becker, Jonas; Arend, Carsten; Jetter, Michael; Michler, Peter; Becher, Christoph

    2016-04-01

    Single-photon sources based on quantum dots have been shown to exhibit almost ideal properties such as high brightness and purity in terms of clear anti-bunching as well as high two-photon interference visibilities of the emitted photons, making them promising candidates for different quantum information applications such as quantum computing, quantum communication and quantum teleportation. However, as most single-photon sources also quantum dots typically emit light at wavelengths of electronic transitions within the visible or the near infrared range. In order to establish quantum networks with remote building blocks, low-loss single photons at telecom wavelengths are preferable, though. Despite recent progress on emitters of telecom-photons, the most efficient single-photon sources still work at shorter wavelengths. On that matter, quantum frequency down-conversion, being a nonlinear optical process, has been used in recent years to alter the wavelength of single photons to the telecom wavelength range while conserving their nonclassical properties. Characteristics such as lifetime, first-order coherence, anti-bunching and entanglement have been shown to be conserved or even improved due to background suppression during the conversion process, while the conservation of indistinguishability was yet to be shown. Here we present our experimental results on quantum frequency down-conversion of single photons emitted by an InAs/GaAs quantum dot at 903.6 nm following a pulsed excitation of a p-shell exciton at 884 nm. The emitted fluorescence photons are mixed with a strong pump-field at 2155 nm inside a periodically poled lithium niobate ridge waveguide and converted to 1557 nm. Common issues of a large background due to Raman-scattered pump-light photons spectrally overlapping with the converted single photons could largely be avoided, as the pump-wavelength was chosen to be fairly longer than the target wavelength. Additional narrowband spectral filtering at the

  11. Comment on "Mode Conversion of Waves In The Ion-Cyclotron Frequency Range in Magnetospheric Plasmas"

    SciTech Connect

    Kim, Eun; Johnson, J. R.

    2014-02-01

    Recently, Kazakov and Fulop [1] studied mode conversion (MC) at the ion-ion hybrid (IIH) resonance in planetary magnetospheric plasmas by simplifying the dispersion relation of the fast wave (FW) modes to describe a cutoff-resonance (CR) pair near the IIH resonance, which can be reduced to a Budden problem. They suggested that when the IIH resonance frequency (ωS) approaches the crossover frequency (ωcr), and the parallel wavenumber (k∥) is close to the critical wavenumber k* ∥(ωS = ωcr), MC can be efficient for arbitrary heavy ion density ratios. In this Comment, we argue that (a) the FW dispersion relation cannot be simplified to the CR pair especially near ωcr because in many parameter regimes there is a cutoff-resonance-cutoff (CRC) triplet that completely changes the wave absorption; and (b) the maximum MC efficiency does not always occur near k∥ ≈ k*∥∥.

  12. Electrostatic MEMS vibration energy harvester for HVAC applications with impact-based frequency up-conversion

    NASA Astrophysics Data System (ADS)

    Oxaal, J.; Hella, M.; Borca-Tasciuc, D.-A.

    2016-12-01

    This paper reports on electrostatic MEMS vibration energy harvesters with gap-closing interdigitated electrodes, designed for and tested on HVAC air ducts. The harvesters were fabricated on SOI wafers with 200 µm device layer using a custom microfabrication process. Designs with aspects ratio (electrodes’ gap versus depth) of 10 and 20 were implemented, while the overall footprint was approximately 1 cm  ×  1 cm in both cases. In order to enhance the power output, a dual-level physical stopper system was designed to control the minimum gap between the electrodes, which is a key parameter in the conversion process. The dual-level stopper utilizes cantilever beams to absorb a portion of the impact energy as the electrodes approach the impact point, and a film of parylene with nanometer thickness deposited on the electrode sidewalls. The parylene layer defines the absolute minimum gap and provides electrical insulation. The fabricated devices were first tested on a vibration shaker to characterize the resonant behavior. Devices with aspect ratio 10 were found to exhibit frequency up-conversion, which enhances the amount of converted power. Devices with both aspect ratios were found to exhibits spring hardening due to impact with the stoppers and spring softening behavior at increasing voltage bias. The highest power measured on shaker table for sinusoidal vibrations was 3.13 µW (includes enhancement due to frequency up-conversion driven by impact) for aspect ratio 10, and 0.166 µW for aspect ratio 20. The corresponding dimensional figure-of-merit, defined as the power output normalized to vibration acceleration and frequency, squared voltage and device mass, was in the range of 10 · 10-8 m V-2 for both devices, about an order of magnitude higher than state-of-the-art. Testing was carried out on HVAC air duct vibrating with an RMS acceleration of 155 mg RMS, a primary frequency of 60 Hz and a PSD of 7.15 · 10-2 g2 Hz-1. The peak power measured was

  13. Wavelength conversion through soliton self-frequency shift in tellurite microstructured fiber with picosecond pump pulse

    NASA Astrophysics Data System (ADS)

    Bi, Wanjun; Li, Xia; Xing, Zhaojun; Zhou, Qinling; Fang, Yongzheng; Gao, Weiqing; Xiong, Liangming; Hu, Lili; Liao, Meisong

    2016-01-01

    Wavelength conversion to the wavelength range that is not covered by commercially available lasers could be accomplished through the soliton self-frequency shift (SSFS) effect. In this study, the phenomenon of SSFS pumped by a picosecond-order pulse in a tellurite microstructured fiber is investigated both theoretically and experimentally. The balance between the dispersion and the nonlinearity achieved by a 1958 nm pump laser induces a distinct SSFS effect. Attributed to the large spectral distance between the pump pulse and the fiber zero-dispersion wavelength, the SSFS is not cancelled due to energy shedding from the soliton to the dispersive wave. Details about the physical mechanisms behind this phenomenon and the variations of the wavelength shift, the conversion efficiency are revealed based on numerical simulations. Owing to the large soliton number N, the pulse width of the first split fundamental soliton is approximately 40 fs, producing a pulse compression factor of ˜38, much higher than that pumped by a femtosecond pulse. Experiments were also conducted to confirm the validity of the simulation results. By varying the pump power, a continuous soliton shift from 1990 nm to 2264 nm was generated. The generation of SSFS in tellurite microstructured fibers with picosecond pump pulse can provide a new approach for wavelength conversion in the mid-infrared range and could be useful in medical and some other areas.

  14. Nonlinear optical frequency conversion with KTP and BiBO crystals for lasers in space

    NASA Astrophysics Data System (ADS)

    Potreck, Arne; Schröder, Helmut; Lammers, Melanie; Tzeremes, Georgios; Riede, Wolfgang

    2014-09-01

    Within ESA's ADM-Aeolus and EarthCARE missions Doppler-wind Lidar systems will be operated in the Earth's orbit to measure global wind profiles. The active instrument will be based on a Nd:YAG laser, frequency tripled by nonlinear optical crystals. Different crystals are therefore to compare and qualify in regard of their space acceptability. A dedicated set-up to measure the maximum conversion efficiencies and its stability during longterm operation for KTP crystals (SHG) and BiBO crystals (SHG and THG) is presented in this work. In order to detect gray-tracking and its influence on thermal lensing in situ, measurements with a Shack-Hartmann sensor and a co-aligned HeNe laser were performed. Conversion efficiencies were 76+/-3 % at SHG for KTP and BiBO crystals and 48+/-2 % at THG with a combination of two BiBO crystals. During longterm experiments of 60 million laser pulses, conversion efficiencies were demonstrated to be stable over time (+/-1 % at SHG with KTP and +/-2 % at THG with BiBO). The occurrence of gray-tracking was detected in the KTP crystal and the resulting thermal lensing with an exponential saturation over time was observed in situ.

  15. High voltage-power frequency electrical heating in-situ conversion technology of oil shale

    NASA Astrophysics Data System (ADS)

    Sun, Youhong; Yang, Yang; Lopatin, Vladimir; Guo, Wei; Liu, Baochang; Yu, Ping; Gao, Ke; Ma, Yinlong

    2014-05-01

    With the depletion of conventional energy sources,oil shale has got much attention as a new type of energy resource,which is rich and widespread in the world.The conventional utilization of oil shale is mainly focused on resorting to produce shale oil and fuel gas with low extraction efficiency about one in a million due to many shortcomings and limitations.And the in-situ conversion of oil shale,more environmentally friendly,is still in the experimental stage.High voltage-power frequency electrical heating in-situ conversion of oil shale is a new type of in-situ pyrolysis technology.The main equipment includes a high voltage-power frequency generator and interior reactor. The high voltage-power frequency generator can provide a voltage between 220-8000 V which can be adjusted in real time according to the actual situation.Firstly,high voltage is used to breakdown the oil shale to form a dendritic crack between two electrodes providing a conductive channel inside the oil shale rock.And then the power frequency(220V) is used to generate the electric current for heating the internal surface of conductive channel,so that the energy can be transmitted to the surrounding oil shale.When the temperature reaches 350 degree,the oil shale begins to pyrolysis.In addition,the temperature in the conductive channel can be extremely high with high voltage,which makes the internal surface of conductive channel graphitization and improves its heat conduction performance.This technology can successfully make the oil shale pyrolysis, based on a lot of lab experiments,and also produce the combustible shale oil and fuel gas.Compared to other in-situ conversion technology,this method has the following advantages: high speed of heating oil shale,the equipment underground is simple,and easy to operate;it can proceed without the limitation of shale thickness, and can be used especially in the thin oil shale reservoir;the heating channel is parallel to the oil shale layers,which has more

  16. Nanolaminated Permalloy Core for High-Flux, High-Frequency Ultracompact Power Conversion

    SciTech Connect

    Kim, J; Kim, M; Galle, P; Herrault, F; Shafer, R; Park, JY; Allen, MG

    2013-09-01

    Metallic magnetic materials have desirable magnetic properties, including high permeability, and high saturation flux density, when compared with their ferrite counterparts. However, eddy-current losses preclude their use in many switching converter applications, due to the challenge of simultaneously achieving sufficiently thin laminations such that eddy currents are suppressed (e.g., 500 nm-1 mu m for megahertz frequencies), while simultaneously achieving overall core thicknesses such that substantial power can be handled. A CMOS-compatible fabrication process based on robot-assisted sequential electrodeposition followed by selective chemical etching has been developed for the realization of a core of substantial overall thickness (tens to hundreds of micrometers) comprised of multiple, stacked permalloy (Ni80Fe20) nanolaminations. Tests of toroidal inductors with nanolaminated cores showed negligible eddy-current loss relative to total core loss even at a peak flux density of 0.5 T in the megahertz frequency range. To illustrate the use of these cores, a buck power converter topology is implemented with switching frequencies of 1-2 MHz. Power conversion efficiency greater than 85% with peak operating flux density of 0.3-0.5 T in the core and converter output power level exceeding 5 W was achieved.

  17. Observation of ion-cyclotron-frequency mode-conversion flow drive in tokamak plasmas.

    PubMed

    Lin, Y; Rice, J E; Wukitch, S J; Greenwald, M J; Hubbard, A E; Ince-Cushman, A; Lin, L; Porkolab, M; Reinke, M L; Tsujii, N

    2008-12-05

    Strong toroidal flow (Vphi) and poloidal flow (Vtheta) have been observed in D-3He plasmas with ion cyclotron range of frequencies (ICRF) mode-conversion (MC) heating on the Alcator C-Mod tokamak. The toroidal flow scales with the rf power Prf (up to 30 km/s per MW), and is significantly larger than that in ICRF minority heated plasmas at the same rf power or stored energy. The central Vphi responds to Prf faster than the outer regions, and the Vphi(r) profile is broadly peaked for r/a < or =0.5. Localized (0.3 < or = r/a < or =0.5) Vtheta appears when Prf > or =1.5 MW and increases with power (up to 0.7 km/s per MW). The experimental evidence together with numerical wave modeling suggests a local flow drive source due to the interaction between the MC ion cyclotron wave and 3He ions.

  18. Potential for efficient frequency conversion at high average power using solid state nonlinear optical materials

    SciTech Connect

    Eimerl, D.

    1985-10-28

    High-average-power frequency conversion using solid state nonlinear materials is discussed. Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude. For example, using KD*P, efficient doubling (>70%) of Nd:YAG at average powers approaching 100 KW is possible; and for doubling to the blue or ultraviolet regions, the average power may approach 1 MW. Configurations using segmented apertures permit essentially unlimited scaling of average power. High average power is achieved by configuring the nonlinear material as a set of thin plates with a large ratio of surface area to volume and by cooling the exposed surfaces with a flowing gas. The design and material fabrication of such a harmonic generator are well within current technology.

  19. Frequency conversion, nonlinear absorption and carrier dynamics of GaSe:B/Er crystals

    NASA Astrophysics Data System (ADS)

    Yuksek, Mustafa; Karatay, Ahmet; Ertap, Hüseyin; Elmali, Ayhan; Karabulut, Mevlut

    2017-04-01

    We aimed to investigate the influence of Er3+ rare earth element on the frequency conversion wavelength in boron doped GaSe crystals. It was found that by substitution of Er3+ with B3+, SHG signal shifted to higher wavelength. In addition, the nonlinear absorption properties and ultrafast dynamics of pure, 0.5 at% B3+ and 0.25 at% B3+ + 0.25 at% Er3+ doped GaSe crystals have been studied by open aperture Z-scan and ultrafast pump probe spectroscopy techniques. All of the studied crystals showed nonlinear absorption (NA). It was observed that 0.5 at% B3+ doped GaSe crystal showed bleach signal. This signal switched to NA signal with long life after substitution of 0.25 at% Er3+ with 0.25 at% B3+.

  20. On the propagation and mode conversion of auroral medium frequency bursts

    NASA Astrophysics Data System (ADS)

    Broughton, M. C.; LaBelle, J.; Kim, E.-H.; Yoon, P. H.; Johnson, J. R.; Cairns, I. H.

    2016-02-01

    Auroral medium frequency (MF) bursts are broadband, impulsive radio emissions associated with local substorm onsets. MF bursts consist of a characteristic fine structure whereby the higher frequencies arrive 10-100 ms before the lower frequencies. LaBelle (2011a) proposed that MF bursts originate as Langmuir/Z mode waves on the topside of the ionosphere that mode-convert to LO mode waves and propagate to ground level, with the fine structure resulting by propagation delays due to the topside ionospheric density profile. We investigate three aspects of this mechanism. First, full-wave calculations are used to simulate the MF burst fine structure using a realistic ionospheric density profile. The delay between the highest and lowest frequencies is 21 ms. This value is smaller than the experimentally determined delays of ˜100 ms presented in Bunch and LaBelle (2009), but differences between the topside electron number density profile used in the simulations and the number density profile during disturbed conditions make comparisons only approximate. Second, the Landau damping of Langmuir/Z mode waves on the topside ionosphere is calculated, assuming the electron distribution function consists of a cold background population (ne0) and a warm secondary population (nse). The Landau damping is small when nse/ne0 = 0.04% (consistent with Maggs and Lotko (1981)) but is significant when nse/ne0 > 0.4%. Finally, full-wave calculations are used to determine the mode conversion efficiency from Langmuir/Z mode waves to LO mode waves. These imply that waves would suffer an attenuation of wave energy density of approximately 5-10% if they are generated with their wave vectors in a narrow cone centered around the local magnetic field. Taken together, these calculations suggest that for small values of nse/ne0 <0.4%, the mechanism proposed by LaBelle (2011a) is a plausible explanation for the origin of MF bursts.

  1. Nanophotonics and nanochemistry: controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles.

    PubMed

    Chen, Guanying; Yang, Chunhui; Prasad, Paras N

    2013-07-16

    Nanophotonics is an emerging science dealing with the interaction of light and matter on a nanometer scale and holds promise to produce new generation nanophosphors with highly efficient frequency conversion of infrared (IR) light. Scientists can control the excitation dynamics by using nanochemistry to produce hierarchically built nanostructures and tailor their interfaces. These nanophosphors can either perform frequency up-conversion from IR to visible or ultraviolet (UV) or down-conversion, which results in the IR light being further red shifted. Nanophotonics and nanochemistry open up numerous opportunities for these photon converters, including in high contrast bioimaging, photodynamic therapy, drug release and gene delivery, nanothermometry, and solar cells. Applications of these nanophosphors in these directions derive from three main stimuli. Light excitation and emission within the near-infrared (NIR) "optical transparency window" of tissues is ideal for high contrast in vitro and in vivo imaging. This is due to low natural florescence, reduced scattering background, and deep penetration in tissues. Secondly, the naked eye is highly sensitive in the visible range, but it has no response to IR light. Therefore, many scientists have interest in the frequency up-conversion of IR wavelengths for security and display applications. Lastly, frequency up-conversion can convert IR photons to higher energy photons, which can then readily be absorbed by solar materials. Current solar devices do not use abundant IR light that comprises almost half of solar energy. In this Account, we present our recent work on nanophotonic control of frequency up- and down-conversion in fluoride nanophosphors, and their biophotonic and nanophotonic applications. Through nanoscopic control of phonon dynamics, electronic energy transfer, local crystal field, and surface-induced non-radiative processes, we were able to produce new generation nanophosphors with highly efficient frequency

  2. Efficient frequency conversion by stimulated Raman scattering in a sodium nitrate aqueous solution

    SciTech Connect

    Ganot, Yuval E-mail: ibar@bgu.ac.il; Bar, Ilana E-mail: ibar@bgu.ac.il

    2015-09-28

    Frequency conversion of laser beams, based on stimulated Raman scattering (SRS) is an appealing technique for generating radiation at new wavelengths. Here, we investigated experimentally the SRS due to a single pass of a collimated frequency-doubled Nd:YAG laser beam (532 nm) through a saturated aqueous solution of sodium nitrate (NaNO{sub 3}), filling a 50 cm long cell. These experiments resulted in simultaneous generation of 1st (564 nm) and 2nd (599 nm) Stokes beams, corresponding to the symmetric stretching mode of the nitrate ion, ν{sub 1}(NO{sub 3}{sup −}), with 40 and 12 mJ/pulse maximal converted energies, equivalent to 12% and 4% efficiencies, respectively, for a 340 mJ/pulse pump energy. The results indicate that the pump and SRS beams were thermally defocused and that four-wave mixing was responsible for the second order Stokes process onset.

  3. High-fidelity frequency down-conversion of visible entangled photon pairs with superconducting single-photon detectors

    SciTech Connect

    Ikuta, Rikizo; Kato, Hiroshi; Kusaka, Yoshiaki; Yamamoto, Takashi; Imoto, Nobuyuki; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Wang, Zhen; Fujiwara, Mikio; Sasaki, Masahide; Koashi, Masato

    2014-12-04

    We experimentally demonstrate a high-fidelity visible-to-telecommunicationwavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 nm is converted to a 1522-nm photon. Using superconducting single-photon detectors with low dark count rates and small timing jitters, we observed a fidelity of 0.93±0.04 after the wavelength conversion.

  4. Warm white LED light by frequency down-conversion of mixed yellow and red Lumogen

    NASA Astrophysics Data System (ADS)

    Mosca, Mauro; Caruso, Fulvio; Zambito, Leandro; Seminara, Biagio; Macaluso, Roberto; Calı, Claudio; Feltin, Eric

    2013-05-01

    This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on a mixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standard Ce:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issue today for LED-based lighting. Using photoluminescence of Lumogen® F Yellow 083, a perylene-based polymer dye commercialized by BASF, and adding a small quantity of another perylene-based dye, Lumogen® F Red 305 (BASF), we obtained high-efficiency warm white LEDs by yellow and red conversion from a standard 450 nm GaN/InGaN royal blue LED. Different weight proportions of dyes were dissolved in solutions with equal amounts of poly-methyl-methacrylate (PMMA) in ethyl acetate, then the LEDs were dip-coated in each solution and optically characterized. Record values of 8.03 lm of luminous flux and 116.11 lm/W of optical efficiency were achieved. Finally, the effects of both driving current, and pump wavelength on LED performances - such as chromatic coordinates, correlated color temperature, color rendering index (CRI), and optical efficiency - were investigated.

  5. Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

    NASA Astrophysics Data System (ADS)

    Manurkar, Paritosh

    Most of the existing protocols for quantum communication operate in a two-dimensional Hilbert space where their manipulation and measurement have been routinely investigated. Moving to higher-dimensional Hilbert spaces is desirable because of advantages in terms of longer distance communication capabilities, higher channel capacity and better information security. We can exploit the spatio-temporal degrees of freedom for the quantum optical signals to provide the higher-dimensional signals. But this necessitates the need for measurement and manipulation of multidimensional quantum states. To that end, there have been significant theoretical studies based on quantum frequency conversion (QFC) in recent years even though the experimental progress has been limited. QFC is a process that allows preservation of the quantum information while changing the frequency of the input quantum state. It has deservedly garnered a lot of attention because it serves as the connecting bridge between the communications band (C-band near 1550 nm) where the fiber-optic infrastructure is already established and the visible spectrum where high efficiency single-photon detectors and optical memories have been demonstrated. In this experimental work, we demonstrate mode-selective frequency conversion as a means to measure and manipulate photonic signals occupying d -dimensional Hilbert spaces where d=2 and 4. In the d=2 case, we demonstrate mode contrast between two temporal modes (TMs) which serves as the proof-of-concept demonstration. In the d=4 version, we employ six different TMs for our detailed experimental study. These TMs also include superposition modes which are a crucial component in many quantum key distribution protocols. Our method is based on producing pump pulses which allow us to upconvert the TM of interest while ideally preserving the other modes. We use MATLAB simulations to determine the pump pulse shapes which are subsequently produced by controlling the amplitude and

  6. Group velocity mismatch-absent nonlinear frequency conversions for mid-infrared femtosecond pulses generation

    PubMed Central

    Zhong, Haizhe; Zhang, Lifu; Li, Ying; Fan, Dianyuan

    2015-01-01

    A novel group velocity mismatch (GVM) absent scheme for nonlinear optical parametric procedure in mid-infrared was developed with type-I quasi phase matching by use of an off-digital nonlinear optical coefficient d31. This was achieved by matching of the group velocities of the pump and the signal waves, while the phase velocities were quasi phase matched. The system employs MgO-doped periodically poled LiNbO3 as the nonlinear medium. Desired group-velocity dispersion would be obtained via appropriately temperature regulation. To demonstrate its potential applications in ultrafast mid-infrared pulses generation, aiming at a typical mid-infrared wavelength of ~3.2 μm, design examples of two basic nonlinear frequency conversion procedures are studied for both the narrow-band seeding mid-IR optical parametric amplification (OPA) and the synchronously pumped femtosecond optical parametric oscillation (SPOPO). Compared with the conventional scheme of type-0 QPM, the quantum-efficiency can be more than doubled with nearly unlimited bandwidth. The proposed GVM- absent phase matching design may provide a promising route to efficient and broadband sub-100 fs mid-infrared ultrafast pulses generation without group-velocity walk-off. PMID:26099837

  7. Conversion of CO2 to CO using radio-frequency atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Foote, Alexander; Dedrick, James; O'Connell, Deborah; North, Michael; Gans, Timo

    2016-09-01

    Low temperature plasmas can be used for the in situ generation of CO, from relatively non-toxic CO2 . CO is very useful in many industrial chemical processes and so, via low temperature plasmas, CO2, a waste product, can be converted into a valuable chemical. The key challenges in using this method, for CO production, are optimising the energy efficiency, maximising the conversion of CO2 into CO and then separating the CO from the other species produced in the plasma. Very high yields of CO, greater than 90%, have been achieved at atmospheric pressure using argon as a carrier gas with admixtures up to 1.5% with energy efficiencies of up to 4%. The plasma generated in continuous and spatially homogeneous and is driven at a frequency of 40.68 MHz. A zero dimensional global model has also been used to simulate the chemical kinetics of the plasma to determine the dominant dissociation processes and is in good agreement with the experimentally determined yields. The model is used to determine how important a role the vibrational states of CO2 are, in a highly collisional plasma, to the production of CO and there can provide insight into how to improve the energy efficiency and suppress unwanted reactions.

  8. Ion-photon entanglement and quantum frequency conversion with trapped Ba+ ions.

    PubMed

    Siverns, J D; Li, X; Quraishi, Q

    2017-01-20

    Trapped ions are excellent candidates for quantum nodes, as they possess many desirable features of a network node including long lifetimes, on-site processing capability, and production of photonic flying qubits. However, unlike classical networks in which data may be transmitted in optical fibers and where the range of communication is readily extended with amplifiers, quantum systems often emit photons that have a limited propagation range in optical fibers and, by virtue of the nature of a quantum state, cannot be noiselessly amplified. Here, we first describe a method to extract flying qubits from a Ba+ trapped ion via shelving to a long-lived, low-lying D-state with higher entanglement probabilities compared with current strong and weak excitation methods. We show a projected fidelity of ≈89% of the ion-photon entanglement. We compare several methods of ion-photon entanglement generation, and we show how the fidelity and entanglement probability varies as a function of the photon collection optic's numerical aperture. We then outline an approach for quantum frequency conversion of the photons emitted by the Ba+ ion to the telecommunication range for long-distance networking and to 780 nm for potential entanglement with rubidium-based quantum memories. Our approach is significant for extending the range of quantum networks and for the development of hybrid quantum networks compromised of different types of quantum memories.

  9. Frequency conversion between UV and telecom wavelengths in a lithium niobate waveguide for quantum communication with Yb+ trapped ions

    NASA Astrophysics Data System (ADS)

    Kasture, Sachin; Lenzini, Francesco; Haylock, Ben; Boes, Andreas; Mitchell, Arnan; Streed, Erik W.; Lobino, Mirko

    2016-10-01

    We study and demonstrate the frequency conversion of UV radiation, resonant with 369.5 nm transition in Yb+ ions to the C-band wavelength 1580.3 nm and vice-versa using a reverse proton-exchanged waveguide in periodically poled lithium niobate. Our integrated device can interface trapped Yb+ ions with a telecom infrastructure for the realization of an Yb+ based quantum repeater protocol and to efficiently distribute entanglement over long distances. We analyse the single photon frequency conversion efficiency from the 369.525 nm to the telecom wavelength and its dependence on pump power, device length and temperature. The single-photon noise generated by the spontaneous Raman scattering of the pump is also measured. From this analysis we estimate a single photon conversion efficiency of ∼9% is achievable with our technology with almost complete suppression of the Raman noise.

  10. Nonlinear Dynamics of Photonics for Optical Signal Processing - Optical Frequency Conversion and Optical DSB-to-SSB Conversion

    DTIC Science & Technology

    2015-09-17

    Multiplexing, Optical Amplifier , Terahertz Electronics, Four-wave mixing, Radio-over-fiber networks, Intensity-asymmetry 16. SECURITY CLASSIFICATION OF: 17...structure and operation. For the photonic microwave amplification, we have demonstrated that microwaves can be amplified “photonically” by up to 30 dB for...linewidth and stability. 3. Photonic microwave amplification: Goals: To “photonically” amplify microwaves for a broad frequency range, from a few tens

  11. Effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency based nonlinear frequency conversion in quantum ring

    NASA Astrophysics Data System (ADS)

    Gumber, Sukirti; Gambhir, Monica; Jha, Pradip Kumar; Mohan, Man

    2016-10-01

    We study the combined effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency in quantum ring. The high flexibility in size and shape of ring makes it possible to fabricate a nearly perfect two-dimensional quantum structure. We also explore the dependence of frequency conversion, measured in terms of third order nonlinear susceptibility χ(3) , on coupling field, hydrostatic pressure and magnetic field. Although, a dip in χ(3) is observed with the introduction of strong coupling field, it renders the ring structure transparent to generated wave thus effectively enhancing the output of nonlinear frequency conversion process. At a fixed coupling strength, the output can be further enhanced by increasing the magnetic field while it shows an inverse relationship with pressure. These parameters, being externally controlled, provide an easy handle to control the output of quantum ring which can be used as frequency converter in communication networks.

  12. The effects of oblique incidences on the XB mode conversion in the electron cyclotron range of frequency

    NASA Astrophysics Data System (ADS)

    Jia, Guozhang; Gao, Zhe

    2017-02-01

    The linear conversion from a fast extraordinary mode to a Bernstein mode (XB) in the electron cyclotron range of frequency is revisited numerically by using a simplified kinetic model. The corresponding wave equations are solved as a standard two-point boundary value problem, where the self-consistent boundary conditions are applied and the scattering coefficients are calculated accordingly. The numerical calculation of the XB conversion efficiency is compared with the analytical formula for the normal incidence (along the direction perpendicular to the equilibrium magnetic field and parallel to the density gradient), where a reasonable agreement is found. The effects of incident angles represented by refractive indexes on the conversion efficiency are analyzed. It is shown that as the incident angle deviates from the normal incidence, the efficiency of XB conversion decreases significantly. The results also indicate that the power loss in the XB process can be ascribed to the reflected fast extraordinary mode and the reflected-converted ordinary mode. The symmetry of the conversion efficiency about the incident angle is discussed, and the rigid restriction on the scale length of the density variation for effective XB conversions can be possibly alleviated through altering the injection direction in realistic experiments.

  13. O-X mode conversion in a non-symmetric torus at electron cyclotron frequencies

    NASA Astrophysics Data System (ADS)

    Weitzner, Harold

    2017-02-01

    Previous work on this topic, [Weitzner, Phys. Plasmas 11, 866 (2004)], applicable in a system with toroidal symmetry, is extended to the case of a non-symmetric background equilibrium state. Maxwell's equations with the cold plasma dielectric tensor are used to represent the plasma-electromagnetic wave interaction. Away from the mode conversion region, geometrical optics adequately characterizes the wave propagation. A new, simpler derivation of the wave equations in the mode conversion region is given. Aside from one very special case in which a general plasma equilibrium behaves like a stratified medium, the previous results apply and highly effective mode conversion is found. The matching of the mode conversion solution to the geometrical optics solution, not previously examined, is discussed. A relatively weak condition on the perpendicular wave number near the resonance layer is found. Provided that the perpendicular wave number is small, it tends to zero at the mode conversion layer and the solutions match effectively.

  14. Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

    SciTech Connect

    Jia, Guozhang; Xiang, Nong; Huang, Yueheng; Wang, Xueyi; Lin, Yu

    2016-01-15

    The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparable to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ∼ 3ω{sub LH}, where ω{sub LH} represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ∼ 1.3ω{sub LH}), the generations of the high harmonic modes and sidebands through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.

  15. Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

    NASA Astrophysics Data System (ADS)

    Jia, Guozhang; Xiang, Nong; Wang, Xueyi; Huang, Yueheng; Lin, Yu

    2016-01-01

    The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparable to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ˜ 3ωLH, where ωLH represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ˜ 1.3ωLH), the generations of the high harmonic modes and sidebands through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.

  16. Telecom-band two-photon Michelson interferometer using frequency entangled photon pairs generated by spontaneous parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Yoshizawa, Akio; Fukuda, Daiji; Tsuchida, Hidemi

    2014-02-01

    We demonstrate a telecom-band fiber-optic two-photon Michelson interferometer using near-degenerate and collinear photon pairs with frequency entanglement. For spontaneous parametric down-conversion (SPDC), a continuous-wave laser diode pumps a periodically poled lithium niobate waveguide. Two threshold single-photon detectors record coincidence counts to observe two-photon interference and evaluate the correlation function. Multi-pair emission events are inevitable in SPDC and photon pairs without frequency entanglement are unintentionally registered as coincidence counts. In the demonstrated experiment, a mixture of photon pairs with and without frequency entanglement is present. The effects of such a mixed state on the correlation function are experimentally investigated. Two-photon interference of photon pairs without frequency entanglement is also measured for comparison.

  17. Development of High Efficient, Compact, Robust and Tunable IR and Terahertz Light Sources using Periodically Polled Frequency Conversion Devices

    DTIC Science & Technology

    2010-07-20

    lithium tantalate ( SLT ) originally developed in National Institute of Material Science (NIMS) for developing wide aperture frequency conversion...Terahertz light using Mg- doped SLT crystal. According to the background above, we performed the program setting two titles of thrusts as below...m using Mg-doped SLT crystal. Figure 3 shows the first light from the QPM-based OPO device. The visible red light is created by the mixing of the

  18. Octave-spanning coherent mid-IR generation via adiabatic difference frequency conversion.

    PubMed

    Suchowski, Haim; Krogen, Peter R; Huang, Shu-Wei; Kärtner, Franz X; Moses, Jeffrey

    2013-11-18

    We demonstrate efficient downconversion of a near-IR broadband optical parametric chirped pulse amplifier (OPCPA) pulse to a 1.1-octave-spanning mid-IR pulse (measured at -10 dB of peak) via a single nonlinearly and adiabatically chirped quasi-phase-matching grating in magnesium oxide doped lithium niobate. We report a spectrum spanning from 2 to 5 μm and obtained by near full photon number conversion of μJ-energy OPCPA pulses spanning 680-870 nm mixed with a narrowband 1047-nm pulse. The conversion process is shown to be robust for various input broadband OPA pulses and suitable for post-amplification conversion for many near-IR systems.

  19. O-X mode conversion in a non-symmetric torus at electron cyclotron frequencies

    NASA Astrophysics Data System (ADS)

    Weitzner, Harold

    2016-10-01

    Earlier work on linear wave propagation over a symmetric background state, is simplified and extended to non-symmetric equilibria. With the exception of one special case, which reduces to the case of a perpendicularly stratified medium, it is shown that mode conversion in symmetric or non-symmetric equilibria satisfies the same set of equations. An examination of the coupling of the geometrical ray optics solution to the mode conversion system provides a relatively simple and physical characterization of the incoming wave structure necessary to achieve effective mode conversion. Part of the work was done while visiting the Max=Planck-Insititute-for Plasmaphysics, Greifswald , Germany. its support is gratefully acknowledged. DE-FG-86ER53223.

  20. Design and characterisation of a piezoelectric knee-joint energy harvester with frequency up-conversion through magnetic plucking

    NASA Astrophysics Data System (ADS)

    Kuang, Yang; Yang, Zhihao; Zhu, Meiling

    2016-08-01

    Piezoelectric energy harvesting from human motion is challenging because of the low energy conversion efficiency at a low-frequency excitation. Previous studies by the present authors showed that mechanical plucking of a piezoelectric bimorph cantilever was able to provide frequency up-conversion from a few hertz to the resonance frequency of the cantilever, and that a piezoelectric knee-joint energy harvester (KEH) based on this mechanism was able to generate sufficient energy to power a wireless sensor node. However, the direct contact between the bimorph and the plectra leads to reduced longevity and considerable noise. To address these limitations, this paper introduces a magnetic plucking mechanism to replace the mechanical plucking in the KEH, where primary magnets (PM) actuated by knee-joint motion excite the bimorphs through a secondary magnet (SM) fixed on the bimorphs tip and so achieve frequency up-conversion. The key parameters of the new KEH that affect the energy output of a plucked bimorph were investigated. It was found that the bimorph plucked by a repulsive magnetic force produced a higher energy output than an attractive force. The energy output peaked at 32 PMs and increased with a decreasing gap between PM and SM as well as an increasing rotation speed of the PMs. Based on these investigations, a KEH with high energy output was prototyped, which featured 8 piezoelectric bimorphs plucked by 32 PMs through repulsive magnetic forces. The gap between PM and SM was set to 1.5 mm with a consideration on both the energy output and longevity of the bimorphs. When actuated by knee-joint motion of 0.9 Hz, the KEH produced an average power output of 5.8 mW with a life time >7.3 h (about 3.8 × 105 plucking excitations).

  1. Frequency of Use Leads to Automaticity of Production: Evidence from Repair in Conversation

    ERIC Educational Resources Information Center

    Kapatsinski, Vsevolod

    2010-01-01

    In spontaneous speech, speakers sometimes replace a word they have just produced or started producing by another word. The present study reports that in these replacement repairs, low-frequency replaced words are more likely to be interrupted prior to completion than high-frequency words, providing support to the hypothesis that the production of…

  2. Laser frequency down-conversion by means of a monochromatically driven two-level system

    NASA Astrophysics Data System (ADS)

    Soldatov, Andrey V.

    2016-09-01

    Conditions are found under which a simple two-level quantum system possessing dipole moment operator with permanent non-equal diagonal matrix elements and driven by external semiclassical monochromatic high-frequency EM (laser) field can radiate continuously at much lower frequency. Possible ways to experimental observation and practical implementation of the predicted effect for a wide range of applications are discussed.

  3. Efficient continuous-wave nonlinear frequency conversion in high-Q gallium nitride photonic crystal cavities on silicon

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Sabry; Simbula, Angelica; Carlin, Jean-François; Minkov, Momchil; Gerace, Dario; Savona, Vincenzo; Grandjean, Nicolas; Galli, Matteo; Houdré, Romuald

    2017-03-01

    We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG) and third harmonic generation (THG) in suspended gallium nitride slab photonic crystal (PhC) cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4 × 104, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving a normalized conversion efficiency of 2.4 × 10-3 W-1, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  4. Low phase noise microwave extraction from femtosecond laser by frequency conversion pair and IF-domain processing.

    PubMed

    Dai, Yitang; Cen, Qizhuang; Wang, Lei; Zhou, Yue; Yin, Feifei; Dai, Jian; Li, Jianqiang; Xu, Kun

    2015-12-14

    Extraction of a microwave component from a low-time-jitter femtosecond pulse train has been attractive for current generation of spectrally pure microwave. In order to avoid the transfer from the optical amplitude noise to microwave phase noise (AM-PM), we propose to down-convert the target component to intermediate frequency (IF) before the opto-electronic conversion. Due to the much lower carrier frequency, the AM-PM is greatly suppressed. The target is then recovered by up-conversion with the same microwave local oscillation (LO). As long as the time delay of the second LO matches that of the IF carrier, the phase noise of the LO shows no impact on the extraction process. The residual noise of the proposed extraction is analyzed in theory, which is also experimentally demonstrated as averagely around -155 dBc/Hz under offset frequency larger than 1 kHz when 10-GHz tone is extracted from a home-made femtosecond fiber laser. Large tunable extraction from 1 GHz to 10 GHz is also reported.

  5. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, Stanley; Craxton, R. Stephen; Soures, John

    1990-01-01

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.

  6. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, S.; Craxton, R.S.; Soures, J.

    1990-10-02

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temporal oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation. 16 figs.

  7. Fully-resonant, tunable, monolithic frequency conversion as a coherent UVA source.

    PubMed

    Zielińska, Joanna A; Zukauskas, Andrius; Canalias, Carlota; Noyan, Mehmet A; Mitchell, Morgan W

    2017-01-23

    We demonstrate a monolithic frequency converter incorporating up to four tuning degrees of freedom, three temperature and one strain, allowing resonance of pump and generated wavelengths simultaneous with optimal phase-matching. With a Rb-doped periodically-poled potassium titanyl phosphate (KTP) implementation, we demonstrate efficient continuous-wave second harmonic generation from 795 to 397, with low-power efficiency of 72% and high-power slope efficiency of 4.5%. The measured performance shows good agreement with theoretical modeling of the device. We measure optical bistability effects, and show how they can be used to improve the stability of the output against pump frequency and amplitude variations.

  8. Particle-in-cell simulation for frequency up-conversion of microwave pulse in a rapidly created plasma

    NASA Astrophysics Data System (ADS)

    Chen, Kun; Liu, Chunliang; Gao, Mingzhu; Chang, Chao

    2017-03-01

    Microwave pulse propagation through a rapidly created plasma and frequency up-conversion has been demonstrated by the particle-in-cell (PIC) method. Compared with the finite-difference time-domain method in which the time-varying plasma is simplified as a dielectric medium, the PIC method considering the interaction and motion of charged particles would be much closer to the experimental values. It is found that the source wave amplitude has a stable range to obtain the stable output. If the source wave amplitude is below 103 V/m with the plasma density of 4 ×1019m-3 , the output is mainly the plasma noise. Moreover, the higher amplitude source wave beyond 108 V/m would break the spatial distribution of the plasma so as to have an influence on the conversion efficiency. The stable range of source wave amplitude is affected by the plasma density. The power loss will increase with the increase in the plasma density in the PIC method, and it is more convenient and accurate to discuss the effects of the collision frequency.

  9. Frequency Conversion of Short Optical Pulses in Negatively Spatially Dispersive Metamaterials

    DTIC Science & Technology

    2015-10-22

    possible realization of the outlined approach is a plasmonic metaslab made of carbon nanotubes . It can be viewed as a plasmonic wave guide formed by a...metal plate (bottom) and by air (top) tampered by standing carbon nanotubes [7]. Such a structure supports different EM eigenmodes in the THz and mid...maintain negative dispersion. Frequencies and gaps between the modes can be tailored by changing lengths and spacing between the nanotubes so that phase

  10. Shaping pulses using frequency conversion with a modulated picosecond free electron laser

    SciTech Connect

    Hooper, B.A.; Madey, J.M.J.

    1995-12-31

    Computer simulations and experiments indicate that we can shape the infrared picosecond pulses of the Mark III FEL in amplitude, frequency, and phase. Strongly modulated fundamental and second harmonic pulses have been generated by operating the Mark III FEL in the regime of strong sideband growth. In this paper, we present the results of simulations and experiments for second harmonic generation with fundamental inputs from 2 to 3 {mu}m.

  11. Design and Simulation of Bistable Microsystem with Frequency-up conversion effect for Electrostatic Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Vysotskyi, Bogdan; Parrain, Fabien; Lefeuvre, Elie; Leroux, Xavier; Aubry, Denis; Gaucher, Philippe

    2016-10-01

    This work is dedicated for the study of energy harvesters implemented in form of microelectromechanical systems (MEMS) used to harvest ambient vibrations for powering standalone electronic devices. The previewed application is to power a leadless pacemaker with mechanical energy of the heartbeat, which requires the amount of power typically more than 1μW. The target of the presented article is to combine the effect of bistability and nonlinear coupling by electrostatic effect in order to achieve the high value of bandwidth at the low frequency under the low accelerations. Such system is expected to bring high power density performance. This study is performed mostly by numerical simulation.

  12. Note: Direct sensor resistance-to-frequency conversion with generalized impedance converter.

    PubMed

    Ramírez Muñoz, D; Sánchez Moreno, J; Casans Berga, S; Navarro Antón, A E

    2010-12-01

    In this note a squared output signal is generated from an astable circuit. Its frequency has a linear dependence on the resistance value of a resistive temperature sensor. The main circuit to obtain this direct relationship is the generalized impedance converter configured as a capacitor controlled by a sensor resistance. The proposed measurement method allows a direct analog-to-digital interface of information involved in resistive sensors. The converter finds applications in portable low voltage and low power design of instrumentation electronic systems.

  13. High-frequency thermal-electrical cycles for pyroelectric energy conversion

    SciTech Connect

    Bhatia, Bikram; Damodaran, Anoop R.; Cho, Hanna; Martin, Lane W.; King, William P.

    2014-11-21

    We report thermal to electrical energy conversion from a 150 nm thick BaTiO{sub 3} film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 μs. The rapid electric field changes as high as 11 × 10{sup 5 }kV/cm-s, and temperature change rates as high as 6 × 10{sup 5 }K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems.

  14. Demonstrations of analog-to-digital conversion using a frequency domain stretched processor.

    PubMed

    Reibel, Randy Ray; Harrington, Calvin; Dahl, Jason; Ostrander, Charles; Roos, Peter Aaron; Berg, Trenton; Mohan, R Krishna; Neifeld, Mark A; Babbitt, Wm R

    2009-07-06

    The first proof-of-concept demonstrations are presented for a broadband photonic-assisted analog-to-digital converter (ADC) based on spatial spectral holography (SSH). The SSH-ADC acts as a frequency-domain stretch processor converting high bandwidth input signals to low bandwidth output signals, allowing the system to take advantage of high performance, low bandwidth electronic ADCs. Demonstrations with 50 MHz effective bandwidth are shown to highlight basic performance with approximately 5 effective bits of vertical resolution. Signal capture with 1600 MHz effective bandwidth is also shown. Because some SSH materials span over 100 GHz and have large time apertures (approximately 10 micros), this technique holds promise as a candidate for the next generation of ADCs.

  15. Widely tunable frequency conversion in monolithic semiconductor waveguides at 2.4  μm.

    PubMed

    Abolghasem, Payam; Kang, Dongpeng; Logan, Dylan F; Lungwitz, Mandy; Helmy, Amr S

    2014-06-15

    We report on the generation of continuous-wave widely tunable light between 2360 and 2530 nm using difference-frequency generation with a pump tuned between 938 and 952 nm and a signal tuned between 1490 and 1590 nm in a type-II phase-matched monolithic semiconductor waveguide. The device internal conversion efficiency is estimated to be 0.29%  W(-1)  cm(-2). This design which uses a single-sided Bragg reflection waveguide has the potential for on-chip spectroscopy, as well as environmental monitoring applications, where a tunable source of coherent radiation tuned between 2 and 3 μm wavelength is desired.

  16. Diffraction-limited real-time terahertz imaging by optical frequency up-conversion in a DAST crystal.

    PubMed

    Fan, Shuzhen; Qi, Feng; Notake, Takashi; Nawata, Kouji; Takida, Yuma; Matsukawa, Takeshi; Minamide, Hiroaki

    2015-03-23

    Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and the arts. This report describes real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in an organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate (DAST) crystal, with high resolution reaching the diffraction limit. THz-wave images were converted to the near infrared region and then captured using an InGaAs camera in a tandem imaging system. The resolution of the imaging system was analyzed. Diffraction and interference of THz wave were observed in the experiments. Videos are supplied to show the interference pattern variation that occurs with sample moving and tilting.

  17. Cascade photonic integrated circuit architecture for electro-optic in-phase quadrature/single sideband modulation or frequency conversion.

    PubMed

    Hasan, Mehedi; Hall, Trevor

    2015-11-01

    A photonic integrated circuit architecture for implementing frequency upconversion is proposed. The circuit consists of a 1×2 splitter and 2×1 combiner interconnected by two stages of differentially driven phase modulators having 2×2 multimode interference coupler between the stages. A transfer matrix approach is used to model the operation of the architecture. The predictions of the model are validated by simulations performed using an industry standard software tool. The intrinsic conversion efficiency of the proposed design is improved by 6 dB over the alternative functionally equivalent circuit based on dual parallel Mach-Zehnder modulators known in the prior art. A two-tone analysis is presented to study the linearity of the proposed circuit, and a comparison is provided over the alternative. The proposed circuit is suitable for integration in any platform that offers linear electro-optic phase modulation such as LiNbO(3), silicon, III-V, or hybrid technology.

  18. Frequency domain near-infrared multiwavelength imager design using high-speed, direct analog-to-digital conversion

    PubMed Central

    Zimmermann, Bernhard B.; Fang, Qianqian; Boas, David A.; Carp, Stefan A.

    2016-01-01

    Abstract. Frequency domain near-infrared spectroscopy (FD-NIRS) has proven to be a reliable method for quantification of tissue absolute optical properties. We present a full-sampling direct analog-to-digital conversion FD-NIR imager. While we developed this instrument with a focus on high-speed optical breast tomographic imaging, the proposed design is suitable for a wide-range of biophotonic applications where fast, accurate quantification of absolute optical properties is needed. Simultaneous dual wavelength operation at 685 and 830 nm is achieved by concurrent 67.5 and 75 MHz frequency modulation of each laser source, respectively, followed by digitization using a high-speed (180  MS/s) 16-bit A/D converter and hybrid FPGA-assisted demodulation. The instrument supports 25 source locations and features 20 concurrently operating detectors. The noise floor of the instrument was measured at <1.4  pW/√Hz, and a dynamic range of 115+ dB, corresponding to nearly six orders of magnitude, has been demonstrated. Titration experiments consisting of 200 different absorption and scattering values were conducted to demonstrate accurate optical property quantification over the entire range of physiologically expected values. PMID:26813081

  19. Potential of high-frequency ultrasounds to improve sludge anaerobic conversion and surfactants removal at different food/inoculum ratio.

    PubMed

    Gallipoli, A; Gianico, A; Gagliano, M C; Braguglia, C M

    2014-05-01

    High-frequency ultrasounds have recently gained interest as oxidative technique for sonochemical degradation of organic contaminants in water. In this study an innovative approach applying 200 kHz ultrasounds to improve both sludge anaerobic biodegradability and decontamination is proposed. Digestion tests were performed on batch reactors fed either with untreated or sonicated sludge, at different food/inoculum (F/I) ratio, in the range 0.3-0.9. First order kinetic highlighted a decreasing trend of the hydrolysis rate by increasing F/I, both for untreated and sonicated sludge. Positive effect of ultrasounds on specific biogas production was evident, but the conversion rate for pretreated sludge was strongly affected by F/I, and decreased by increasing F/I. Anionic surfactants anaerobic removal occurred in all tests, but the effect of ultrasounds was significant only at F/I=0.3. By pretreating sludge with high frequency ultrasounds, low F/I was the ideal ratio improving both sludge anaerobic digestion and decontamination.

  20. Frequency domain near-infrared multiwavelength imager design using high-speed, direct analog-to-digital conversion

    NASA Astrophysics Data System (ADS)

    Zimmermann, Bernhard B.; Fang, Qianqian; Boas, David A.; Carp, Stefan A.

    2016-01-01

    Frequency domain near-infrared spectroscopy (FD-NIRS) has proven to be a reliable method for quantification of tissue absolute optical properties. We present a full-sampling direct analog-to-digital conversion FD-NIR imager. While we developed this instrument with a focus on high-speed optical breast tomographic imaging, the proposed design is suitable for a wide-range of biophotonic applications where fast, accurate quantification of absolute optical properties is needed. Simultaneous dual wavelength operation at 685 and 830 nm is achieved by concurrent 67.5 and 75 MHz frequency modulation of each laser source, respectively, followed by digitization using a high-speed (180 MS/s) 16-bit A/D converter and hybrid FPGA-assisted demodulation. The instrument supports 25 source locations and features 20 concurrently operating detectors. The noise floor of the instrument was measured at <1.4 pW/√Hz, and a dynamic range of 115+ dB, corresponding to nearly six orders of magnitude, has been demonstrated. Titration experiments consisting of 200 different absorption and scattering values were conducted to demonstrate accurate optical property quantification over the entire range of physiologically expected values.

  1. New Crystalline Materials for Nonlinear Frequency Conversion, Electro-Optic Modulation, and Mid-Infrared Gain Media

    SciTech Connect

    Adams, J

    2002-08-09

    New crystalline materials were investigated for applications in frequency conversion of near-infrared wavelengths and as gain media for tunable mid-infrared solid-state lasers. GaCa{sub 4}O(BO{sub 3}){sub 3} (GdCOB), YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB), LaCa{sub 4}O(BO{sub 3}){sub 3} (LaCOB), and Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} were characterized for frequency conversion of 1 {micro}m lasers. For type I doubling at 1064 nm, LaCOB, GdCOB, and YCOB were found to have effective coupling coefficients (d{sub eff}) of 0.52 {+-} 0.05, 0.78 {+-} 0.06, and 1.12 {+-} 0.07 pm/V, respectively. LaCOB was measured to have angular and thermal sensitivities of 1224 {+-} 184 (cm-rad){sup -1} and < 0.10 (cm-{sup o}C){sup -1}, respectively. The effective coupling coefficient for type II noncritically phasematched (NCPM) doubling at 1064 nm in Gd{sub 0.275}Y{sub 0.725}Ca{sub 4}O(BO{sub 3}){sub 3} was measured to be 0.37 {+-} 0.04 pm/V. We predict LaCOB to have a type I NCPM fundamental wavelength of 1042 {+-} 1.5 nm. Due to its low angular and thermal sensitivities for doubling near 1047 nm, LaCOB has potential for frequency doubling of high-average power Nd:LiYF{sub 4} and Yb:Sr{sub 5}(P0{sub 4}){sub 3}F lasers. LaCOB, GdCOB, and YCOB were also investigated for optical parametric oscillator applications and we determined that they may have potential in a Ti:sapphire pumped oscillator. The effective linear electro-optic coefficients (r{sub eff}) were measured along dielectric directions in YCOB and a maximum r{sub eff} of 10.8 pm/V was found. For a crystal with a 5:1 aspect ratio, the corresponding half-wave voltage at 1064 nm would be 19.6 kV. Therefore a Pockels cell composed of two YCOB crystals with 5:1 aspect ratios would have a required half-wave voltage <10 kV. Moderate coupling coefficients (3 x KH{sub 2}PO{sub 4}), low thermal sensitivities, ease of growth to large sizes, non-hygroscopicity, and favorable polishing and coating characteristics make La

  2. Frequency down-conversion of 637 nm light to the telecommunication band for non-classical light emitted from NV centers in diamond.

    PubMed

    Ikuta, Rikizo; Kobayashi, Toshiki; Yasui, Shuto; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Fujiwara, Mikio; Yamamoto, Takashi; Koashi, Masato; Sasaki, Masahide; Wang, Zhen; Imoto, Nobuyuki

    2014-05-05

    We demonstrate a low-noise frequency down-conversion of photons at 637 nm to the telecommunication band at 1587 nm by the difference frequency generation in a periodically-poled lithium niobate. An internal conversion efficiency of the converter is estimated to be 0.44 at the maximum which is achieved by a pump power of 0.43 W, whereas a rate of internal background photons caused by the strong cw pump laser is estimated to be 9 kHz/mW within a bandwidth of about 1 nm. By using the experimental values related to the intrinsic property of the converter, and using the intensity correlation and the average photon number of a 637 nm input light pulse, we derive the intensity correlation of a converted telecom light pulse. Then we discuss feasibility of a single-photon frequency conversion to the telecommunication band for a long-distance quantum communication based on NV centers in diamond.

  3. Gene conversion and deletion frequencies during double-strand break repair in human cells are controlled by the distance between direct repeats.

    PubMed

    Schildkraut, Ezra; Miller, Cheryl A; Nickoloff, Jac A

    2005-01-01

    Homologous recombination (HR) repairs DNA double-strand breaks and maintains genome stability. HR between linked, direct repeats can occur by gene conversion without an associated crossover that maintains the gross repeat structure. Alternatively, direct repeat HR can occur by gene conversion with a crossover, or by single-strand annealing (SSA), both of which delete one repeat and the sequences between the repeats. Prior studies of different repeat structures in yeast and mammalian cells revealed disparate conversion:deletion ratios. Here, we show that a key factor controlling this ratio is the distance between the repeats, with conversion frequency increasing linearly with the distances from 850 to 3800 bp. Deletions are thought to arise primarily by SSA, which involves extensive end-processing to reveal complementary single-strands in each repeat. The results can be explained by a model in which strand-invasion leading to gene conversion competes more effectively with SSA as more extensive end-processing is required for SSA. We hypothesized that a transcription unit between repeats would inhibit end-processing and SSA, thereby increasing the fraction of conversions. However, conversion frequencies were identical for direct repeats separated by 3800 bp of transcriptionally silent or active DNA, indicating that end-processing and SSA are not affected by transcription.

  4. Efficiency of non-linear frequency conversion of double-scale pico-femtosecond pulses of passively mode-locked fiber laser.

    PubMed

    Smirnov, Sergey V; Kobtsev, Sergey M; Kukarin, Sergey V

    2014-01-13

    For the first time we report the results of both numerical simulation and experimental observation of second-harmonic generation as an example of non-linear frequency conversion of pulses generated by passively mode-locked fiber master oscillator in different regimes including conventional (stable) and double-scale (partially coherent and noise-like) ones. We show that non-linear frequency conversion efficiency of double-scale pulses is slightly higher than that of conventional picosecond laser pulses with the same energy and duration despite strong phase fluctuations of double-scale pulses.

  5. Glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals for frequency conversion of lasers

    PubMed Central

    Fang, Zaijin; Xiao, Xusheng; Wang, Xin; Ma, Zhijun; Lewis, Elfed; Farrell, Gerald; Wang, Pengfei; Ren, Jing; Guo, Haitao; Qiu, Jianrong

    2017-01-01

    A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers. PMID:28358045

  6. Glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals for frequency conversion of lasers.

    PubMed

    Fang, Zaijin; Xiao, Xusheng; Wang, Xin; Ma, Zhijun; Lewis, Elfed; Farrell, Gerald; Wang, Pengfei; Ren, Jing; Guo, Haitao; Qiu, Jianrong

    2017-03-30

    A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers.

  7. Full 3D modelling of pulse propagation enables efficient nonlinear frequency conversion with low energy laser pulses in a single-element tripler.

    PubMed

    Kardaś, Tomasz M; Nejbauer, Michał; Wnuk, Paweł; Resan, Bojan; Radzewicz, Czesław; Wasylczyk, Piotr

    2017-02-22

    Although new optical materials continue to open up access to more and more wavelength bands where femtosecond laser pulses can be generated, light frequency conversion techniques are still indispensable in filling the gaps on the ultrafast spectral scale. With high repetition rate, low pulse energy laser sources (oscillators) tight focusing is necessary for a robust wave mixing and the efficiency of broadband nonlinear conversion is limited by diffraction as well as spatial and temporal walk-off. Here we demonstrate a miniature third harmonic generator (tripler) with conversion efficiency exceeding 30%, producing 246 fs UV pulses via cascaded second order processes within a single laser beam focus. Designing this highly efficient and ultra compact frequency converter was made possible by full 3-dimentional modelling of propagation of tightly focused, broadband light fields in nonlinear and birefringent media.

  8. Full 3D modelling of pulse propagation enables efficient nonlinear frequency conversion with low energy laser pulses in a single-element tripler

    PubMed Central

    Kardaś, Tomasz M.; Nejbauer, Michał; Wnuk, Paweł; Resan, Bojan; Radzewicz, Czesław; Wasylczyk, Piotr

    2017-01-01

    Although new optical materials continue to open up access to more and more wavelength bands where femtosecond laser pulses can be generated, light frequency conversion techniques are still indispensable in filling the gaps on the ultrafast spectral scale. With high repetition rate, low pulse energy laser sources (oscillators) tight focusing is necessary for a robust wave mixing and the efficiency of broadband nonlinear conversion is limited by diffraction as well as spatial and temporal walk-off. Here we demonstrate a miniature third harmonic generator (tripler) with conversion efficiency exceeding 30%, producing 246 fs UV pulses via cascaded second order processes within a single laser beam focus. Designing this highly efficient and ultra compact frequency converter was made possible by full 3-dimentional modelling of propagation of tightly focused, broadband light fields in nonlinear and birefringent media. PMID:28225007

  9. Full 3D modelling of pulse propagation enables efficient nonlinear frequency conversion with low energy laser pulses in a single-element tripler

    NASA Astrophysics Data System (ADS)

    Kardaś, Tomasz M.; Nejbauer, Michał; Wnuk, Paweł; Resan, Bojan; Radzewicz, Czesław; Wasylczyk, Piotr

    2017-02-01

    Although new optical materials continue to open up access to more and more wavelength bands where femtosecond laser pulses can be generated, light frequency conversion techniques are still indispensable in filling the gaps on the ultrafast spectral scale. With high repetition rate, low pulse energy laser sources (oscillators) tight focusing is necessary for a robust wave mixing and the efficiency of broadband nonlinear conversion is limited by diffraction as well as spatial and temporal walk-off. Here we demonstrate a miniature third harmonic generator (tripler) with conversion efficiency exceeding 30%, producing 246 fs UV pulses via cascaded second order processes within a single laser beam focus. Designing this highly efficient and ultra compact frequency converter was made possible by full 3-dimentional modelling of propagation of tightly focused, broadband light fields in nonlinear and birefringent media.

  10. Growth and study of nonlinear optical materials for frequency conversion devices with applications in defence and security

    NASA Astrophysics Data System (ADS)

    Tassev, V.; Snure, M.; Vangala, S.; Kimani, M.; Peterson, R.; Schunemann, P.

    2014-10-01

    A series of nonlinear materials including GaAs, GaP, and ZnSe have been examined to determine their suitability for non-linear frequency conversion devices (FCD) and more specifically their use as high power, compact and broadly tunable IR and THz sources for defense and security applications. The more mature GaAs was investigated to reveal the causes for the optical losses that restrict achievement of higher conversion efficiency in quasi-phasematched FCD, while the efforts with GaP were oriented in developing simple, cost effective techniques for fabrication of orientation patterned (OP) templates and optimizing the subsequent thick HVPE growth on these templates. Thus, average growth rates of 50- 70 μm/h were achieved in up to 8-hour long experiments. High optical layer quality was achieved by suitable control of the process parameters. The optimal orientation of the pattern was determined and used as essential feedback aiming to improve the template preparation. This led to the production of the first 300-400 μm thick device quality OPGaP. Efforts to suppress the parasitic nucleation during growths with longer duration or to achieve thicker layers by a 2 step growth process were also made. The main challenge with the newer candidate, OPZnSe, was to establish suitable regimes for hydrothermal growth on plain (001) ZnSe seeds grown by chemical vapor deposition. Two different temperature ranges, 330-350 °C and 290-330 °C, were investigated. The mineralized concentration was also manipulated to accelerate the growth in (111) direction and, thus, to improve the growth in (001) direction. The next material in the line is GaN. The traditional HVPE approach will be combined with a growth at low reactor pressure. Growths will be performed in the next sequence: growth on thin GaN layers grown by MOCVD on sapphire wafers, growth on half-patterned GaN templates with different orientations and, finally, growth on OPGaN templates.

  11. Effective index numerical modelling of microstructured chalcogenide-glass fiber for frequency conversion to the mid-infrared band

    NASA Astrophysics Data System (ADS)

    Bourdon, Pierre; Durécu, Anne; Alhenc-Gelas, Claire; Di Bianca, Laura; Canat, Guillaume; Druon, Frédéric

    2013-02-01

    Chalcogenide glass fibers offer broad transparency range up to the mid-infrared and high nonlinear coefficients making them excellent candidates for four wave mixing frequency conversion. However, the use of microstructured airchalcogenide fibers is mandatory to achieve phase-matching in such a fiber. Numerical modelling of the phase matching condition can be done using the simplified effective index model, initially developed and extensively used to design airsilica fibers. In this paper, we investigate the use of the effective index model in the case of microstructured As2S3 and As2Se3 fibers. One essential step in the method is to evaluate the core radius of a step-index fiber equivalent to the microstructured fiber. Using accurate reference results provided by finite-element computation, we compare the different formulae of the effective core radius proposed in the literature and validated for air-silica fibers. As expected, some discrepancies are observed, especially for the highest wavelengths. We propose new coefficients for these formulae so that the effective index method can be used for numerical modelling of propagation in air-chalcogenide fibers up to 5 μm wavelength. We derive a new formula providing both high accuracy of the effective core radius estimate whatever the microstucture geometry and wavelength, as well as uniqueness of its set of coefficients. This analysis reveals that the value of the effective core radius in the effective index model is only dependent on the microstructure geometry, not on the fiber material. Thus, it can be used for air-silica or air-chalcogenide fibers indifferently.

  12. Homo and heteroepitaxial growth and study of orientation-patterned GaP for nonlinear frequency conversion devices

    NASA Astrophysics Data System (ADS)

    Tassev, V. L.; Vangala, S.; Peterson, R.; Kimani, M.; Snure, M.; Markov, I.

    2016-03-01

    Frequency conversion in orientation-patterned quasi-phase matched materials is a leading approach for generating tunable mid- and long-wave coherent IR radiation for a wide variety of applications. A number of nonlinear optical materials are currently under intensive investigation. Due to their unique properties, chiefly wide IR transparency and high nonlinear susceptibility, GaAs and GaP are among the most promising. Compared to GaAs, GaP has the advantage of having higher thermal conductivity and significantly lower 2PA in the convenient pumping range of 1- 1.7 μm. HVPE growth of OPGaP, however, has encountered certain challenges: low quality and high price of commercially available GaP wafers; and strong parasitic nucleation during HVPE growth that reduces growth rate and aggravates layer quality, often leading to pattern overgrowth. Lessons learned from growing OPGaAs were not entirely helpful, leaving us to alternative solutions for both homoepitaxial growth and template preparation. We report repeatable one-step HVPE growth of up to 400 μm thick OPGaP with excellent domain fidelity deposited for first time on OPGaAs templates. The templates were prepared by wafer fusion bonding or MBE assisted polarity inversion technique. A close to equilibrium growth at such a large lattice mismatch (-3.6%) is itself noteworthy, especially when previously reported attempts (growth of OPZnSe on OPGaAs templates) at much smaller mismatch (+0.3%) have produced limited results. Combining the advantages of the two most promising materials, GaAs and GaP, is a solution that will accelerate the development of high power, tunable laser sources for the mid- and long-wave IR, and THz region.

  13. Method of all-optical frequency encoded decimal to binary and binary coded decimal, binary to gray, and gray to binary data conversion using semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Garai, Sisir Kumar

    2011-07-01

    Conversion of optical data from decimal to binary format is very important in optical computing and optical signal processing. There are many binary code systems to represent decimal numbers, the most common being the binary coded decimal (BCD) and gray code system. There are a wide choice of BCD codes, one of which is a natural BCD having a weighted code of 8421, by means of which it is possible to represent a decimal number from 0 to 9 with a combination of 4bit binary digits. The reflected binary code, also known as the Gray code, is a binary numeral system where two successive values differ in only 1bit. The Gray code is very important in digital optical communication as it is used to prevent spurious output from optical switches as well as to facilitate error correction in digital communications in an optical domain. Here in this communication, the author proposes an all-optical frequency encoded method of ``:decimal to binary, BCD,'' ``binary to gray,'' and ``gray to binary'' data conversion using the high-speed switching actions of semiconductor optical amplifiers. To convert decimal numbers to a binary form, a frequency encoding technique is adopted to represent two binary bits, 0 and 1. The frequency encoding technique offers advantages over conventional encoding techniques in terms of less probability of bit errors and greater reliability. Here the author has exploited the polarization switch made of a semiconductor optical amplifier (SOA) and a property of nonlinear rotation of the state of polarization of the probe beam in SOA for frequency conversion to develop the method of frequency encoded data conversion.

  14. Two-photon interference using background-free quantum frequency conversion of single photons emitted by an InAs quantum dot.

    PubMed

    Ates, Serkan; Agha, Imad; Gulinatti, Angelo; Rech, Ivan; Rakher, Matthew T; Badolato, Antonio; Srinivasan, Kartik

    2012-10-05

    We show that quantum frequency conversion (QFC) can overcome the spectral distinguishability common to inhomogeneously broadened solid-state quantum emitters. QFC is implemented by combining single photons from an InAs/GaAs quantum dot (QD) at 980 nm with a 1550 nm pump laser in a periodically poled lithium niobate (PPLN) waveguide to generate photons at 600 nm with a signal-to-background ratio exceeding 100:1. Photon correlation and two-photon interference measurements confirm that both the single photon character and wave packet interference of individual QD states are preserved during frequency conversion. Finally, we convert two spectrally separate QD transitions to the same wavelength in a single PPLN waveguide and show that the resulting field exhibits nonclassical two-photon interference.

  15. Nonlinear frequency up-conversion of femtosecond pulses from an erbium fibre laser to the range of 0.8 - 1 {mu}m in silica fibres

    SciTech Connect

    Anashkina, E A; Andrianov, A V; Kim, A V

    2013-03-31

    We consider different mechanisms of nonlinear frequency up-conversion of femtosecond pulses emitted by an erbium fibre system ({lambda} = 1.5 {mu}m) to the range of 0.8 - 1.2 {mu}m in nonlinear silica fibres. The generation efficiency and the centre frequencies of dispersive waves are found as functions of the parameters of the fibre and the input pulse. Simple analytical estimates are obtained for the spectral distribution of the intensity and the frequency shift of a wave packet in the region of normal dispersion during the emission of a high-order soliton under phase matching conditions. In the geometrical optics approximation the frequency shifts are estimated in the interaction of dispersive waves with solitons in various regimes. (extreme light fields and their applications)

  16. A batch-fabricated electret-biased wideband MEMS vibration energy harvester with frequency-up conversion behavior powering a UHF wireless sensor node

    NASA Astrophysics Data System (ADS)

    Lu, Y.; O'Riordan, E.; Cottone, F.; Boisseau, S.; Galayko, D.; Blokhina, E.; Marty, F.; Basset, P.

    2016-12-01

    This paper reports a batch-fabricated, low-frequency and wideband MEMS electrostatic vibration energy harvester (e-VEH), which implements corona-charged vertical electrets and nonlinear elastic stoppers. A numeric model is used to perform parametric study, where we observe a wideband bi-modality resulting from nonlinearity. The nonlinear stoppers improve the bandwidth and induce a frequency-up feature at low frequencies. When the e-VEH works with a bias of 45 V, the power reaches a maximum value of 6.6 μW at 428 Hz and 2.0 g rms, and is above 1 μW at 50 Hz. When the frequency drops below 60 Hz, a ‘frequency-up’ conversion behavior is observed with peaks of power at 34 Hz and 52 Hz. The  -3 dB bandwidth is more than 60% of its central frequency, both including and excluding the hysteresis introduced by the nonlinear stoppers. We also perform experiments with wideband Gaussian noise. The device is eventually tested with an RF data transmission setup, where a communication node with an internal temperature sensor is powered. Every 2 min, a data transmission at 868 MHz is performed by the sensor node supplied by the e-VEH, and received at a distance of up to 15 m.

  17. The Mercury Laser System: An Average power, gas-cooled, Yb:S-FAP based system with frequency conversion and wavefront correction

    SciTech Connect

    Bibeau, C; Bayramian, A; Armstrong, P; Ault, E; Beach, R; Benapfl, M; Campbell, R; Dawson, J; Ebbers, C; Freitas, B; Kent, R; Liao, Z; Ladran, T; Menapace, J; Molander, B; Moses, E; Oberhelman, S; Payne, S; Peterson, N; Schaffers, K; Stolz, C; Sutton, S; Tassano, J; Telford, S; Utterback, E; Randles, M

    2005-08-31

    We report on the operation of the Mercury laser with fourteen 4 x 6 cm{sup 2} Yb:S-FAP amplifier slabs pumped by eight 100 kW peak power diode arrays. The system was continuously run at 55 J and 10 Hz for several hours, (2 x 10{sup 5} cumulative shots) with over 80% of the energy in a 6 times diffraction limited spot at 1.047 um. Improved optical quality was achieved in Yb:S-FAP amplifiers with magneto-rheological finishing, a deterministic polishing method. In addition, average power frequency conversion employing YCOB was demonstrated at 50% conversion efficiency or 22.6 J at 10 Hz.

  18. Real-time terahertz wave imaging by nonlinear optical frequency up-conversion in a 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal

    NASA Astrophysics Data System (ADS)

    Fan, Shuzhen; Qi, Feng; Notake, Takashi; Nawata, Kouji; Matsukawa, Takeshi; Takida, Yuma; Minamide, Hiroaki

    2014-03-01

    Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and arts. In this letter, we report on real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal. The active projection-imaging system consisted of (1) THz wave generation, (2) THz-near-infrared hybrid optics, (3) THz wave up-conversion, and (4) an InGaAs camera working at 60 frames per second. The pumping laser system consisted of two optical parametric oscillators pumped by a nano-second frequency-doubled Nd:YAG laser. THz-wave images of handmade samples at 19.3 THz were taken, and videos of a sample moving and a ruler stuck with a black polyethylene film moving were supplied online to show real-time ability. Thanks to the high speed and high responsivity of this technology, real-time THz imaging with a higher signal-to-noise ratio than a commercially available THz micro-bolometer camera was proven to be feasible. By changing the phase-matching condition, i.e., by changing the wavelength of the pumping laser, we suggest THz imaging with a narrow THz frequency band of interest in a wide range from approximately 2 to 30 THz is possible.

  19. Generating Periodic Terahertz Structures in a Relativistic Electron Beam through Frequency Down-Conversion of Optical Lasers

    SciTech Connect

    Dunning, Michael

    2012-07-19

    We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow-band THz sources.

  20. Optical frequency up-conversion by supercontinuum-free widely-tunable fiber-optic Cherenkov radiation

    PubMed Central

    Tu, Haohua; Boppart, Stephen A.

    2010-01-01

    Spectrally-isolated narrowband Cherenkov radiation from commercial nonlinear photonic crystal fibers is demonstrated as an ultrafast optical source with a visible tuning range of 485–690 nm, which complementarily extends the near-infrared tuning range of 690–1020 nm from the corresponding femtosecond Ti:sapphire pump laser. Pump-to-signal conversion efficiency routinely surpasses 10%, enabling multimilliwatt visible output across the entire tuning range. Appropriate selection of fiber parameters and pumping conditions efficiently suppresses the supercontinuum generation typically associated with Cherenkov radiation. PMID:19506636

  1. Frequency dispersion reduction and bond conversion on n-type GaAs by in situ surface oxide removal and passivation

    NASA Astrophysics Data System (ADS)

    Hinkle, C. L.; Sonnet, A. M.; Vogel, E. M.; McDonnell, S.; Hughes, G. J.; Milojevic, M.; Lee, B.; Aguirre-Tostado, F. S.; Choi, K. J.; Kim, J.; Wallace, R. M.

    2007-10-01

    The method of surface preparation on n-type GaAs, even with the presence of an amorphous-Si interfacial passivation layer, is shown to be a critical step in the removal of accumulation capacitance frequency dispersion. In situ deposition and analysis techniques were used to study different surface preparations, including NH4OH, Si-flux, and atomic hydrogen exposures, as well as Si passivation depositions prior to in situ atomic layer deposition of Al2O3. As-O bonding was removed and a bond conversion process with Si deposition is observed. The accumulation capacitance frequency dispersion was removed only when a Si interlayer and a specific surface clean were combined.

  2. High-frequency conversion to a "fluffy" developmental phenotype in Aspergillus spp. by 5-azacytidine treatment: evidence for involvement of a single nuclear gene.

    PubMed Central

    Tamame, M; Antequera, F; Villanueva, J R; Santos, T

    1983-01-01

    Transient exposure of mycelia from Aspergillus niger and Aspergillus nidulans to the cytidine analog 5-azacytidine, leading to no more than 0.3 to 0.5% substitution for cytosine by 5-azacytosine in A. nidulans DNA, resulted in the conversion of a high fraction of the cell population (more than 20%) to a mitotically and meiotically stable "fluffy" developmental phenotype. The phenotypic variants are characterized by the developmentally timed production of a profuse fluffy network of undifferentiated aerial hyphae that seem to escape signals governing vegetative growth. Genetic analysis with six different fluffy clones reveals that this trait is not cytoplasmically coded, is recessive in heterozygous diploids but codominant in heterokaryons, and exhibits a 1:1 Mendelian segregation pattern upon sexual sporulation of heterozygous diploids. Complementation and mitotic haploidization studies indicated that all variants are affected in the same gene, which can be tentatively located on chromosome VIII of A. nidulans. Molecular analysis to search for modified bases showed that DNA methylation is negligible in in both A. niger and A. nidulans and that no differences could be detected among DNAs from wild-type cells, fluffy clones, or mycelia exposed to 5-azacytidine. It thus appears that high-frequency conversion of fungal mycelia to a stable, variant developmental phenotype by 5-azacytidine is the result of some kind of target action on a single nuclear gene and that this conversion can occur in organisms virtually devoid of DNA methylation. Images PMID:6197627

  3. Growth and Study of Nonlinear Optical Materials for Frequency Conversion Devices with Applications in Defense and Security

    DTIC Science & Technology

    2015-03-01

    in science (IR and THz spectroscopy) and in medicine ( medical images, biopsy-free cancer cell detection). One would be amazed by the great number...of laser sources (http://en.wikipedia.org/ wiki /List_of_laser-types) developed since 1960 when Theodore Maiman demonstrated at Hughes Research Labs...frequency ranges: Figure 1. Current laser sources available in the IR and THz (http://en.wikipedia.org/ wiki /Infrared_lasers). At first

  4. Measuring solid-state quantum yields: The conversion of a frequency-doubled Nd:YAG diode laser pointer module into a viable light source.

    PubMed

    Daglen, Bevin C; Harris, John D; Dax, Clifford D; Tyler, David R

    2007-07-01

    This article outlines the difficulties associated with measuring quantum yields for solid-state samples using a high-pressure mercury arc lamp as the irradiation source. Details are given for the conversion of an inexpensive frequency-doubled neodymium-doped yttrium aluminum garnet (Nd:YAG) diode laser pointer module into a viable irradiation source. The modified Nd:YAG laser was incorporated into a computer-controlled system, which allowed for the simultaneous irradiation and spectroscopic monitoring of the sample. The data obtained with the Nd:YAG diode laser system show far less scatter than data obtained with a high-pressure Hg arc lamp, and consequently the degradation rates obtained with the laser system could be calculated with far greater accuracy.

  5. Validation of full-wave simulations for mode conversion of waves in the ion cyclotron range of frequencies with phase contrast imaging in Alcator C-Mod

    SciTech Connect

    Tsujii, N.; Porkolab, M.; Bonoli, P. T.; Edlund, E. M.; Ennever, P. C.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Jaeger, E. F.; Green, D. L.; Harvey, R. W.

    2015-08-15

    Mode conversion of fast waves in the ion cyclotron range of frequencies (ICRF) is known to result in current drive and flow drive under optimised conditions, which may be utilized to control plasma profiles and improve fusion plasma performance. To describe these processes accurately in a realistic toroidal geometry, numerical simulations are essential. Quantitative comparison of these simulations and the actual experimental measurements is important to validate their predictions and to evaluate their limitations. The phase contrast imaging (PCI) diagnostic has been used to directly detect the ICRF waves in the Alcator C-Mod tokamak. The measurements have been compared with full-wave simulations through a synthetic diagnostic technique. Recently, the frequency response of the PCI detector array on Alcator C-Mod was recalibrated, which greatly improved the comparison between the measurements and the simulations. In this study, mode converted waves for D-{sup 3}He and D-H plasmas with various ion species compositions were re-analyzed with the new calibration. For the minority heating cases, self-consistent electric fields and a minority ion distribution function were simulated by iterating a full-wave code and a Fokker-Planck code. The simulated mode converted wave intensity was in quite reasonable agreement with the measurements close to the antenna, but discrepancies remain for comparison at larger distances.

  6. Tunable error-free optical frequency conversion of a 4ps optical short pulse over 25 nm by four-wave mixing in a polarisation-maintaining optical fibre

    NASA Astrophysics Data System (ADS)

    Morioka, T.; Kawanishi, S.; Saruwatari, M.

    1994-05-01

    Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signalis demonstrated at 6.3 Gbit/s using four-wave mixing in a polarization-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB.

  7. Frequency mixer having ferromagnetic film

    DOEpatents

    Khitun, Alexander; Roshchin, Igor V.; Galatsis, Kosmas; Bao, Mingqiang; Wang, Kang L.

    2016-03-29

    A frequency conversion device, which may include a radiofrequency (RF) mixer device, includes a substrate and a ferromagnetic film disposed over a surface of the substrate. An insulator is disposed over the ferromagnetic film and at least one microstrip antenna is disposed over the insulator. The ferromagnetic film provides a non-linear response to the frequency conversion device. The frequency conversion device may be used for signal mixing and amplification. The frequency conversion device may also be used in data encryption applications.

  8. High-power continuous-wave Raman frequency conversion from 1.06 µm to 1.49 µm in diamond.

    PubMed

    Williams, Robert J; Spence, David J; Lux, Oliver; Mildren, Richard P

    2017-01-23

    We report continuous-wave beam conversion from 1.06 to 1.49 µm in a diamond Raman laser operating on the second Stokes shift. High power (114 W) and high conversion efficiency (44%) is achieved using a single cavity that is highly resonant at the first Stokes wavelength but has high output coupling at the second Stokes wavelength (89%). An analytical model was developed for external-cavity Raman lasers operating in steady-state, revealing that optimization of second Stokes output is markedly different to first Stokes and that there is a direct and proportional relationship between the second Stokes output coupling and the pump depletion in the diamond, which we have confirmed by experiment. This technology shows promise for power scaling beyond the capabilities of current fiber lasers operating in the applications-rich 1.5-1.6 µm wavelength range.

  9. Frequency up-conversion in nonpolar a-plane GaN/AlGaN based multiple quantum wells optimized for applications with silicon solar cells

    SciTech Connect

    Radosavljević, S.; Radovanović, J. Milanović, V.; Tomić, S.

    2014-07-21

    We have described a method for structural parameters optimization of GaN/AlGaN multiple quantum well based up-converter for silicon solar cells. It involves a systematic tuning of individual step quantum wells by use of the genetic algorithm for global optimization. In quantum well structures, the up-conversion process can be achieved by utilizing nonlinear optical effects based on intersubband transitions. Both single and double step quantum wells have been tested in order to maximize the second order susceptibility derived from the density matrix formalism. The results obtained for single step wells proved slightly better and have been further pursued to obtain a more complex design, optimized for conversion of an entire range of incident photon energies.

  10. Control of the photoelectron dynamics for the effective conversion of short-pulse, frequency-modulated optical radiation into X-ray radiation

    SciTech Connect

    Silaev, A A; Meshkov, O V; Emelin, M Yu; Vvedenskii, N V; Ryabikin, M Yu

    2015-05-31

    We report a theoretical investigation of high-order harmonic generation (HHG) in the ionisation of atoms by nonlinear frequency-modulated laser pulses of short duration. It is shown that the reduction in the instantaneous value of the laser pulse frequency can lead to a significant increase in the width of the plateau in the HHG spectrum. We have found optimal parameters of frequency modulation at which photons with energies of 1 keV are efficiently generated at a relatively low laser-pulse intensity. High HHG efficiency at optimal parameters is explained by the peculiarities of atomic ionisation dynamics and acceleration of photoelectrons by a frequency-modulated laser field. (extreme light fields and their applications)

  11. Origin of Noise in AlGaN/GaN Heterostructures in the Range of 1Hz-100 MHz and its Up-Conversion in High-Frequency Noise of Oscillators

    NASA Astrophysics Data System (ADS)

    Vitusevich, S. A.

    2007-07-01

    This paper gives an overview of our recently obtained results on investigation of noise properties in undoped AlGaN/GaN high electron mobility transistors for the development of low-noise oscillators. The features observed in the carrier transport and noise spectra in two-dimensional AlGaN/GaN conducting channels grown on sapphire substrate are explained on the basis of a model taking into account the overheating effect and dynamic redistribution of potential. The low-frequency noise investigation of AlGaN/GaN heterostructures grown on SiC substrate showed that passivation significantly decreased the level of channel noise, but the noise coming from contact regions was found to be dominant in passivated devices. For the frequency range of 10-100 MHz in the structures, the fluctuations of electron concentration on the first quantum level of the quantum well and the scattering of the electrons in the barrier have been established. The measured phase noise of the oscillator shows that the low-frequency noise of the microwave active device is up-converted into phase fluctuations of the high-frequency carrier. The up-conversion factor of the oscillator for an offset frequency of 100 kHz is only about 15 kHz/V, which results in very low oscillator phase noise of - 105 dBc/Hz.

  12. Digital optical conversion module

    DOEpatents

    Kotter, Dale K.; Rankin, Richard A.

    1991-02-26

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

  13. Digital optical conversion module

    DOEpatents

    Kotter, D.K.; Rankin, R.A.

    1988-07-19

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer. 2 figs.

  14. Matched cascade of bandgap-shift and frequency-conversion using stimulated Raman scattering in a tapered hollow-core photonic crystal fibre.

    PubMed

    Beaudou, B; Couny, F; Wang, Y Y; Light, P S; Wheeler, N V; Gérôme, F; Benabid, F

    2010-06-07

    We report on a novel means which lifts the restriction of the limited optical bandwidth of photonic bandgap hollow-core photonic crystal fiber on generating high order stimulated Raman scattering in gaseous media. This is based on H(2)-filled tapered HC-PCF in which the taper slope is matched with the effective length of Raman process. Raman orders outside the input-bandwidth of the HC-PCF are observed with more than 80% quantum-conversion using a compact, low-power 1064 nm microchip laser. The technique opens prospects for efficient sources in spectral regions that are poorly covered by currently existing lasers such as mid-IR.

  15. Contentious Conversations

    ERIC Educational Resources Information Center

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  16. Metric Conversion

    Atmospheric Science Data Center

    2013-03-12

    ... petabyte = one quadrillion bytes The Bureau International Poids et Measures (BIPM) brochure on the International System ... For accurate conversions, see the National Institute of Standards and Technology (NIST) Special Publications: NIST Guide to ...

  17. Conversion Disorder

    MedlinePlus

    ... Recent significant stress or emotional trauma Being female — women are much more likely to develop conversion disorder Having a mental health condition, such as mood or anxiety disorders, dissociative disorder or certain personality disorders Having ...

  18. High resolution A/D conversion based on piecewise conversion at lower resolution

    DOEpatents

    Terwilliger, Steve [Albuquerque, NM

    2012-06-05

    Piecewise conversion of an analog input signal is performed utilizing a plurality of relatively lower bit resolution A/D conversions. The results of this piecewise conversion are interpreted to achieve a relatively higher bit resolution A/D conversion without sampling frequency penalty.

  19. Simultaneous clock recovery and dispersion, OSNR monitoring for 112-Gbit/s NRZ-DQPSK using frequency down-conversion electro-optical phase-locked loop.

    PubMed

    Wen, He; Cheng, Lin; Liao, Jinxin; Zheng, Xiaoping; Zhang, Hanyi; Guo, Yili; Zhou, Bingkun

    2011-12-12

    A cost effective clock recovery scheme simultaneously providing signal performance monitoring is proposed for high speed electrical time domain multiplexing (ETDM) transmission systems to release the bandwidth requirement on the involved electrical devices. In the scheme, we first convert the clock frequency down in the optical domain using electroptic modulation, and then extract the clock with a phase locked loop (PLL) after photo-detection. All the devices involved are operated at frequencies lower than half of the symbol rate. Furthermore, we use a quadrature phase detector in the PLL to create a monitor signal which characterizes the transmitted signal performance in terms of optical-to-noise ratio (OSNR) and accumulated chromatic dispersion (ACD). This scheme is applied to a 112-Gbit/s none-return-to-zero (NRZ) differential quadrature phase shift keying (DQPSK) system. Experimental results show that the clock can be recovered in a dispersion range of -40 to 40 ps/nm, and the evaluated OSNR, over a range of 18~36 dB, has a deviation smaller than 1 dB compared to the measured one based on the optical spectrum method. The bit error ratio remains below 10(-9) for 12 hours in the back-to-back case and 2 hours after transmission over 100-km standard single mode fiber (SSMF).

  20. Conversational Telugu.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop elementary conversational skills in Telugu. The language materials consist of four types of language learning activities. The first, and most predominant, is the unit microwave cycle. These cycles divide the learning process into two basic phases, the first of which involves mimicry, memorization, and…

  1. Conversational Tamil.

    ERIC Educational Resources Information Center

    Beinstein, Judith; And Others

    The purpose of this text is to develop conversational skills in Tamil. It is to be used as a review of what has been learned in class and not as a teaching device. The language materials consist of four types of language learning activities. The unit microwave cycle divides the learning process into two basic phases. The first phase involves…

  2. Conversational sensing

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  3. Conversational sensemaking

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Webberley, Will; Braines, Dave

    2015-05-01

    Recent advances in natural language question-answering systems and context-aware mobile apps create opportunities for improved sensemaking in a tactical setting. Users equipped with mobile devices act as both sensors (able to acquire information) and effectors (able to act in situ), operating alone or in collectives. The currently- dominant technical approaches follow either a pull model (e.g. Apple's Siri or IBM's Watson which respond to users' natural language queries) or a push model (e.g. Google's Now which sends notifications to a user based on their context). There is growing recognition that users need more flexible styles of conversational interaction, where they are able to freely ask or tell, be asked or told, seek explanations and clarifications. Ideally such conversations should involve a mix of human and machine agents, able to collaborate in collective sensemaking activities with as few barriers as possible. Desirable capabilities include adding new knowledge, collaboratively building models, invoking specific services, and drawing inferences. As a step towards this goal, we collect evidence from a number of recent pilot studies including natural experiments (e.g. situation awareness in the context of organised protests) and synthetic experiments (e.g. human and machine agents collaborating in information seeking and spot reporting). We identify some principles and areas of future research for "conversational sensemaking".

  4. Frequency conversion in compositionally graded PPLN crystals

    SciTech Connect

    Galutskiy, V V; Stroganova, E V; Shmargilov, S A; Yakovenko, N A

    2014-01-31

    This paper considers the effect of the longitudinal lithium concentration distribution in PPLN converters on their efficiency in high-power cw laser second harmonic generation. (nonlinear optical phenomena)

  5. Frequency-controlled voltage regulator

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1980-01-01

    Converting input ac to higher frequency reduce size and weight and makes possible unique kind of regulation. Since conversion frequency is above range of human hearing, supply generated on audible noise. It also exploits highfrequency conversion features to regulate its output voltage in novel way. Circuit is inherently short-circuit proof.

  6. Mode conversion heating experiments on Tore Supra

    SciTech Connect

    Saoutic, B.; Becoulet, A.; Hutter, T.; Fraboulet, D.; Ram, A.K.; Bers, A.

    1996-02-01

    A new scenario for effeicient mode conversion heating, in the ion cyclotron range of frequency, is proposed. Experiments on Tore Supra demonstrate that this new scheme is quite efficient. A detailed analysis of thes mode conversion scenario is carried out, using a new complete 1-D model and the 3-D full wave code Alcyon. {copyright} {ital 1996 American Institute of Physics.}

  7. Mode conversion heating experiments on Tore Supra

    NASA Astrophysics Data System (ADS)

    Saoutic, B.; Bécoulet, A.; Hutter, T.; Fraboulet, D.; Ram, A. K.; Bers, A.

    1996-02-01

    A new scenario for effeicient mode conversion heating, in the ion cyclotron range of frequency, is proposed. Experiments on Tore Supra demonstrate that this new scheme is quite efficient. A detailed analysis of thes mode conversion scenario is carried out, using a new complete 1-D model and the 3-D full wave code Alcyon.

  8. Conversion of Questionnaire Data

    SciTech Connect

    Powell, Danny H; Elwood Jr, Robert H

    2011-01-01

    During the survey, respondents are asked to provide qualitative answers (well, adequate, needs improvement) on how well material control and accountability (MC&A) functions are being performed. These responses can be used to develop failure probabilities for basic events performed during routine operation of the MC&A systems. The failure frequencies for individual events may be used to estimate total system effectiveness using a fault tree in a probabilistic risk analysis (PRA). Numeric risk values are required for the PRA fault tree calculations that are performed to evaluate system effectiveness. So, the performance ratings in the questionnaire must be converted to relative risk values for all of the basic MC&A tasks performed in the facility. If a specific material protection, control, and accountability (MPC&A) task is being performed at the 'perfect' level, the task is considered to have a near zero risk of failure. If the task is performed at a less than perfect level, the deficiency in performance represents some risk of failure for the event. As the degree of deficiency in performance increases, the risk of failure increases. If a task that should be performed is not being performed, that task is in a state of failure. The failure probabilities of all basic events contribute to the total system risk. Conversion of questionnaire MPC&A system performance data to numeric values is a separate function from the process of completing the questionnaire. When specific questions in the questionnaire are answered, the focus is on correctly assessing and reporting, in an adjectival manner, the actual performance of the related MC&A function. Prior to conversion, consideration should not be given to the numeric value that will be assigned during the conversion process. In the conversion process, adjectival responses to questions on system performance are quantified based on a log normal scale typically used in human error analysis (see A.D. Swain and H.E. Guttmann

  9. Mode conversion in ITER

    NASA Astrophysics Data System (ADS)

    Jaeger, E. F.; Berry, L. A.; Myra, J. R.

    2006-10-01

    Fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) can convert to much shorter wavelength modes such as ion Bernstein waves (IBW) and ion cyclotron waves (ICW) [1]. These modes are potentially useful for plasma control through the generation of localized currents and sheared flows. As part of the SciDAC Center for Simulation of Wave-Plasma Interactions project, the AORSA global-wave solver [2] has been ported to the new, dual-core Cray XT-3 (Jaguar) at ORNL where it demonstrates excellent scaling with the number of processors. Preliminary calculations using 4096 processors have allowed the first full-wave simulations of mode conversion in ITER. Mode conversion from the fast wave to the ICW is observed in mixtures of deuterium, tritium and helium3 at 53 MHz. The resulting flow velocity and electric field shear will be calculated. [1] F.W. Perkins, Nucl. Fusion 17, 1197 (1977). [2] E.F. Jaeger, L.A. Berry, J.R. Myra, et al., Phys. Rev. Lett. 90, 195001-1 (2003).

  10. Pashto Conversation Manual and Pashto Conversation Tapescript.

    ERIC Educational Resources Information Center

    Tegey, Habibullah; Robson, Barbara

    This conversation manual and tapescript are part of a set of materials that have been developed to teach oral and written Afghan Pashto to English speakers. In addition to the conversation manual and tapescript, the set consists of a beginning textbook, an intermediate textbook, a reader, and a set of taped lessons that correlate with the…

  11. Inequivalence of direct and converse magnetoelectric coupling at electromechanical resonance

    NASA Astrophysics Data System (ADS)

    Wu, Gaojian; Nan, Tianxiang; Zhang, Ru; Zhang, Ning; Li, Shandong; Sun, Nian X.

    2013-10-01

    Resonant direct and converse magnetoelectric (ME) effects have been investigated experimentally and theoretically in FeGa/PZT/FeGa sandwich laminate composites under the same electric and magnetic bias conditions. Resonant direct ME effect (DME) occurs at antiresonance frequency while resonant converse ME effect (CME) occurs at resonance frequency. The antiresonance and resonance frequencies have close but different values under identical bias conditions. The magnitudes of resonant effective ME coefficients for direct and converse ME effects are also not equal. A model was developed to describe the frequency response of DME and CME in laminate composite, which was in good agreement with experimental results.

  12. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  13. Learning through Conversation.

    ERIC Educational Resources Information Center

    Kelly, Patricia R.; Klein, Adria F.; Pinnell, Gay Su

    1996-01-01

    Through teacher-child conversation, experts use oral language to help novices take on more complex tasks; and Reading Recovery children, who are obviously having difficulty with school-based learning, are especially in need of significant conversations with adults. Reading and writing processes are supported through conversation with Reading…

  14. NGL data conversion system

    NASA Astrophysics Data System (ADS)

    Shoji, Masahiro; Horiuchi, Nobuyasu

    2005-06-01

    We are developing a NGL data conversion system for EPL, for LEEPL, and for EBDW, which is based on our established photomask data conversion system, PATACON PC-cluster. For EPL data conversion, it has SF division, Complementary division, Stitching, Proximity effect correction, Alignment mark insertion, EB stepper control data creation, and Mask inspection data creation. For LEEPL data conversion, it has Pattern checking, Complementary division, Stitching, Stress distortion correction, Alignment mark insertion, and Mask inspection data creation. For EB direct-writing data conversion, it has Proximity effect correction and Extraction of aperture pattern for cell projection exposure.

  15. Iterated multidimensional wave conversion

    SciTech Connect

    Brizard, A. J.; Tracy, E. R.; Johnston, D.; Kaufman, A. N.; Richardson, A. S.; Zobin, N.

    2011-12-23

    Mode conversion can occur repeatedly in a two-dimensional cavity (e.g., the poloidal cross section of an axisymmetric tokamak). We report on two novel concepts that allow for a complete and global visualization of the ray evolution under iterated conversions. First, iterated conversion is discussed in terms of ray-induced maps from the two-dimensional conversion surface to itself (which can be visualized in terms of three-dimensional rooms). Second, the two-dimensional conversion surface is shown to possess a symplectic structure derived from Dirac constraints associated with the two dispersion surfaces of the interacting waves.

  16. Conversing with Computers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    I/NET, Inc., is making the dream of natural human-computer conversation a practical reality. Through a combination of advanced artificial intelligence research and practical software design, I/NET has taken the complexity out of developing advanced, natural language interfaces. Conversational capabilities like pronoun resolution, anaphora and ellipsis processing, and dialog management that were once available only in the laboratory can now be brought to any application with any speech recognition system using I/NET s conversational engine middleware.

  17. Polarization conversion in cubic Raman crystals

    NASA Astrophysics Data System (ADS)

    McKay, Aaron; Sabella, Alexander; Mildren, Richard P.

    2017-02-01

    Nonlinear conversion of unpolarized beams to lower frequencies is generally inefficient in c(2) materials, as it is challenging to achieve phase-matching for input ordinary and extraordinary beams simultaneously in the normal dispersion regime. Here, we show that cubic Raman crystals having doubly and triply degenerate (E and F type) modes provide a method for efficient nonlinear frequency downconversion of an unpolarized beam and yield a linearly polarized output state. Using Mueller calculus, optimal crystal directions for such polarization conversion are determined. Using diamond, an example of an F-class Raman crystal, we have verified that such conversion is possible with near quantum-defect-limited slope efficiency and a linear polarization contrast of more than 23.9 dB.

  18. Polarization conversion in cubic Raman crystals

    PubMed Central

    McKay, Aaron; Sabella, Alexander; Mildren, Richard P.

    2017-01-01

    Nonlinear conversion of unpolarized beams to lower frequencies is generally inefficient in c(2) materials, as it is challenging to achieve phase-matching for input ordinary and extraordinary beams simultaneously in the normal dispersion regime. Here, we show that cubic Raman crystals having doubly and triply degenerate (E and F type) modes provide a method for efficient nonlinear frequency downconversion of an unpolarized beam and yield a linearly polarized output state. Using Mueller calculus, optimal crystal directions for such polarization conversion are determined. Using diamond, an example of an F-class Raman crystal, we have verified that such conversion is possible with near quantum-defect-limited slope efficiency and a linear polarization contrast of more than 23.9 dB. PMID:28169327

  19. 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.

  20. Conversations in Child Care

    ERIC Educational Resources Information Center

    Bardige, Betty; Segal, Marilyn

    2004-01-01

    In this article, Bardige and Segal discuss how teachers can help a toddler's language and literacy development through conversation. They suggest an array of tactics, from asking young children open-ended, intellectually challenging questions to going beyond the here and now when carrying on a conversation. Research has shown that the practice of…

  1. Recording Conversations in Schools.

    ERIC Educational Resources Information Center

    Gluckman, Ivan B.; Koerner, Thomas J., Jr.

    1988-01-01

    In general, because of varying federal and state legislation and a paucity of court decisions, the law governing the recording of conversations is in considerable flux. School personnel desiring to record conversations in school without the consent or knowledge of all parties involved must proceed with considerable caution. (Author)

  2. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  3. Assessment through Conversation.

    ERIC Educational Resources Information Center

    Fu, Danling; Lamme, Linda L.

    2002-01-01

    Presents conversations with parents, teachers, and children around portfolios that provide a better picture of a child's growth and understanding than standardized test scores ever can. Concludes that the involvement of students, teachers, and parents in conversation about children's literacy development brings the potential of a common vision and…

  4. NUCLEAR CONVERSION APPARATUS

    DOEpatents

    Seaborg, G.T.

    1960-09-13

    A nuclear conversion apparatus is described which comprises a body of neutron moderator, tubes extending therethrough, uranium in the tubes, a fluid- circulating system associated with the tubes, a thorium-containing fluid coolant in the system and tubes, and means for withdrawing the fluid from the system and replacing it in the system whereby thorium conversion products may be recovered.

  5. Content for Conversation Partners.

    ERIC Educational Resources Information Center

    Olson, Kathleen

    2002-01-01

    Suggests that a good strategy for helping English language learners to develop communicative competence in English is by pairing them with native English speakers. In such conversation programs, conversation partners should be provided with topics and activities that incorporate the goals, interests, and experiences of the learners. Recommends…

  6. Laser radiation frequency conversion in carbon- and cluster-containing plasma plumes under conditions of single and two-color pumping by pulses with a 10-Hz repetition rate

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.

    2013-07-01

    This work reviews a series of investigations of different plasma plumes using single- and two-color laser systems that emit femtosecond pulses with a 10-Hz repetition rate. Results of investigation of the resonant enhancement of harmonics in tin plasma with the use of two types of pumps are analyzed, and it is shown that the tuning of the wavelengths of harmonics to ion-resonance levels plays an important role in increasing the conversion efficiency to high-order harmonics of the radiation to be converted. Investigations of different carbon-containing plasma media (carbon nanotubes, graphite, carbon aerogel, etc.) exhibit attractive properties of the nonlinear medium of this type for efficient generation of high-order harmonics. The results of the first experiments on the use of nanoparticles produced directly in the course of laser ablation of metals for increasing the efficiency of harmonics generated in this cluster-containing medium are analyzed. It is shown that new approaches realized in these investigations give hope that the nonlinear optical response of plasma media in the far-ultraviolet range can be further increased.

  7. Enhanced 2 μm broad-band emission and NIR to visible frequency up-conversion from Ho3+/Yb3+ co-doped Bi2O3-GeO2-ZnO glasses.

    PubMed

    Biswas, Kaushik; Sontakke, Atul D; Sen, R; Annapurna, K

    2013-08-01

    In this work, a new and non-conventional oxide glass composition based on Bi2O3-GeO2-ZnO system has been formulated with an aim to realize low phonon oxide glass and elucidate its performance when co-doped with Ho(3+)/Yb(3+) for the energy transfer based NIR emission at 2 μm from Ho(3+) ions under Yb(3+) excitation. The glass with 1.0 mol% Ho2O3 and 0.5 mol% Yb2O3 has exhibited maximum energy transfer rate (3602 s(-1)) and energy transfer efficiency (65.92%). Important radiative properties have been predicted for emission transitions of Ho(3+) ions using intensity parameters derived from measured absorption spectra using standard Judd-Ofelt theory. At lower acceptor ion concentration (0.1 mol%), an efficient NIR to visible up-conversion emission has been observed based on two photon absorption process which has found to be reduced significantly at higher Ho(3+) concentrations with simultaneous enhancement in 2 μm emission. Hence, this newly developed glass codoped with Yb(3+)/Ho(3+) is promising glass for sensitized 2 μm emission applications as broad band tunable lasers because of the combination of low phonon energy (707 cm(-1)), high energy transfer efficiency, moderately high emission cross-section (5.33×10(-21) cm(2)) and larger effective half-width of the emission band value of 169 nm.

  8. 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.

  9. Metric Conversion Costs in Industrial Education Career Fields

    ERIC Educational Resources Information Center

    Clark, Andrew; Preitz, Clarence

    1976-01-01

    The study investigated metric conversion costs using two mailed instruments to obtain frequency and cost data on equipment and textbook holdings from 39 schools in Alberta. Detailed results indicated an overall conversion cost of $1,000,000 with mechanics and construction-fabrication career fields accounting for most of the total. (Author/MS)

  10. 0.5W CW single frequency blue at 486 nm via SHG with net conversion of 81.5% from the NIR using a 30mm PPMgO:SLT crystal in a resonant cavity

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Jadhav, Shilpa; Shiner, David

    2015-02-01

    A single frequency fiber Bragg grating (FBG) stabilized laser at 972 nm is coupled into a doubling ring cavity with an optical length of 138 mm, a 91% input coupler, a 30 mm long Brewster cut magnesium doped periodically poled lithium tantalate (PPMgO:SLT) crystal and a high reflector. The cavity buildup is 37 and loss is 0.63%. The cavity is monitored, controlled and locked with a single chip processor. With IR power of 572 mW in the input fiber, 466 mW blue output is obtained, giving 81.5% net efficiency. The blue and IR beams are separated by refraction at the crystal's Brewster surface with negligible loss and without the need for dichroic optics.

  11. FET Frequency Discriminator.

    DTIC Science & Technology

    1982-03-01

    conversion . characteristic of the frequency discriminator is significant and :ending upon the specific system - may be the limiting factor in the accu of...the results obtained did not .-" allow for the accurate determinat ion of the change in impedance, addit ional 14 -~ 12V - - Figure 7. Impedance plot...44*. -. 7 ’I -- -..- ,. -, 4., /-.,’ .3 8 V ............... ... .. .$, L- 12v - Figure 9. Impedance plot tor five diodes inl parallel. A circuit was

  12. Solar Thermal Conversion

    SciTech Connect

    Kreith, F.; Meyer, R. T.

    1982-11-01

    The thermal conversion process of solar energy is based on well-known phenomena of heat transfer (Kreith 1976). In all thermal conversion processes, solar radiation is absorbed at the surface of a receiver, which contains or is in contact with flow passages through which a working fluid passes. As the receiver heats up, heat is transferred to the working fluid which may be air, water, oil, or a molten salt. The upper temperature that can be achieved in solar thermal conversion depends on the insolation, the degree to which the sunlight is concentrated, and the measures taken to reduce heat losses from the working fluid.

  13. Postoperative conversion disorder.

    PubMed

    Afolabi, Kola; Ali, Sameer; Gahtan, Vivian; Gorji, Reza; Li, Fenghua; Nussmeier, Nancy A

    2016-05-01

    Conversion disorder is a psychiatric disorder in which psychological stress causes neurologic deficits. A 28-year-old female surgical patient had uneventful general anesthesia and emergence but developed conversion disorder 1 hour postoperatively. She reported difficulty speaking, right-hand numbness and weakness, and right-leg paralysis. Neurologic examination and imaging revealed no neuronal damage, herniation, hemorrhage, or stroke. The patient mentioned failing examinations the day before surgery and discontinuing her prescribed antidepressant medication, leading us to diagnose conversion disorder, with eventual confirmation by neuroimaging and follow-up examinations.

  14. Responsive Teaching through Conversation

    ERIC Educational Resources Information Center

    Dozier, Cheryl; Garnett, Susan; Tabatabai, Simeen

    2011-01-01

    Conversations are the heart of responsive teaching. By talking with struggling learners, teachers can find out about their interests in order to design effective, personalized instruction; build relationships; work through complexities in teaching and learning; and celebrate successes.

  15. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  16. Conversational flow promotes solidarity.

    PubMed

    Koudenburg, Namkje; Postmes, Tom; Gordijn, Ernestine H

    2013-01-01

    Social interaction is fundamental to the development of various aspects of "we-ness". Previous research has focused on the role the content of interaction plays in establishing feelings of unity, belongingness and shared reality (a cluster of variables referred to as solidarity here). The present paper is less concerned with content, but focuses on the form of social interaction. We propose that the degree to which conversations flow smoothly or not is, of itself, a cue to solidarity. We test this hypothesis in samples of unacquainted and acquainted dyads who communicate via headsets. Conversational flow is disrupted by introducing a delay in the auditory feedback (vs. no delay). Results of three studies show that smoothly coordinated conversations (compared with disrupted conversations and a control condition) increase feelings of belonging and perceptions of group entitativity, independently of conversation content. These effects are driven by the subjective experience of conversational flow. Our data suggest that this process occurs largely beyond individuals' control. We conclude that the form of social interaction is a powerful cue for inferring group solidarity. Implications for the impact of modern communication technology on developing a shared social identity are discussed.

  17. Astrophysicists’ Conversational Connections on Twitter

    PubMed Central

    Holmberg, Kim; Bowman, Timothy D.; Haustein, Stefanie; Peters, Isabella

    2014-01-01

    Because Twitter and other social media are increasingly used for analyses based on altmetrics, this research sought to understand what contexts, affordance use, and social activities influence the tweeting behavior of astrophysicists. Thus, the presented study has been guided by three research questions that consider the influence of astrophysicists’ activities (i.e., publishing and tweeting frequency) and of their tweet construction and affordance use (i.e. use of hashtags, language, and emotions) on the conversational connections they have on Twitter. We found that astrophysicists communicate with a variety of user types (e.g. colleagues, science communicators, other researchers, and educators) and that in the ego networks of the astrophysicists clear groups consisting of users with different professional roles can be distinguished. Interestingly, the analysis of noun phrases and hashtags showed that when the astrophysicists address the different groups of very different professional composition they use very similar terminology, but that they do not talk to each other (i.e. mentioning other user names in tweets). The results also showed that in those areas of the ego networks that tweeted more the sentiment of the tweets tended to be closer to neutral, connecting frequent tweeting with information sharing activities rather than conversations or expressing opinions. PMID:25153196

  18. Isomolybdate conversion coatings

    NASA Technical Reports Server (NTRS)

    Minevski, Zoran (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating solution and process forms a stable and corrosion-resistant layer on metal substrates or layers or, more preferably, on a boehmite layer or other base conversion coating. The conversion coating process involves contacting the substrate, layer or coating with an aqueous alkali metal isomolybdate solution in order to convert the surface of the substrate, layer or coating to a stable conversion coating. The aqueous alkali metal molybdates are selected from sodium molybdate (Na.sub.2 MoO.sub.4), lithium molybdate (Li.sub.2 MoO.sub.4), potassium molybdate (K.sub.2 MoO.sub.4), or combinations thereof, with the most preferred alkali metal molybdate being sodium molybdate. The concentration of alkali metal molybdates in the solution is preferably less than 5% by weight. In addition to the alkali metal molybdates, the conversion coating solution may include alkaline metal passivators selected from lithium nitrate (LiNO.sub.3), sodium nitrate (NaNO.sub.3), ammonia nitrate (NH.sub.4 NO.sub.3), and combinations thereof; lithium chloride, potassium hexafluorozirconate (K.sub.2 ZrF.sub.6) or potassium hexafluorotitanate (K.sub.2 TiF.sub.6).

  19. Laser energy conversion

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1989-01-01

    The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.

  20. Predictability of Conversation Partners

    NASA Astrophysics Data System (ADS)

    Takaguchi, Taro; Nakamura, Mitsuhiro; Sato, Nobuo; Yano, Kazuo; Masuda, Naoki

    2011-08-01

    Recent developments in sensing technologies have enabled us to examine the nature of human social behavior in greater detail. By applying an information-theoretic method to the spatiotemporal data of cell-phone locations, [C. Song , ScienceSCIEAS0036-8075 327, 1018 (2010)] found that human mobility patterns are remarkably predictable. Inspired by their work, we address a similar predictability question in a different kind of human social activity: conversation events. The predictability in the sequence of one’s conversation partners is defined as the degree to which one’s next conversation partner can be predicted given the current partner. We quantify this predictability by using the mutual information. We examine the predictability of conversation events for each individual using the longitudinal data of face-to-face interactions collected from two company offices in Japan. Each subject wears a name tag equipped with an infrared sensor node, and conversation events are marked when signals are exchanged between sensor nodes in close proximity. We find that the conversation events are predictable to a certain extent; knowing the current partner decreases the uncertainty about the next partner by 28.4% on average. Much of the predictability is explained by long-tailed distributions of interevent intervals. However, a predictability also exists in the data, apart from the contribution of their long-tailed nature. In addition, an individual’s predictability is correlated with the position of the individual in the static social network derived from the data. Individuals confined in a community—in the sense of an abundance of surrounding triangles—tend to have low predictability, and those bridging different communities tend to have high predictability.

  1. Power conversion technologies

    SciTech Connect

    Haigh, R E

    1998-01-01

    The Power Conservation Technologies thrust area supports initiatives that enhance the core competencies of the Lawrence Livermore National Laboratory (LLNL) Engineering Directorate in the area of solid-state power electronics. Through partnerships with LLNL programs, projects focus on the development of enabling technologies for existing and emerging programs that have unique power conversion requirements. This year, a multi-disciplinary effort was supported which demonstrated solid-state, high voltage generation by using a dense, monolithic photovoltaic array. This effort builds upon Engineering's strengths in the core technology areas of power conversion, photonics, and microtechnologies.

  2. Magnetohydrodynamics and Energy Conversion.

    DTIC Science & Technology

    CIRCUITS, CLOSTRIDIUM TETANI , COILS, ENERGY, FREQUENCY, HEAT TRANSFER, HYDROGEN, INDUCTANCE, LOW PRESSURE, MAGNETIC FIELDS, PINCH EFFECT, PHOTOMULTIPLIER TUBES, RODS, TEMPERATURE, THERMAL CONDUCTIVITY, THERMIONIC EMISSION.

  3. Teaching Conversation with Trivia.

    ERIC Educational Resources Information Center

    Crawford, Michael J.

    2002-01-01

    Presents a rationale for utilizing trivia to teach conversation. Shows how trivia-based materials fit into communicative language teaching approaches and provides examples of trivia-based activities and explains how to use them in the classroom. (Author/VWL)

  4. Clinical Linguistics: Conversational Reflections

    ERIC Educational Resources Information Center

    Crystal, David

    2013-01-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference…

  5. Conversations and Collaborations

    ERIC Educational Resources Information Center

    Korpan, Cynthia

    2010-01-01

    This paper looks at how a series of conversations contributed to the development of a newly formed role at the University of Victoria--Teaching Assistant Consultants (TACs). TACs act as departmental mentors for teaching assistants (TAs) in their respective departments, charged with providing support in the form of discipline-specific workshops…

  6. Mechanochemical Energy Conversion

    ERIC Educational Resources Information Center

    Pines, E.; And Others

    1973-01-01

    Summarizes the thermodynamics of macromolecular systems, including theories and experiments of cyclic energy conversion with rubber and collagen as working substances. Indicates that an early introduction into the concept of chemical potential and solution thermodynamics is made possible through the study of the cyclic processes. (CC)

  7. Ocean thermal energy conversion

    SciTech Connect

    Avery, W.H.

    1983-03-17

    A brief explanation of the Ocean Thermal Energy Conversion (OTEC) concept and an estimate of the amount of energy that can be produced from the ocean resource without introducing environmental concerns are presented. Use of the OTEC system to generate electric power and products which can replace fossil fuels is shown. The OTEC program status and its prospects for the future are discussed.

  8. Electromechanical Energy Conversion.

    ERIC Educational Resources Information Center

    LePage, Wilbur R.

    This programed text on electromechanical energy conversion (motors and generators) was developed under contract with the U.S. Office of Education as Number 12 in a series of materials for use in an electrical engineering sequence. It is intended to be used in conjunction with other materials and with other short texts in the series. (DH)

  9. Conversion or New Building?

    ERIC Educational Resources Information Center

    Berkeley, Phil

    1970-01-01

    Examined first is "the overall problem of housing a TV studio complex to see what particular sorts of buildings are required and how they must be related," and then considered are "the relative merits and particular problems of new studio building or a conversion." (LS)

  10. Planetary image conversion task

    NASA Technical Reports Server (NTRS)

    Martin, M. D.; Stanley, C. L.; Laughlin, G.

    1985-01-01

    The Planetary Image Conversion Task group processed 12,500 magnetic tapes containing raw imaging data from JPL planetary missions and produced an image data base in consistent format on 1200 fully packed 6250-bpi tapes. The output tapes will remain at JPL. A copy of the entire tape set was delivered to US Geological Survey, Flagstaff, Ariz. A secondary task converted computer datalogs, which had been stored in project specific MARK IV File Management System data types and structures, to flat-file, text format that is processable on any modern computer system. The conversion processing took place at JPL's Image Processing Laboratory on an IBM 370-158 with existing software modified slightly to meet the needs of the conversion task. More than 99% of the original digital image data was successfully recovered by the conversion task. However, processing data tapes recorded before 1975 was destructive. This discovery is of critical importance to facilities responsible for maintaining digital archives since normal periodic random sampling techniques would be unlikely to detect this phenomenon, and entire data sets could be wiped out in the act of generating seemingly positive sampling results. Reccomended follow-on activities are also included.

  11. Evaluating Energy Conversion Efficiency

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

    1983-01-01

    Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

  12. A Conversation about Observation

    NASA Technical Reports Server (NTRS)

    Mather, John C.; Mao, Minnie Yuan

    2012-01-01

    In the spirit of the Lindau Meeting, we present a dialogue between a Nobel laureate and a young researcher. This interchange started online, where it continues to unfold. Here is a digest of this conversation, which has developed across time and space.

  13. Leadership is a conversation.

    PubMed

    Groysberg, Boris; Slind, Michael

    2012-06-01

    Globalization and new technologies have sharply reduced the efficacy of command-and-control management and its accompanying forms of corporate communication. In the course of a recent research project, the authors concluded that by talking with employees, rather than simply issuing orders, leaders can promote operational flexibility, employee engagement, and tight strategic alignment. Groysberg and Slind have identified four elements of organizational conversation that reflect the essential attributes of interpersonal conversation: intimacy, interactivity, inclusion, and intentionality. Intimacy shifts the focus from a top-down distribution of information to a bottom-up exchange of ideas. Organizational conversation is less corporate in tone and more casual. And it's less about issuing and taking orders than about asking and answering questions. Interactivity entails shunning the simplicity of monologue and embracing the unpredictable vitality of dialogue. Traditional one-way media-print and broadcast, in particular-give way to social media buttressed by social thinking. Inclusion turns employees into full-fledged conversation partners, entitling them to provide their own ideas, often on company channels. They can create content and act as brand ambassadors, thought leaders, and storytellers. Intentionality enables leaders and employees to derive strategically relevant action from the push and pull of discussion and debate.

  14. Frequency Combs

    NASA Astrophysics Data System (ADS)

    Hänsch, Theodor W.; Picqué, Nathalie

    Much of modern research in the field of atomic, molecular, and optical science relies on lasers, which were invented some 50 years ago and perfected in five decades of intense research and development. Today, lasers and photonic technologies impact most fields of science and they have become indispensible in our daily lives. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. Through the development of optical frequency comb techniques, technique a setup of the size 1 ×1 m2, good for precision measurements of any frequency, and even commercially available, has replaced the elaborate previous frequency-chain schemes for optical frequency measurements, which only worked for selected frequencies. A true revolution in optical frequency measurements has occurred, paving the way for the creation of all-optical clocks clock with a precision that might approach 10-18. A decade later, frequency combs are now common equipment in all frequency metrology-oriented laboratories. They are also becoming enabling tools for an increasing number of applications, from the calibration of astronomical spectrographs to molecular spectroscopy. This chapter first describes the principle of an optical frequency comb synthesizer. Some of the key technologies to generate such a frequency comb are then presented. Finally, a non-exhaustive overview of the growing applications is given.

  15. Solar energy conversion.

    SciTech Connect

    Crabtree, G. W.; Lewis, N. S.

    2008-03-01

    If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience. The Sun has the enormous untapped potential to supply our growing energy needs. The barrier to greater use of the solar resource is its high cost relative to the cost of fossil fuels, although the disparity will decrease with the rising prices of fossil fuels and the rising costs of mitigating their impact on the environment and climate. The cost of solar energy is directly related to the low conversion efficiency, the modest energy density of solar radiation, and the costly materials currently required. The development of materials and methods to improve solar energy conversion is primarily a scientific challenge: Breakthroughs in fundamental understanding ought to enable marked progress. There is plenty of room for improvement, since photovoltaic conversion efficiencies for inexpensive organic and dye-sensitized solar cells are currently about 10% or less, the conversion efficiency of photosynthesis is less than 1%, and the best solar thermal efficiency is 30%. The theoretical limits suggest that we can do much better. Solar conversion is a young science. Its major growth began in the 1970s, spurred by the oil crisis that highlighted the pervasive importance of energy to our personal, social, economic, and political lives. In contrast, fossil-fuel science has developed over more than 250 years, stimulated by the Industrial Revolution and the promise of abundant fossil fuels. The science of thermodynamics, for example, is intimately intertwined with the development of the steam engine. The Carnot cycle, the mechanical equivalent of heat, and entropy all played starring roles in the development of thermodynamics and the technology of heat engines. Solar-energy science faces

  16. Space/Frequency Conversions in Image Processing and Transmission.

    DTIC Science & Technology

    1981-11-01

    oil the’ re Iat ivi’ phase of the il u tminit ing Sglit spit va r iat ioins. driven it by sitausid at frequeiy Jilt. It) tlt.i ha-li Iocsal ilajnt of...ACOoSICI o(Wio s..~viCES APPLIED) TO IMAGE PROCESSING ko crvri Ice I1. Se ve ra I papers ill thiS pr ..... dings srsvisls ty~-is-dais infornial oki oil ...I1ttld. A A Fin. 4. F xamplIe,: r Ix~ rilatteI lllt I tV samjple atray and SCIIrt, I)f (I s nc I a ted I-Dfl tCdt wiltll dIvI lotm I lt 1i)l1exed sI

  17. Frequency Conversion of Single Photons: Physics, Devices, and Applications

    DTIC Science & Technology

    2012-07-01

    that are involved in CHAPTER 4. NOISE PROCESSES IN QFC DEVICES 45 Signal Laser 633 nm Pump Laser 1064 nm PBS RPE PPLN Waveguide L1 L2 Power Meter DM...signal we used a HeNe laser at 632.8 nm in which the power was adjusted using a variable attenuator. The pump laser was a Nd:YAG nonplanar ring oscillator...and spontaneous emission must be filtered. Previous work on upconversion using Tm laser systems used fiber -optic WDMs as filters [32]. Here, we use a

  18. Nonlinear Frequency Conversion in III-V Semiconductor Photonic Crystals

    DTIC Science & Technology

    2012-03-01

    polarizing beamsplitter, SPF : short pass filter, PD: photodiode. The incident light traces the red line into the cavity sample. The second harmonic...33 CCD HWP HWP NPBSOLSample Polarizer Laser PBS PD Monochromator SPF 720 730 740 750 760 770 0 10 20 30 40 50 Wavelength [nm] C o u n ts a. b. c...OL: objective lens, PBS: polarizing beamsplitter, SPF : short pass filter, PD: photodiode. The incident light traces the red line into the cavity

  19. Wind energy conversion system

    DOEpatents

    Longrigg, Paul

    1987-01-01

    The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

  20. Persuasion Detection in Conversation

    DTIC Science & Technology

    2010-03-01

    is the first step in developing machine learning systems that can automatically detect persuasion in conversations. This corpus was developed from...requires some form of persuasion. Based on this research, it may be possible to construct a machine learning system that can automatically detect...specific markers, can these markers be learned and identified by annotators? Our research attempted to answer all of these questions by annotating a

  1. Advanced Thermal Conversion Systems

    DTIC Science & Technology

    2015-03-18

    BAA09-31 3  Figure 1. (a) Energy diagram of the PETE process. Photo -excitation leads to enhanced...photovoltaic cells at 3000x concentration (~38%). As shown in Fig. 2(b), the highest conversion efficiencies are obtained by using photo -cathodes...p-type 4H-SiC (left) and polycrystalline n-type 3C-SiC (right). The fabrication process for p-type devices used bulk p- doped 4H-SiC wafers from

  2. Session: Energy Conversion

    SciTech Connect

    Robertson, David; LaSala, Raymond J.; Kukacka, Lawrence E.; Bliem, Carl J.; Premuzic, Eugene T.; Weare, John H.

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hydrothermal Energy Conversion Technology'' by David Robertson and Raymond J. LaSala; ''Materials for Geothermal Production'' by Lawrence E. Kukacka; ''Supersaturated Turbine Expansions for Binary Geothermal Power Plants'' by Carl J. Bliem; ''Geothermal Waster Treatment Biotechnology: Progress and Advantages to the Utilities'' by Eugen T. Premuzic; and ''Geothermal Brine Chemistry Modeling Program'' by John H. Weare.

  3. Clinical linguistics: conversational reflections.

    PubMed

    Crystal, David

    2013-04-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference participants during that time.

  4. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

    1988-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

  5. Natural gas conversion process

    SciTech Connect

    Not Available

    1992-01-01

    The experimental apparatus was dismantled and transferred to a laboratory space provided by Lawrence Berkeley Laboratory (LBL) which is already equipped with a high-ventilation fume hood. This will enable us to make tests at higher gas flow rates in a safe environment. Three papers presented at the ACS meeting in San Francisco (Symposium on Natural Gas Upgrading II) April 5--10, 1992 show that the goal of direct catalytic conversion of Methane into heavier Hydrocarbons in a reducing atmosphere is actively pursued in three other different laboratories. There are similarities in their general concept with our own approach, but the temperature range of the experiments reported in these recent papers is much lower and this leads to uneconomic conversion rates. This illustrates the advantages of Methane activation by a Hydrogen plasma to reach commercial conversion rates. A preliminary process flow diagram was established for the Integrated Process, which was outlined in the previous Quarterly Report. The flow diagram also includes all the required auxiliary facilities for product separation and recycle of the unconverted feed as well as for the preparation and compression of the Syngas by-product.

  6. Broadband frequency tripling in locally ordered nonlinear photonic crystal.

    PubMed

    Sheng, Yan; Krolikowski, Wieslaw

    2013-02-25

    We propose and fabricate a LiNbO₃-based nonlinear photonic crystal with locally ordered ferroelectric domains. The nonlinearity modulation provides sets of uniformly distributed reciprocal lattice vectors, ensuring broadband high frequency conversion efficiency. Frequency tripling via cascading is demonstrated in the range of 1400-1830 nm, with energy conversion efficiency up to ∼15%.

  7. Microturbine Power Conversion Technology Review

    SciTech Connect

    Staunton, R.H.

    2003-07-21

    In this study, the Oak Ridge National Laboratory (ORNL) is performing a technology review to assess the market for commercially available power electronic converters that can be used to connect microturbines to either the electric grid or local loads. The intent of the review is to facilitate an assessment of the present status of marketed power conversion technology to determine how versatile the designs are for potentially providing different services to the grid based on changes in market direction, new industry standards, and the critical needs of the local service provider. The project includes data gathering efforts and documentation of the state-of-the-art design approaches that are being used by microturbine manufacturers in their power conversion electronics development and refinement. This project task entails a review of power converters used in microturbines sized between 20 kW and 1 MW. The power converters permit microturbine generators, with their non-synchronous, high frequency output, to interface with the grid or local loads. The power converters produce 50- to 60-Hz power that can be used for local loads or, using interface electronics, synchronized for connection to the local feeder and/or microgrid. The power electronics enable operation in a stand-alone mode as a voltage source or in grid-connect mode as a current source. Some microturbines are designed to automatically switch between the two modes. The information obtained in this data gathering effort will provide a basis for determining how close the microturbine industry is to providing services such as voltage regulation, combined control of both voltage and current, fast/seamless mode transfers, enhanced reliability, reduced cost converters, reactive power supply, power quality, and other ancillary services. Some power quality improvements will require the addition of storage devices; therefore, the task should also determine what must be done to enable the power conversion circuits to

  8. Enhanced converse magnetoelectric effect in cylindrical piezoelectric-magnetostrictive composites

    NASA Astrophysics Data System (ADS)

    Wu, Gaojian; Zhang, Ru; Zhang, Ning

    2016-10-01

    Enhanced converse magnetoelectric (ME) effect has been experimentally observed in cylindrical PZT-Terfenol-D piezoelectric-magnetostrictive bilayered composites, where the piezoelectric and magnetostrictive components are coupled through normal stresses instead of shear stresses that act in most of previous multiferroic composites. A theoretical model based on elastodynamics analysis has been proposed to describe the frequency response of converse ME effect for axial and radial modes in the bilayered cylindrical composites. The theory shows good agreement with the experimental results. The different variation tendency of resonant converse ME coefficient, as well as different variation rate of resonance frequency with bias magnetic field for axial and radial modes is interpreted in terms of demagnetizing effect. This work is of theoretical and technological significance for the application of converse ME effect as magnetic sensor, transducers, coil-free flux switch, etc.

  9. [Frequency dependance of compliance].

    PubMed

    Gayrard, P

    1975-01-01

    Resistance of peripheral or "small" airways is only a small part of the total pulmonary resistance (Raw). Even considerable obstruction in these airways will have little effect on total resistance. Conversely this will lead to inequality in the time constants of units in parallel, and dynamic lung compliance (C dyn) shall fall as respiratory frequence increases. C dyn is measured from simultaneous recordings of transpulmonary pressure (esophageal balloon) and volume obtained from a volume displacement plethysmograph. If Raw and static compliance are found to be normal, the frequency dependance of compliance will result from peripheral airway obstruction only. Early stages of chronic airway obstruction can be established by this method. However this appear not suitable for wide-scale studies.

  10. High-efficiency microwave photonic harmonic down-conversion with tunable and reconfigurable filtering.

    PubMed

    Liao, Jinxin; Zheng, Xiaoping; Li, Shangyuan; Zhang, Hanyi; Zhou, Bingkun

    2014-12-01

    A new optical-frequency comb-based microwave photonic harmonic down-convertor with tunable and reconfigurable filtering is proposed and experimentally demonstrated. The coherent evenly spaced optical carriers offer harmonic down-conversion for ultrahigh radio frequency signals with low-frequency local oscillator, and construct a tunable and reconfigurable bandpass filter for the intermediate-frequency (IF) signal combined with dispersion. This implementation features high conversion efficiency. Experimental results show the filtered output IF signal has a clean spectrum with high quality. Measured conversion loss is 8.3 dB without extra electrical amplification.

  11. Microbial Energy Conversion

    SciTech Connect

    Buckley, Merry; Wall, Judy D.

    2006-10-01

    The American Academy of Microbiology convened a colloquium March 10-12, 2006, in San Francisco, California, to discuss the production of energy fuels by microbial conversions. The status of research into various microbial energy technologies, the advantages and disadvantages of each of these approaches, research needs in the field, and education and training issues were examined, with the goal of identifying routes for producing biofuels that would both decrease the need for fossil fuels and reduce greenhouse gas emissions. Currently, the choices for providing energy are limited. Policy makers and the research community must begin to pursue a broader array of potential energy technologies. A diverse energy portfolio that includes an assortment of microbial energy choices will allow communities and consumers to select the best energy solution for their own particular needs. Funding agencies and governments alike need to prepare for future energy needs by investing both in the microbial energy technologies that work today and in the untested technologies that will serve the world’s needs tomorrow. More mature bioprocesses, such as ethanol production from starchy materials and methane from waste digestors, will find applications in the short term. However, innovative techniques for liquid fuel or biohydrogen production are among the longer term possibilities that should also be vigorously explored, starting now. Microorganisms can help meet human energy needs in any of a number of ways. In their most obvious role in energy conversion, microorganisms can generate fuels, including ethanol, hydrogen, methane, lipids, and butanol, which can be burned to produce energy. Alternatively, bacteria can be put to use in microbial fuel cells, where they carry out the direct conversion of biomass into electricity. Microorganisms may also be used some day to make oil and natural gas technologies more efficient by sequestering carbon or by assisting in the recovery of oil and

  12. Crucial Conversations about America's Schools

    ERIC Educational Resources Information Center

    Draper, John C.; Protheroe, Nancy

    2010-01-01

    It's up to school leaders to shift the momentum away from conversations based on misperceptions and toward those that study critical issues about school improvement. "Crucial Conversations About America's Schools" talks about how to do this and provides examples of how to reframe conversations on the hot-button but important topics of…

  13. Special Features in Children's Conversations.

    ERIC Educational Resources Information Center

    Karjalainen, Merja

    In a study of features that seem to be typical of children's conversations, 10 Finnish preschool children's conversations were videotaped and audiotaped over a period of 10 hours. The children were taped in conversation, play, fairy tale, and eating situations. Among the findings are that all children enjoy playing with language, but some initiate…

  14. Conversion to eslicarbazepine acetate monotherapy

    PubMed Central

    French, Jacqueline; Jacobson, Mercedes P.; Pazdera, Ladislav; Gough, Mallory; Cheng, Hailong; Grinnell, Todd; Blum, David

    2016-01-01

    Objective: To assess the efficacy and safety of eslicarbazepine acetate (ESL) monotherapy. Methods: This post hoc pooled analysis of 2 randomized double-blind studies (093-045 and -046) included adults with partial-onset seizures medically uncontrolled by 1 or 2 antiepileptic drugs (AEDs). Following the baseline period (8 weeks), eligible patients were randomized 2:1 to receive ESL 1,600 mg or 1,200 mg once daily for 18 weeks; the primary endpoint was study exit by meeting predefined exit criteria (signifying worsening seizure control). In each study, treatment was considered effective if the upper 95% confidence limit for exit rate was lower than the historical control threshold (65.3%). Results: Pooled exit rates were as follows: ESL 1,600 mg = 20.6% (95% confidence interval: 15.6%–26.8%); ESL 1,200 mg = 30.8% (23.0%–40.5%). Use of 2 baseline AEDs or rescue medication, US location, epilepsy duration ≥20 years, and higher maximum baseline seizure frequency were associated with higher exit risks. Median percent reductions in standardized seizure frequency between baseline and the 18-week double-blind period were as follows: ESL 1,600 mg = 43.2%; ESL 1,200 mg = 35.7%; baseline carbamazepine use was associated with smaller reductions. Safety profiles were similar between ESL doses. Conclusions: Exit rates for ESL monotherapy (1,600 mg and 1,200 mg once daily) were lower than the historical control threshold, irrespective of baseline AED use and region, with no additional safety concerns identified. Clinical factors and location clearly influence treatment responses in conversion-to-monotherapy trials. Classification of evidence: This pooled analysis provides Class IV evidence that for adults with medically uncontrolled partial-onset seizures, ESL monotherapy is well tolerated and effective. PMID:26911639

  15. Zinc phosphate conversion coatings

    DOEpatents

    Sugama, T.

    1997-02-18

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate {alpha}-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal. 33 figs.

  16. Zinc phosphate conversion coatings

    DOEpatents

    Sugama, Toshifumi

    1997-01-01

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

  17. Quantum frequency bridge: high-accuracy characterization of a nearly-noiseless parametric frequency converter.

    PubMed

    Burenkov, Ivan A; Gerrits, Thomas; Lita, Adriana; Nam, Sae Woo; Krister Shalm, L; Polyakov, Sergey V

    2017-01-23

    We demonstrate an efficient and inherently ultra-low noise frequency conversion via a parametric sum frequency generation. Due to the wide separation between the input and pump frequencies and the low pump frequency relative to the input photons, the upconversion results in only ≈100 background photons per hour. To measure such a low rate, we introduced a dark count reduction algorithm for an optical transition edge sensor.

  18. Cell phone conversing while driving in New Zealand: prevalence, risk perception and legislation.

    PubMed

    Hallett, Charlene; Lambert, Anthony; Regan, Michael A

    2011-05-01

    This study investigated (i) the prevalence of conversing on a cell phone while driving in New Zealand, (ii) respondents' perception of risk regarding this behaviour and (iii) attitudes towards legislation banning cell phone use while driving. In addition, the study examined the association between the prevalence of conversing on a cell phone and risk perception. Anonymous, self-reported, survey data was collected via the internet from 1057 drivers nationwide regarding the frequency of conversing on a cell phone, including hands-free and hand-held conversing, risk perception, views on legislation, and demographic information. A positive relationship was found between the frequency of conversing on a cell phone and risk perception; that is, as the frequency of conversing on a cell phone increased, the perceived risk of this behaviour decreased.

  19. Spatial language and converseness.

    PubMed

    Burigo, Michele; Coventry, Kenny R; Cangelosi, Angelo; Lynott, Dermot

    2016-12-01

    Typical spatial language sentences consist of describing the location of an object (the located object) in relation to another object (the reference object) as in "The book is above the vase". While it has been suggested that the properties of the located object (the book) are not translated into language because they are irrelevant when exchanging location information, it has been shown that the orientation of the located object affects the production and comprehension of spatial descriptions. In line with the claim that spatial language apprehension involves inferences about relations that hold between objects it has been suggested that during spatial language apprehension people use the orientation of the located object to evaluate whether the logical property of converseness (e.g., if "the book is above the vase" is true, then also "the vase is below the book" must be true) holds across the objects' spatial relation. In three experiments using sentence acceptability rating tasks we tested this hypothesis and demonstrated that when converseness is violated people's acceptability ratings of a scene's description are reduced indicating that people do take into account geometric properties of the located object and use it to infer logical spatial relations.

  20. Natural gas conversion process

    SciTech Connect

    Not Available

    1991-01-01

    The main objective is to design and operate a laboratory apparatus for the catalytic reforming of natural gas in order to provide data for a large-scale process. To accelerate the assembly and calibration of this equipment, a request has been made to the Lawrence Berkeley Laboratory for assistance, under the DOE's Industrial Visitor Exchange Program. Pr. Heinz Heinemann (Catalysis), Dr. John Apps (Geochemistry) and Dr. Robert Fulton (Mechanical Engineering) have expressed interest in supporting our request. Pr. Heinemann's recent results on the conversion of Petroleum Coke residues into CO2 and H2 mixtures using highly basic metal oxides catalysts, similar to ours, are very encouraging regarding the possibility of converting the Coke residue on our catalyst into Syngas in the Regenerator/riser, as proposed. To minimize Coke formation in the vapor phase, by the Plasmapyrolytic Methane Conversion reactions, the experimental data of H. Drost et al. (Ref. 12) have been reviewed. Work is underway to design equipment for the safe and non-polluting disposal of the two gaseous product streams of the flow loop. 2 refs.

  1. Energy conversion system

    DOEpatents

    Murphy, L.M.

    1985-09-16

    The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.

  2. Energy conversion system

    DOEpatents

    Murphy, Lawrence M.

    1987-01-01

    The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.

  3. Direct somatic lineage conversion

    PubMed Central

    Tanabe, Koji; Haag, Daniel; Wernig, Marius

    2015-01-01

    The predominant view of embryonic development and cell differentiation has been that rigid and even irreversible epigenetic marks are laid down along the path of cell specialization ensuring the proper silencing of unrelated lineage programmes. This model made the prediction that specialized cell types are stable and cannot be redirected into other lineages. Accordingly, early attempts to change the identity of somatic cells had little success and was limited to conversions between closely related cell types. Nuclear transplantation experiments demonstrated, however, that specialized cells even from adult mammals can be reprogrammed into a totipotent state. The discovery that a small combination of transcription factors can reprogramme cells to pluripotency without the need of oocytes further supported the view that these epigenetic barriers can be overcome much easier than assumed, but the extent of this flexibility was still unclear. When we showed that a differentiated mesodermal cell can be directly converted to a differentiated ectodermal cell without a pluripotent intermediate, it was suggested that in principle any cell type could be converted into any other cell type. Indeed, the work of several groups in recent years has provided many more examples of direct somatic lineage conversions. Today, the question is not anymore whether a specific cell type can be generated by direct reprogramming but how it can be induced. PMID:26416679

  4. Conversion program in Sweden

    SciTech Connect

    Jonsson, E.B.

    1997-08-01

    The conversion of the Swedish 50 MW R2 reactor from HEU to LEU fuel has been successfully accomplished over a 16 cycles long process. The conversion started in January 1991 with the introduction of 6 LEU assemblies in the 8*8 core. The first all LEU core was loaded in March 1993 and physics measurements were performed for the final licensing reports. A total of 142 LEU fuel assemblies have been irradiated up until September 1994 without any fuel incident. The operating licence for the R2 reactor was renewed in mid 1994 taking into account new fuel type. The Swedish Nuclear Inspectorate (SKI) pointed out one crucial problem with the LEU operation, that the back end of the LEU fuel cycle has not yet been solved. For the HEU fuel Sweden had the reprocessing alternative. The country is now relying heavily on the success of the USDOEs Off Site Fuels Policy to take back the spent fuel from the research reactors. They have in the meantime increased their intermediate storage facilities. There is, however, a limit both in time and space for storage of MTR-type of assemblies in water. The penalty of the lower thermal neutron flux in LEU cores has been reduced by improvements of the new irradiation rigs and by fine tuning the core calculations. The Studsvik code package, CASMO-SIMULATE, widely used for ICFM in LWRs has been modified to suit the compact MTR type of core.

  5. Light alkane conversion

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1991-07-09

    This patent describes a process for the aromatization of an aliphatic feedstream. It comprises fluidizing finely divided solid particles in a combustion zone; charging oxygen-containing combustion gas and fuel to the combustion zone under combustion conditions; withdrawing a stream of finely divided particles from the combustion zone; flowing the withdrawn stream of finely divided particles above to a cracking/dehydrogenation zone; fluidizing the finely divided particles above in an aliphatic feedstream under conditions within the cracking/dehydrogenation zone controlled to at least partially crack and at least partially dehydrogenate the aliphatic feedstream to form an intermediate product stream containing a quantity of C{sub 4}-olefins such that the exothermic catalytic conversion of the C{sub 4}-olefins is sufficient to supply a portion of the endothermic heat of reaction for the endothermic catalytic conversion of paraffins contained in the intermediate feedstream to aromatics; contacting the intermediate product stream with an aromatization catalyst under aromatization conditions sufficient to evolve an aromatics-rich products stream.

  6. Power conversion technologies

    SciTech Connect

    Newton, M. A.

    1997-02-01

    The Power Conversion Technologies thrust area identifies and sponsors development activities that enhance the capabilities of engineering at Lawrence Livermore National Laboratory (LLNL) in the area of solid- state power electronics. Our primary objective is to be a resource to existing and emerging LLNL programs that require advanced solid-state power electronic technologies.. Our focus is on developing and integrating technologies that will significantly impact the capability, size, cost, and reliability of future power electronic systems. During FY-96, we concentrated our research efforts on the areas of (1) Micropower Impulse Radar (MIR); (2) novel solid-state opening switches; (3) advanced modulator technology for accelerators; (4) compact accelerators; and (5) compact pulse generators.

  7. Thermal Energy Conversion Branch

    NASA Technical Reports Server (NTRS)

    Bielozer, Matthew C.; Schreiber, Jeffrey, G.; Wilson, Scott D.

    2004-01-01

    The Thermal Energy Conversion Branch (5490) leads the way in designing, conducting, and implementing research for the newest thermal systems used in space applications at the NASA Glenn Research Center. Specifically some of the most advanced technologies developed in this branch can be broken down into four main areas: Dynamic Power Systems, Primary Solar Concentrators, Secondary Solar Concentrators, and Thermal Management. Work was performed in the Dynamic Power Systems area, specifically the Stirling Engine subdivision. Today, the main focus of the 5490 branch is free-piston Stirling cycle converters, Brayton cycle nuclear reactors, and heat rejection systems for long duration mission spacecraft. All space exploring devices need electricity to operate. In most space applications, heat energy from radioisotopes is converted to electrical power. The Radioisotope Thermoelectric Generator (RTG) already supplies electricity for missions such as the Cassini Spacecraft. The focus of today's Stirling research at GRC is aimed at creating an engine that can replace the RTG. The primary appeal of the Stirling engine is its high system efficiency. Because it is so efficient, the Stirling engine will significantly reduce the plutonium fuel mission requirements compared to the RTG. Stirling is also being considered for missions such as the lunar/Mars bases and rovers. This project has focused largely on Stirling Engines of all types, particularly the fluidyne liquid piston engine. The fluidyne was developed by Colin D. West. This engine uses the same concepts found in any type of Stirling engine, with the exception of missing mechanical components. All the working components are fluid. One goal was to develop and demonstrate a working Stirling Fluidyne Engine at the 2nd Annual International Energy Conversion Engineering Conference in Providence, Rhode Island.

  8. The Role of Conversation Policy in Carrying Out Agent Conversations

    SciTech Connect

    Link, Hamilton E.; Phillips, Laurence R.

    1999-05-20

    Structured conversation diagrams, or conversation specifications, allow agents to have predictable interactions and achieve predefined information-based goals, but they lack the flexibility needed to function robustly in an unpredictable environment. We propose a mechanism that combines a typical conversation structure with a separately established policy to generate an actual conversation. The word "policy" connotes a high-level direction external to a specific planned interaction with the environment. Policies, which describe acceptable procedures and influence decisions, can be applied to broad sets of activity. Based on their observation of issues related to a policy, agents may dynamically adjust their communication patterns. The policy object describes limitations, constraints, and requirements that may affect the conversation in certain circumstances. Using this new mechanism of interaction simplifies the description of individual conversations and allows domain-specific issues to be brought to bear more easily during agent communication. By following the behavior of the conversation specification when possible and deferring to the policy to derive behavior in exceptional circumstances, an agent is able to function predictably under normal situations and still act rationally in abnormal situations. Different conversation policies applied to a given conversation specification can change the nature of the interaction without changing the specification.

  9. Large-scale Analysis of Counseling Conversations: An Application of Natural Language Processing to Mental Health

    PubMed Central

    Althoff, Tim; Clark, Kevin; Leskovec, Jure

    2016-01-01

    Mental illness is one of the most pressing public health issues of our time. While counseling and psychotherapy can be effective treatments, our knowledge about how to conduct successful counseling conversations has been limited due to lack of large-scale data with labeled outcomes of the conversations. In this paper, we present a large-scale, quantitative study on the discourse of text-message-based counseling conversations. We develop a set of novel computational discourse analysis methods to measure how various linguistic aspects of conversations are correlated with conversation outcomes. Applying techniques such as sequence-based conversation models, language model comparisons, message clustering, and psycholinguistics-inspired word frequency analyses, we discover actionable conversation strategies that are associated with better conversation outcomes.

  10. New frequency translation technique for FM-CW reflectometrya)

    NASA Astrophysics Data System (ADS)

    Meneses, Luis; Cupido, Luis; Manso, M. E.; Jet-Efda Contributors

    2010-10-01

    In broadband microwave reflectometry, coherent detection is widely used to obtain the phase information and to improve the systems sensitivity, both in diagnostics measuring the electronic density profile and plasma fluctuations. Coherent detection uses a translated version of the probing signal to guarantee a stable intermediate frequency. Here, a novel technique to generate the frequency translation by double frequency conversion is presented and its advantages over the commonly used single frequency conversion techniques employing image rejection mixers are discussed. The results obtained with the new frequency translator modules developed for the three JET FM-CW reflectometers, operating successfully at JET since mid-2009, are presented.

  11. Energy conversion apparatus

    SciTech Connect

    Porter, D.R.

    1988-10-18

    This patent describes an energy conversion apparatus comprising: an engine, the engine comprising a cylinder and a piston reciprocally mounted therein, the cylinder defining a combustion chamber on one side of the piston for receiving a fuel mixture and a fluid drive chamber on the other side of the piston for receiving hydraulic fluid, a turbine, the turbine comprising a housing and a vaned turbine wheel rotatably mounted on a drive shaft journalled in the housing, hydraulic means for coupling fluid in the fluid drive chamber of the cylinder with the housing for rotatably driving the turbine wheel and the drive shaft upon a given movement of the piston, means for providing the combustion chamber of the engine with a fuel mixture comprising hydrogen and oxygen, an ignition means for selectively igniting the mixture in the combustion chamber, and purging means for selectively rotating the turbine prior to ignition of the fuel mixture in the engine to remove air therefrom, the purging means comprising a pump means for moving fluid from the reservoir into the fluid drive chambers, the conduit means and the turbine housing, whereby the piston driven by the ignited fuel mixture forces fluid in the fluid drive chamber against the vanes of the turbine wheel to rotate the drive shaft.

  12. Geothermal energy conversion facility

    SciTech Connect

    Kutscher, C.F.

    1997-12-31

    With the termination of favorable electricity generation pricing policies, the geothermal industry is exploring ways to improve the efficiency of existing plants and make them more cost-competitive with natural gas. The Geothermal Energy Conversion Facility (GECF) at NREL will allow researchers to study various means for increasing the thermodynamic efficiency of binary cycle geothermal plants. This work has received considerable support from the US geothermal industry and will be done in collaboration with industry members and utilities. The GECF is being constructed on NREL property at the top of South Table Mountain in Golden, Colorado. As shown in Figure 1, it consists of an electrically heated hot water loop that provides heating to a heater/vaporizer in which the working fluid vaporizes at supercritical or subcritical pressures as high as 700 psia. Both an air-cooled and water-cooled condenser will be available for condensing the working fluid. In order to minimize construction costs, available equipment from the similar INEL Heat Cycle Research Facility is being utilized.

  13. Microbial conversion of coal

    SciTech Connect

    Bean, R.M. )

    1989-10-01

    The objectives of this project were to describe in detail the degradation of coals by fungi and microbes, to expand the range of applicability of the process to include new microbes and other coal types, to identify the means by which biosolubilization of coal is accomplished, and to explore means to enhance the rates and extent of coal bioconversion. The project was initiated in a response to the discovery by Dr. Martin Cohen at the University of Hartford, of a fungal strain of Coriolus versicolor that would render a solid coal substance, leonardite, into a liquid product. The project has identified the principal agent of leonardite solubilization as a powerful metal chelator, most likely a fungal-produced siderophore. Another nonlaccase enzyme has also been identified as a unique biosolubilizing agent produced by C. versicolor. Assays were developed for the quantitative determination of biological coal conversion, and for the determination of potency of biosolubilizing agent. Screening studies uncovered several microbial organisms capable of coal biodegradation, and led to the discovery that prolonged heating in air at the moderate temperature of 150{degree}C allowed the biodegradation of Illinois {number sign}6 coal to material soluble in dilute base. Chemical studies showed that leonardite biosolubilization was accompanied by relatively small change in composition, while solubilization of Illinois {number sign}6 coal involves considerable oxidation of the coal. 24 refs., 32 figs., 27 tabs.

  14. Solar energy conversion apparatus

    SciTech Connect

    Nash, S.G.

    1983-10-18

    Solar energy conversion apparatus is disclosed including a housing portion, an energy absorbing portion, a fluid directing portion and a cover portion; the housing portion including a molded plastic pan member including a base section with upwardly extending spaced spacer sections, the pan member including outwardly inclined sidewall sections having spaced inner and outer wall sections with a top section including an outwardly extending flange section and an inwardly extending slotted frame section; the energy absorbing portion including a conductive metal liner member positioned within the housing portion and resting on the upper surfaces of the spacer sections, a conductive metal separator section extending between the liner sidewall sections adjacent the upper ends thereof and enclosing the liner member; the fluid directing portion including a plurality of parallel spaced longitudinal baffle members arranged in a staggered relationship to provide a tortuous fluid path through the apparatus, an inlet opening and an outlet opening to the tortuous path, the baffle members extending upwardly from the liner bottom to the separator section; the cover portion including transparent impact resistant flat and dome members, the edges of the flat member being secured to the top section, the dome member being disposed over the flat member with its edges engaged with the flange section slots, the dome member including flat sections extending upwardly at an angle of 20/sup 0/ to 30/sup 0/ and a convex central section joining the flat sections.

  15. Mode conversion in plasmas with two-dimensional inhomogeneities

    NASA Astrophysics Data System (ADS)

    Nassiri-Mofakham, Nora; Sabzevari, Bijan Sh.

    2006-02-01

    Most of the mode conversion theories considered so far assume only a plane-layered medium, i.e. a medium where the parameters depend on one spatial coordinate. We generalize the mode-conversion method of Cairns and Lashmore-Davies to plasmas with two-dimensional inhomogeneities. In the method presented here, the frequencies ω_1 and ω_2 of the uncoupled modes belonging to two different dispersion equations are considered as functions of the space variable r and the wave vector k and are coupled together via a small quantity η. We calculate the energy transmission and conversion coefficients analytically by solving two coupled wave amplitude equations in the electron cyclotron range of frequencies. The results are applicable to electron Bernstein wave heating of plasmas with two-dimensional inhomogeneity, e.g. spherical tokamaks.

  16. LH wave absorption by mode conversion near ion cyclotron harmonics

    SciTech Connect

    Ko, K.; Bers, A.; Fuchs, V.

    1981-02-01

    Numerical studies of the dispersion relation near the lower-hybrid frequency in an inhomogeneous plasma (..delta.. n, ..delta.. T, ..delta.. B) show that portions of an incident lower-hybrid wave spectrum undergo successive but partial mode conversions to warm-plasma waves in the presence of ion cyclotron harmonics. Wave absorption beyond the first mode conversion occurs near an ion cyclotron harmonic where ion Landau damping is enhanced. A second-order dispersion relation numerically in good agreement with the full dispersion relation in the mode conversion region is derived using the condition par. delta D/par. delta k = 0. The mode conversion efficiency at each confluence is evaluated by solving the corresponding differential equation.

  17. Frequency doubling crystals

    DOEpatents

    Wang, Francis; Velsko, Stephan P.

    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.

  18. Thermoacoustic power conversion using a piezoelectric transducer.

    PubMed

    Jensen, Carl; Raspet, Richard

    2010-07-01

    The predicted efficiency of a simple thermoacoustic waste heat power conversion device has been investigated as part of a collaborative effort combining a thermoacoustic engine with a piezoelectric transducer. Symko et al. [Microelectron. J. 35, 185-191 (2004)] at the University of Utah built high frequency demonstration engines for this application, and Lynn [ASMDC report, accession number ADA491030 (2008)] at the University of Washington designed and built a high efficiency piezoelectric unimorph transducer for electroacoustic conversion. The design presented in this paper is put forward to investigate the potential of a simple high frequency, air filled, standing wave thermoacoustic device to be competitive with other small generator technologies such as thermoelectric devices. The thermoacoustic generator is simulated using a low-amplitude approximation for thermoacoustics and the acoustic impedance of the transducer is modeled using an equivalent circuit model calculated from the transducer's mechanical and electrical properties. The calculations demonstrate that a device performance of around 10% of Carnot efficiency could be expected from the design which is competitive with currently available thermoelectric generators.

  19. Selecting a Retrospective Conversion Vendor.

    ERIC Educational Resources Information Center

    Lisowski, Andrew; Sessions, Judith

    1984-01-01

    Discussion of using vendors for retrospective conversion of library catalogs rather than in-house projects highlights reasons to consider vendors, four conversion methodologies, and vendor selection criteria (database, non-matches, local data, accuracy, charging, schedule, product delivery time, local system compatibility, MARC format, impact on…

  20. In Conversation with Jim Blair

    ERIC Educational Resources Information Center

    Holman, Andrew

    2012-01-01

    Jim Blair is the only consultant nurse working with people with learning disabilities in the country. His job helps make people better and saves money. This article shares a conversation with Jim Blair. In the conversation, Blair says he is unhappy Valuing People programme did not do as much as it could have done. Jim is worried all the changes,…

  1. Language Teacher Educators Collaborative Conversations.

    ERIC Educational Resources Information Center

    Bailey, Francis; Hawkins, Maggie; Irujo, Suzanne; Larsen-Freeman, Diane; Rintell, Ellen; Willett, Jerri

    1998-01-01

    Conveys the power and value of collaborative conversation among a small group of language teacher educators who meet regularly to discuss practice. Excerpts from a discussion are presented to show a sample of real issues the teachers face and illustrate how the conversations allow ongoing feedback about real dilemmas from a supportive community of…

  2. Older Siblings as Conversational Partners.

    ERIC Educational Resources Information Center

    Hoff-Ginsberg, Erika; Krueger, Wendy M.

    1991-01-01

    Discusses a study of conversational dyadic interaction between children aged 1.5 to 3 years; their 4-, 5-, 7-, or 8-year-old siblings; and their mothers. Mothers were more supportive conversational partners and adapted their level of speech more than siblings. (GH)

  3. Record Conversion at Oregon State.

    ERIC Educational Resources Information Center

    Watkins, Deane

    1985-01-01

    Describes the conversion of card catalog records at William Jasper Kerr Library, Oregon State University, to an online system. Discussion covers the use of OCLC and student assistants, procedures and specifications, and problems associated with massive retrospective conversion needs and uncertain budget allocations. Eight sources are recommended.…

  4. Faculty Meetings: Hidden Conversational Dynamics

    ERIC Educational Resources Information Center

    Bowman, Richard F.

    2015-01-01

    In the everydayness of faculty meetings, collegial conversations mirror distinctive dynamics and practices, which either enhance or undercut organizational effectiveness. A cluster of conversational practices affect how colleagues connect, engage, interact, and influence others during faculty meetings in diverse educational settings. The…

  5. Conversational Competence in Academic Settings

    ERIC Educational Resources Information Center

    Bowman, Richard F.

    2014-01-01

    Conversational competence is a process, not a state. Ithaca does not exist, only the voyage to Ithaca. Vibrant campuses are a series of productive conversations. At its core, communicative competence in academic settings mirrors a collective search for meaning regarding the purpose and direction of a campus community. Communicative competence…

  6. Wide-band quantum interface for visible-to-telecommunication wavelength conversion.

    PubMed

    Ikuta, Rikizo; Kusaka, Yoshiaki; Kitano, Tsuyoshi; Kato, Hiroshi; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

    2011-11-15

    Although near-infrared photons in telecommunication bands are required for long-distance quantum communication, various quantum information tasks have been performed by using visible photons for the past two decades. Recently, such visible photons from diverse media including atomic quantum memories have also been studied. Optical frequency down-conversion from visible to telecommunication bands while keeping the quantum states is thus required for bridging such wavelength gaps. Here we report demonstration of a quantum interface of frequency down-conversion from visible to telecommunication bands by using a nonlinear crystal, which has a potential to work over wide bandwidths, leading to a high-speed interface of frequency conversion. We achieved the conversion of a picosecond visible photon at 780  nm to a 1,522-nm photon, and observed that the conversion process retained entanglement between the down-converted photon and another photon.

  7. Methods for locating ground faults and insulation degradation condition in energy conversion systems

    DOEpatents

    Agamy, Mohamed; Elasser, Ahmed; Galbraith, Anthony William; Harfman Todorovic, Maja

    2015-08-11

    Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

  8. Petite fabrique de conversation francaise (Little Factory of French Conversation).

    ERIC Educational Resources Information Center

    Dubroca, Danielle

    1987-01-01

    A technique using dialogues and realistic prose passages from the works of Georges Simenon and Simone de Beauvoir to teach French conversational skills at the college level is explained and illustrated. (MSE)

  9. Roadmap on optical energy conversion

    SciTech Connect

    Boriskina, Svetlana V.; Green, Martin A.; Catchpole, Kylie; Yablonovitch, Eli; Beard, Matthew C.; Okada, Yoshitaka; Lany, Stephan; Gershon, Talia; Zakutayev, Andriy; Tahersima, Mohammad H.; Sorger, Volker J.; Naughton, Michael J.; Kempa, Krzysztof; Dagenais, Mario; Yao, Yuan; Xu, Lu; Sheng, Xing; Bronstein, Noah D.; Rogers, John A.; Alivisatos, A. Paul; Nuzzo, Ralph G.; Gordon, Jeffrey M.; Wu, Di M.; Wisser, Michael D.; Salleo, Alberto; Dionne, Jennifer; Bermel, Peter; Greffet, Jean-Jacques; Celanovic, Ivan; Soljacic, Marin; Manor, Assaf; Rotschild, Carmel; Raman, Aaswath; Zhu, Linxiao; Fan, Shanhui; Chen, Gang

    2016-06-24

    For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light-matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap

  10. Roadmap on optical energy conversion

    NASA Astrophysics Data System (ADS)

    Boriskina, Svetlana V.; Green, Martin A.; Catchpole, Kylie; Yablonovitch, Eli; Beard, Matthew C.; Okada, Yoshitaka; Lany, Stephan; Gershon, Talia; Zakutayev, Andriy; Tahersima, Mohammad H.; Sorger, Volker J.; Naughton, Michael J.; Kempa, Krzysztof; Dagenais, Mario; Yao, Yuan; Xu, Lu; Sheng, Xing; Bronstein, Noah D.; Rogers, John A.; Alivisatos, A. Paul; Nuzzo, Ralph G.; Gordon, Jeffrey M.; Wu, Di M.; Wisser, Michael D.; Salleo, Alberto; Dionne, Jennifer; Bermel, Peter; Greffet, Jean-Jacques; Celanovic, Ivan; Soljacic, Marin; Manor, Assaf; Rotschild, Carmel; Raman, Aaswath; Zhu, Linxiao; Fan, Shanhui; Chen, Gang

    2016-07-01

    For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light-matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap

  11. Energy conversion and storage program

    NASA Astrophysics Data System (ADS)

    1990-12-01

    The Energy Conversion and Storage Program applies chemical and chemical engineering principles to solve problems in (1) production of new synthetic fuels; (2) development of high-performance rechargeable batteries and fuel cells; (3) development of advanced thermochemical processes for energy storage; (4) characterization of complex chemical processes; and (5) the application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, and advanced methods of analysis. The following five areas are discussed: electrochemical energy storage and conversion; microstructured materials; biotechnology; fossil fuels; and high temperature superconducting processing. Papers have been processed separately for inclusion on the data base.

  12. The Sensitive Infrared Signal Detection by Sum Frequency Generation

    NASA Technical Reports Server (NTRS)

    Wong, Teh-Hwa; Yu, Jirong; Bai, Yingxin

    2013-01-01

    An up-conversion device that converts 2.05-micron light to 700 nm signal by sum frequency generation using a periodically poled lithium niobate crystal is demonstrated. The achieved 92% up-conversion efficiency paves the path to detect extremely weak 2.05-micron signal with well established silicon avalanche photodiode detector for sensitive lidar applications.

  13. Dynamic Conversion Working Group Summary

    NASA Technical Reports Server (NTRS)

    Chaffee, N.; Sovie, R. J.

    1984-01-01

    The potential of dynamic conversion devices for use in solar and nuclear dynamic space power systems was addressed. Conversion systems considered were based on the use of Brayton, Stirling and Rankine cycles. Both organic and liquid metal Rankine cycles were included. The basic system considerations were: mission requirements, system attributes, system options, technology issues and constraints, and priorities of needed technology development. Mission requirements, where dynamic conversion was considered enabling technology, were identified along with the associated power levels and potential energy sources. When considering the system options special attention was given to recommend operating temperatures and other significant discriminators. A list of prioritized tasks considered important for the successful development of dynamic conversion systems for 1995 and beyond was compiled.

  14. Conversational topics in transsexual persons.

    PubMed

    Van Borsel, John; Cayzeele, Miet; Heirman, Eva; T'sjoen, Guy

    2014-06-01

    Abstract In general, speech language therapy for transsexual persons focuses on pitch and pitch variation and more recently also on resonance. Other communicative aspects are dealt with far less often, especially language. This study investigated to what extent conversational topics might need attention in therapy for transsexual persons. A total of 111 males, 116 females, 28 male-to-female and 18 female-to-male transsexuals were asked to indicate on a list with 34 topics how often they speak about each topic (never, sometimes, often) in conversations with males, with females and in a gender mixed group. Results showed that transsexual persons behave in accordance with the desired gender. However, they also tend to adopt a position depending on the gender of their conversational partner. It can be concluded that in general it is not necessary to pay attention to conversational topics in therapy for transsexual persons.

  15. Energy conversion at dipolarization fronts

    NASA Astrophysics Data System (ADS)

    Khotyaintsev, Yu. V.; Divin, A.; Vaivads, A.; André, M.; Markidis, S.

    2017-02-01

    We use multispacecraft observations by Cluster in the Earth's magnetotail and 3-D particle-in-cell simulations to investigate conversion of electromagnetic energy at the front of a fast plasma jet. We find that the major energy conversion is happening in the Earth (laboratory) frame, where the electromagnetic energy is being transferred from the electromagnetic field to particles. This process operates in a region with size of the order several ion inertial lengths across the jet front, and the primary contribution to E·j is coming from the motional electric field and the ion current. In the frame of the front we find fluctuating energy conversion with localized loads and generators at sub-ion scales which are primarily related to the lower hybrid drift instability excited at the front; however, these provide relatively small net energy conversion.

  16. Enzymes for improved biomass conversion

    SciTech Connect

    Brunecky, Roman; Himmel, Michael E.

    2016-02-02

    Disclosed herein are enzymes and combinations of the enzymes useful for the hydrolysis of cellulose and the conversion of biomass. Methods of degrading cellulose and biomass using enzymes and cocktails of enzymes are also disclosed.

  17. Virginia Hamilton: Continuing the Conversation.

    ERIC Educational Resources Information Center

    Mikkelsen, Nina

    1995-01-01

    Relates the latest installment of a continuing conversation between the author and Virginia Hamilton. Discusses ethnicity and identity, environmental issues, the creative process, and the way heritage, history, and family storytelling affect a writer's work. (RS)

  18. NASA thermionic-conversion program

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1977-01-01

    Technological processes in out-of-core thermionic energy conversion are described. The emphasis was on high temperature electrode materials and system engineering of converter geometries to produce practical power densities.

  19. Effective communication during difficult conversations.

    PubMed

    Polito, Jacquelyn M

    2013-06-01

    A strong interest and need exist in the workplace today to master the skills of conducting difficult conversations. Theories and strategies abound, yet none seem to have found the magic formula with universal appeal and success. If it is such an uncomfortable skill to master is it better to avoid or initiate such conversations with employees? Best practices and evidence-based management guide us to the decision that quality improvement dictates effective communication, even when difficult. This brief paper will offer some suggestions for strategies to manage difficult conversations with employees. Mastering the skills of conducting difficult conversations is clearly important to keeping lines of communication open and productive. Successful communication skills may actually help to avert confrontation through employee engagement, commitment and appropriate corresponding behavior

  20. A Conversation Well Worth Remembering

    ERIC Educational Resources Information Center

    Woolven-Allen, John

    2009-01-01

    To mark the 200th anniversary of Charles Darwin's birth, a special event was held at Oxford, which included a "Conversation" between Professor Richard Dawkins and Bishop Richard Harries. Here we present a personal reminiscence of the event.

  1. Development of Geodetic Conversion Routines

    DTIC Science & Technology

    2001-09-01

    horizontal and vertical datums in the United States. It provides examples to invoke the Dynamic Link Library and use conversion functions in various programming languages, such as Visual Basic , C, and C++.

  2. Serious Illness Conversations in ESRD.

    PubMed

    Mandel, Ernest I; Bernacki, Rachelle E; Block, Susan D

    2016-12-28

    Dialysis-dependent ESRD is a serious illness with high disease burden, morbidity, and mortality. Mortality in the first year on dialysis for individuals over age 75 years old approaches 40%, and even those with better prognoses face multiple hospitalizations and declining functional status. In the last month of life, patients on dialysis over age 65 years old experience higher rates of hospitalization, intensive care unit admission, procedures, and death in hospital than patients with cancer or heart failure, while using hospice services less. This high intensity of care is often inconsistent with the wishes of patients on dialysis but persists due to failure to explore or discuss patient goals, values, and preferences in the context of their serious illness. Fewer than 10% of patients on dialysis report having had a conversation about goals, values, and preferences with their nephrologist, although nearly 90% report wanting this conversation. Many nephrologists shy away from these conversations, because they do not wish to upset their patients, feel that there is too much uncertainty in their ability to predict prognosis, are insecure in their skills at broaching the topic, or have difficulty incorporating the conversations into their clinical workflow. In multiple studies, timely discussions about serious illness care goals, however, have been associated with enhanced goal-consistent care, improved quality of life, and positive family outcomes without an increase in patient distress or anxiety. In this special feature article, we will (1) identify the barriers to serious illness conversations in the dialysis population, (2) review best practices in and specific approaches to conducting serious illness conversations, and (3) offer solutions to overcome barriers as well as practical advice, including specific language and tools, to implement serious illness conversations in the dialysis population.

  3. 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

  4. On-chip optical mode conversion based on dynamic grating in photonic-phononic hybrid waveguide

    PubMed Central

    Chen, Guodong; Zhang, Ruiwen; Sun, Junqiang

    2015-01-01

    We present a scheme for reversible and tunable on-chip optical mode conversion based on dynamic grating in a hybrid photonic-phononic waveguide. The dynamic grating is built up through the acousto-optic effect and the theoretical model of the optical mode conversion is developed by considering the geometrical deformation and refractive index change. Three kinds of mode conversions are able to be realized using the same hybrid waveguide structure in a large bandwidth by only changing the launched acoustic frequency. The complete mode conversion can be achieved by choosing a proper acoustic power under a given waveguide length. PMID:25996236

  5. 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.

  6. Radio-over-fiber DSB-to-SSB conversion using semiconductor lasers at stable locking dynamics.

    PubMed

    Hsieh, Kun-Lin; Hung, Yu-Han; Hwang, Sheng-Kwang; Lin, Chien-Chung

    2016-05-02

    In radio-over-fiber systems, optical single-sideband (SSB) modulation signals are preferred to optical double-sideband (DSB) modulation signals for fiber distribution in order to mitigate the microwave power fading effect. However, typically adopted modulation schemes generate DSB signals, making DSB-to-SSB conversion necessary before or after fiber distribution. This study investigates a semiconductor laser at stable locking dynamics for such conversion. The conversion relies solely on the nonlinear dynamical interaction between an input DSB signal and the laser. Only a typical semiconductor laser is therefore required as the key conversion unit, and no pump or probe signal is necessary. The conversion can be achieved for a broad tunable range of microwave frequency up to at least 60 GHz. In addition, the conversion can be carried out even when the microwave frequency, the power of the input DSB signal, or the frequency of the input DSB signal fluctuates over a wide range, leading to high adaptability and stability of the conversion system. After conversion, while the microwave phase quality, such as linewidth and phase noise, is mainly preserved, a bit-error ratio down to 10-9 is achieved for a data rate up to at least 8 Gb/s with a detection sensitivity improvement of more than 1.5 dB.

  7. Energy Conversion and Storage Program

    NASA Astrophysics Data System (ADS)

    Cairns, E. J.

    1993-06-01

    This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.

  8. Asymptotic cost in document conversion

    NASA Astrophysics Data System (ADS)

    Blostein, Dorothea; Nagy, George

    2012-01-01

    In spite of a hundredfold decrease in the cost of relevant technologies, the role of document image processing systems is gradually declining due to the transition to an on-line world. Nevertheless, in some high-volume applications, document image processing software still saves millions of dollars by accelerating workflow, and similarly large savings could be realized by more effective automation of the multitude of low-volume personal document conversions. While potential cost savings, based on estimates of costs and values, are a driving force for new developments, quantifying such savings is difficult. The most important trend is that the cost of computing resources for DIA is becoming insignificant compared to the associated labor costs. An econometric treatment of document processing complements traditional performance evaluation, which focuses on assessing the correctness of the results produced by document conversion software. Researchers should look beyond the error rate for advancing both production and personal document conversion.

  9. Conversations with Environmental Educators: A Conversation with Four Classroom Teachers

    ERIC Educational Resources Information Center

    Volk, Trudi L.

    2003-01-01

    This article includes a conversation with four environmental education classroom teachers. The author introduces the four classroom teachers, Marie Marrs, Barb Pietrucha, Vicki Newberry, and Dara Lukonen. In the interview, the four environmental education classroom teachers describe the environmental education in their classrooms. Three of these…

  10. La Conversation par le theatre (Conversation through Theater).

    ERIC Educational Resources Information Center

    Bayoff, Marie-Jose

    1986-01-01

    A successful advanced college-level French conversation course using French theater as a basis for students to learn oral skills has six phases: an overview of the history of French theater, reading, adaptation of the text, rehearsal-readings, final rehearsals, and performance. (MSE)

  11. Power conversion in electrical networks

    NASA Technical Reports Server (NTRS)

    Wood, J. R.

    1974-01-01

    Aspects of dc to dc conversion were studied in terms of a class of switching voltage regulators from a stability viewpoint. Background concepts of nonlinear system theory were considered, including the problem of obtaining suitable realizations for a class of positive operators. It is shown that the state evolution equations for a power conversion network are in general of bilinear form, and that the theory of lie groups and lie algebras is useful in analyzing such systems. The feedback stabilization of a class of bilinear systems whose state space is a manifold is also discussed.

  12. Review of betavoltaic energy conversion

    NASA Technical Reports Server (NTRS)

    Olsen, Larry C.

    1993-01-01

    Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.

  13. Pronunciation models for conversational speech

    NASA Astrophysics Data System (ADS)

    Johnson, Keith

    2005-09-01

    Using a pronunciation dictionary of clear speech citation forms a segment deletion rate of nearly 12% is found in a corpus of conversational speech. The number of apparent segment deletions can be reduced by constructing a pronunciation dictionary that records one or more of the actual pronunciations found in conversational speech; however, the resulting empirical pronunciation dictionary often fails to include the citation pronunciation form. Issues involved in selecting pronunciations for a dictionary for linguistic, psycholinguistic, and ASR research will be discussed. One conclusion is that Ladefoged may have been the wiser for avoiding the business of producing pronunciation dictionaries. [Supported by NIDCD Grant No. R01 DC04330-03.

  14. Recirculation in multiple wave conversions

    SciTech Connect

    Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N.; Tracy, E.R.

    2008-07-30

    A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.

  15. Frequency Doubling Broadband Light in Multiple Crystals

    SciTech Connect

    ALFORD,WILLIAM J.; SMITH,ARLEE V.

    2000-07-26

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

  16. Self-induced neutrino flavor conversion without flavor mixing

    SciTech Connect

    Chakraborty, S.; Izaguirre, I.; Raffelt, G.G.; Hansen, R. S. E-mail: rasmus@mpi-hd.mpg.de E-mail: raffelt@mpp.mpg.de

    2016-03-01

    Neutrino-neutrino refraction in dense media can cause self-induced flavor conversion triggered by collective run-away modes of the interacting flavor oscillators. The growth rates were usually found to be of order a typical vacuum oscillation frequency Δ m{sup 2}/2E. However, even in the simple case of a ν{sub e} beam interacting with an opposite-moving ν-bar {sub e} beam, and allowing for spatial inhomogeneities, the growth rate of the fastest-growing Fourier mode is of order μ=√2 G{sub F} n{sub ν}, a typical ν–ν interaction energy. This growth rate is much larger than the vacuum oscillation frequency and gives rise to flavor conversion on a much shorter time scale. This phenomenon of 'fast flavor conversion' occurs even for vanishing Δ m{sup 2}/2E and thus does not depend on energy, but only on the angle distributions. Moreover, it does not require neutrinos to mix or to have masses, except perhaps for providing seed disturbances. We also construct a simple homogeneous example consisting of intersecting beams and study a schematic supernova model proposed by Ray Sawyer, where ν{sub e} and ν-bar {sub e} emerge with different zenith-angle distributions, the key ingredient for fast flavor conversion. What happens in realistic astrophysical scenarios remains to be understood.

  17. Calculation Methods and Conversions for Pesticide Application.

    ERIC Educational Resources Information Center

    Cole, Herbert, Jr.

    This agriculture extension service publication from Pennsylvania State University consists of conversion tables and formulas for determining concentration and rate of application of pesticides. Contents include: (1) Area and volume conversions; (2) Important conversion formulae; (3) Conversions for rates of application; (4) Quantities of pesticide…

  18. 16 CFR 1012.7 - Telephone conversations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Telephone conversations. 1012.7 Section 1012... AGENCY PERSONNEL AND OUTSIDE PARTIES § 1012.7 Telephone conversations. (a) Telephone conversations... meet with Agency employees. However, because telephone conversations, by their very nature, are...

  19. 16 CFR 1012.7 - Telephone conversations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Telephone conversations. 1012.7 Section 1012... AGENCY PERSONNEL AND OUTSIDE PARTIES § 1012.7 Telephone conversations. (a) Telephone conversations... meet with Agency employees. However, because telephone conversations, by their very nature, are...

  20. 16 CFR 1012.7 - Telephone conversations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Telephone conversations. 1012.7 Section 1012... AGENCY PERSONNEL AND OUTSIDE PARTIES § 1012.7 Telephone conversations. (a) Telephone conversations... meet with Agency employees. However, because telephone conversations, by their very nature, are...

  1. 16 CFR 1012.7 - Telephone conversations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Telephone conversations. 1012.7 Section 1012... AGENCY PERSONNEL AND OUTSIDE PARTIES § 1012.7 Telephone conversations. (a) Telephone conversations... meet with Agency employees. However, because telephone conversations, by their very nature, are...

  2. 16 CFR 1012.7 - Telephone conversations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Telephone conversations. 1012.7 Section 1012... AGENCY PERSONNEL AND OUTSIDE PARTIES § 1012.7 Telephone conversations. (a) Telephone conversations... meet with Agency employees. However, because telephone conversations, by their very nature, are...

  3. Energy Conversion and Storage Program

    SciTech Connect

    Cairns, E.J.

    1992-03-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

  4. Taking the Grading Conversation Public

    ERIC Educational Resources Information Center

    Reeves, Douglas B.

    2011-01-01

    To manage effective grading reform, education leaders must engage teachers, parents, communities, and policymakers in a rational discussion about grading. Doug Reeves suggests that leaders start the conversation with a discussion of the principles on which all stakeholders can agree; make clear what will not change under the new grading policy; be…

  5. A Conversation with Edwin Shneidman

    ERIC Educational Resources Information Center

    Pestian, John

    2010-01-01

    This article is a transcript of a conversation that took place with Edwin Shneidman, PhD, on August 19, 2008. Recent advances in machine learning, particularly neurocognitive computing, have provided a fresh approach to the idea of using computers to analyze the language of the suicidal person. Here this notion and many others are discussed.

  6. Batteries: Beyond intercalation and conversion

    NASA Astrophysics Data System (ADS)

    Grimaud, Alexis

    2017-01-01

    Conventional positive electrode materials for lithium-ion batteries, such as intercalation and conversion compounds, feature a host structure to reversibly insert and conduct lithium ions. Now, electrochemically activated transition metal oxide-lithium fluoride composite materials are shown to be a promising class of positive electrodes.

  7. Turbulence and energy conversion research

    SciTech Connect

    Hutchinson, R.A.

    1985-07-01

    This report examines the role of fluid mechanics research (particularly turbulence research) in improving energy conversion systems. In this report two of the listed application areas are selected as examples: fluidization and cavitation. Research needs in general, and research possibilities for ECUT in particular, are examined.

  8. A conversation with Edwin Shneidman.

    PubMed

    Pestian, John

    2010-10-01

    This article is a transcript of a conversation that took place with Edwin Shneidman, PhD, on August 19, 2008. Recent advances in machine learning, particularly neurocognitive computing, have provided a fresh approach to the idea of using computers to analyze the language of the suicidal person. Here this notion and many others are discussed.

  9. Technology for satellite power conversion

    NASA Technical Reports Server (NTRS)

    Campbell, D. P.; Gouker, M. A.; Summers, C.; Gallagher, J. J.

    1984-01-01

    Techniques for satellite electromagnetic energy transfer and power conversion at millimeter and infrared wavelengths are discussed. The design requirements for rectenna receiving elements are reviewed for both coherent radiation sources and Earth thermal infrared emission. Potential power transmitters including gyrotrons, free electron lasers, and CO2 lasers are assessed along with the rectification properties of metal-oxide metal diode power converters.

  10. INDOOR EMISSIONS FROM CONVERSION VARNISHES

    EPA Science Inventory

    Conversion varnishes are two-component, acid-catalyzed varnishes that are commonly used to finish cabinets. They are valued for their water- and stain-resistance, as well as their appearance. They have been found, however, to contribute to indoor emissions of organic compounds. F...

  11. Coaching Conversations: Enacting Instructional Scaffolding

    ERIC Educational Resources Information Center

    Gibson, Sharan A.

    2011-01-01

    This study analyzed coaching conversations and interviews of four coach/teacher partnerships for specific ways in which kindergarten and first-grade teachers, and coaches, conceptualized instructional scaffolding for guided reading. Interview transcripts were coded for coaches' and teachers' specific hypotheses/ ideas regarding instructional…

  12. Ocean thermal energy conversion (OTEC)

    SciTech Connect

    Lockerby, R.W.

    1981-01-01

    Ocean thermal energy conversion (OTEC) is reviewed briefly. The two types of OTEC system (open and closed) are described and limitations are pointed out. A bibliography of 148 references on OTEC is given for the time period 1975 to 1980. Entries are arranged alphabetically according to the author's name. (MJJ)

  13. Ocean Thermal Energy Conversion (OTEC)

    NASA Technical Reports Server (NTRS)

    Lavi, A.

    1977-01-01

    Energy Research and Development Administration research progress in Ocean Thermal Energy Conversion (OTEC) is outlined. The development program is being focused on cost effective heat exchangers; ammonia is generally used as the heat exchange fluid. Projected costs for energy production by OTEC vary between $1000 to $1700 per kW.

  14. Conversation at the Intermediate Level

    ERIC Educational Resources Information Center

    Dunlop, Ian

    1975-01-01

    Discusses the use of free conversation, especially with regard to vocabulary. Recommends group discussion in the FL, using, at the intermediate level, limited, familiar vocabulary. At a higher level, words from a special technical vocabulary may be introduced, aurally and visually. A teaching example ("Traffic") is given with thorough…

  15. Direct-conversion receiver for HiperLAN2

    NASA Astrophysics Data System (ADS)

    Gu, Jian

    2001-11-01

    A direct conversion receiver is presented for HiperLAN2 system that uses Orthogonal Frequency Division Multiplexing (OFDM) as its modulation scheme with data rate up to 54 Mbits/second. The direct conversion scheme converts the RF signal directly into a complex low-pass equivalent signal represented by in- phase (I) and quadrature (Q) components or so called I-Q base- band signal without any Intermediate Frequency (IF) stages and expensive Surface-Acoustic-Wave (SAW) filters. However, for a direct conversion receiver there are many key issues to be solved. One of the most important issues is so-called I-Q imbalance caused by the mismatch between I channel and Q channel of the quadrature demodulator. The I-Q imbalance may include gain and group delay difference between the I channel and the Q channel at any frequency within the low-pass signal bandwidth. With the patent-pending IQ-BalancingTM technology and other proprietary technologies of 4D Connect, inc., the adverse effects of I-Q imbalance on the receiver performance can be removed. Fixed-point simulation results for sensitivity performance and interference performance are presented. Performance comparisons when severe I-Q imbalance is present are also given.

  16. Electrocatalysts for carbon dioxide conversion

    DOEpatents

    Masel, Richard I; Salehi-Khojin, Amin

    2015-04-21

    Electrocatalysts for carbon dioxide conversion include at least one catalytically active element with a particle size above 0.6 nm. The electrocatalysts can also include a Helper Catalyst. The catalysts can be used to increase the rate, modify the selectivity or lower the overpotential of electrochemical conversion of CO.sub.2. Chemical processes and devices using the catalysts also include processes to produce CO, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  17. Complexity matching in dyadic conversation.

    PubMed

    Abney, Drew H; Paxton, Alexandra; Dale, Rick; Kello, Christopher T

    2014-12-01

    Recent studies of dyadic interaction have examined phenomena of synchronization, entrainment, alignment, and convergence. All these forms of behavioral matching have been hypothesized to play a supportive role in establishing coordination and common ground between interlocutors. In the present study, evidence is found for a new kind of coordination termed complexity matching. Temporal dynamics in conversational speech signals were analyzed through time series of acoustic onset events. Timing in periods of acoustic energy was found to exhibit behavioral matching that reflects complementary timing in turn-taking. In addition, acoustic onset times were found to exhibit power law clustering across a range of timescales, and these power law functions were found to exhibit complexity matching that is distinct from behavioral matching. Complexity matching is discussed in terms of interactive alignment and other theoretical principles that lead to new hypotheses about information exchange in dyadic conversation and interaction in general.

  18. Coal conversion products Industrial applications

    NASA Technical Reports Server (NTRS)

    Warren, D.; Dunkin, J.

    1980-01-01

    The synfuels economic evaluation model was utilized to analyze cost and product economics of the TVA coal conversion facilities. It is concluded that; (1) moderate yearly future escalations ( 6%) in current natural gas prices will result in medium-Btu gas becoming competitive with natural gas at the plant boundary; (2) utilizing DRI price projections, the alternate synfuel products, except for electricity, will be competitive with their counterparts; (3) central site fuel cell generation of electricity, utilizing MBG, is economically less attractive than the other synthetic fuels, given projected price rises in electricity produced by other means; and (4) because of estimated northern Alabama synfuels market demands, existing conventional fuels, infrastructure and industrial synfuels retrofit problems, a diversity of transportable synfuels products should be produced by the conversion facility.

  19. Observation of Thermoacoustic Energy Conversion

    NASA Astrophysics Data System (ADS)

    Tashiro, Yusuke; Biwa, Tetsushi; Yazaki, Taichi

    In order to understand thermoacoustic phenomena from a point of view of thermodynamics, oscillating pressure, velocity and temperature were measured in the tube having a temperature gradient. By converting the measured Eulerian quantities to the Lagrangian quantities associated with a given gas parcel, we determined the local energy conversion rate per unit volume and time. The obtained data demonstrate the validity of the thermodynamic approach to thermoacoustic phenomena.

  20. Direct Energy Conversion Literature Abstracts

    DTIC Science & Technology

    1963-12-01

    for single and multiloop first in handy packages for use anywhere Carnot cycles. Parameters related to on earth or in space, and eventually in...by Various inorganic fluids which may be o F.X. Dobler, and others.306p., Feb.8,1962. potential value for energy conversion or (Prog. Rept.- First Q...during the first three months. background material is discussed, including thermodynamic cycle, heat transfer, compati- 4679 bility, and working

  1. Direct Energy Conversion Literature Abstracts

    DTIC Science & Technology

    1962-12-01

    3530-3533 4. Fusion ........................................................ 3534-3536 C. Solar Collection and Concentration...Cooley, W.C. SOLAR DIRECT-CONVERSION. 245p., New York, United Nations, 1961. POWER SYSTEMS. Inst. Radio Engra. Trans. MIL-6: 91-98, illus., Jan. j 1962...In ch.V entitled Fuel and Power Research, nuclear and solar energy are discussed, in A survey is made of the present status of general. technology of

  2. Materials for thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1988-01-01

    The field of thermoelectric energy conversion is reviewed from both a theoretical and an experimental standpoint. The basic theory is introduced and the thermodynamic and solid state views are compared. An overview of the development of thermoelectric materials is presented with particular emphasis being placed on the most recent developments in high-temperature semiconductors. A number of possible device applications are discussed and the successful use and suitability of these devices for space power is manifest.

  3. Conversion of heavy petroleum oils

    SciTech Connect

    Farcasiu, M.

    1982-03-02

    Heavy petroleum oils, such as vacuum resids, and heavy fractions of tar sands and shale oil, are partially converted to more volatile hydrocarbons by mixing with light aromatic hydrocarbons and treatment of the mixture with a friedel-crafts catalyst such as aluminum chloride. It is believed that the conversion found is essentially a transalkylation, I.E. The resid undergoes dealkylation with concurrent alkylation of the light aromatic hydrocarbon.

  4. Irradiation enhancement of biomass conversion

    NASA Astrophysics Data System (ADS)

    Smith, G. S.; Kiesling, H. E.; Galyean, M. L.; Bader, J. R.

    The vast supply of cellulosic agricultural residues and industrial by-products that is produced each year is a prospective resource of biomass suitable for conversion to useful products such as feedstock for the chemicals industry and feedstuffs for the livestock industry. Conversions of such biomass is poor at present, and utilization is inefficient, because of physio-chemical barriers to biological degradation and (or) anti-quality components such as toxicants that restrict biological usages. Improvements in biodegradability of ligno-cellulosic materials have been accomplished by gamma-ray and electron-beam irradiation at intermediate dosage (˜ 50 Mrad; .5 MGy); but applications of the technology have been hampered by questionable interpretations of results. Recent research with organic wastes such as sewage sludge and straw suggests opportunity for important applications of irradiation technology in enhancement of biomass conversion. Data from experiments using irradiated straw as feed for ruminants are presented and discussed in relation to research on prospective usage of sewage products as feed for ruminants. Findings are discussed in regard to prospective applications in industrial fermentation processes. Possible usage of irradiation technology for destruction of toxicants in exotic plants is considered in regard to prospective new feedstuffs.

  5. Hemicellulose conversion by anaerobic digestion

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Christopher, R.W.

    1982-01-01

    The digestibility of an aquatic biomass (water hyacinth), a land-based biomass (Coastal Bermuda grass), and a biomass-waste blend (a mixture of hyacinth, grass, MSW, and sludge) under various digestion conditions was studied. Anaerobic digestion of hemicellulose consists of the steps of enzymatic hydrolysis of hemicellulose to glucans, mannans, galactans, xylans, and arabans, and then to simple hexose and pentose sugars; production of C/sub 2/ and higher fatty acids from the simple sugars; conversion of higher fatty acids to acetate; and finally, production of methane and CO/sub 2/ from acetate, and CO/sub 2/ and hydrogen. The conversion of hemicellulose was higher under mesophilic conditions than those of cellulose or protein for all biomass test feeds, probably because the hemicellulose structure was more vulnerable to enzymatic attack than that of the lignocellulosic component. Cellulose conversion efficiencies at the mesophilic and thermophilic temperatures were about the same. However, hemicellulose was converted at a much lower efficiency than cellulose during thermophilic digestion - a situation that was the reverse of that observed at the mesophilic temperature. Cellulose was utilized in preference to hemicellulose during mesophilic digestion of nitrogen-supplemented Bermuda grass. It was speculated that Bermuda grass cellulose was converted at a higher efficiency than hemicellulose in the presence of external nitrogen because the metabolism of the breakdown product (glucose) of cellulose requires the least investment of enzymes and energy.

  6. Allocation of speech in conversation.

    PubMed

    Simon, Carsta; Baum, William M

    2017-03-01

    In a replication and extension of Conger and Killeen's (1974) widely cited demonstration of matching in conversations, we evaluated nine participants' allocation of speech and gaze to two conversational partners. German speakers participated in two 90-min sessions in which confederates uttered approval on independent variable-interval schedules. In one of the sessions, confederates uttered approval contingent upon and contiguous with eye contact whereas in the other session approval was uttered independent of the participant's gaze. Several measures of participants' verbal behavior were taken, including relative duration and rate of speech and gaze. These were compared to confederates' relative rate of approval and relative duration and rate of talk. The generalized matching equation was fitted to the various relations between participants' behavior and confederates' behavior. Conger and Killeen's results were not replicated; participants' response allocation did not show a systematic relation to the confederates' relative rate of approval. The strongest relations were to overall talk, rather than approval. In both conditions, the participant talked more to the confederate who talked less-inverse or antimatching. Participants' gaze showed the same inverse relation to the confederates' talk. Requiring gaze to be directed toward a confederate for delivery of approval made no difference in the results. The absence of a difference combined with prior research suggests that matching or antimatching in conversations is more likely due to induction than to reinforcement.

  7. Methanol conversion to higher hydrocarbons

    SciTech Connect

    Tabak, S.A.

    1994-12-31

    Several indirect options exist for producing chemicals and transportation fuels from coal, natural gas, or biomass. All involve an initial conversion step to synthesis gas (CO and H{sub 2}). Presently, there are two commercial technologies for converting syngas to liquids: Fischer-Tropsch, which yields a range of aliphatic hydrocarbons with molecular weights determined by Schulz-Flory kinetics, and methanol synthesis. Mobil`s diversity of technology for methanol conversion gives the methanol synthesis route flexibility for production of either gasoline, distillate or chemicals. Mobil`s ZSM-5 catalyst is the key in several processes for producing chemicals and transportation fuels from methanol: MTO for light olefins, MTG for gasoline, MOGD for distillates. The MTG process has been commercialized in New Zealand since 1985, producing one-third of the country`s gasoline supply, while MTO and MOGD have been developed and demonstrated at greater than 100 BPD scale. This paper will discuss recent work in understanding methanol conversion chemistry and the various options for its use.

  8. Frequency noise in frequency swept fiber laser.

    PubMed

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-04-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto- optical modulators and forward propagating Brillouin scattering appear in the spectrum.

  9. A frequency up-converting harvester based on internal resonance in 2-DOF nonlinear systems

    NASA Astrophysics Data System (ADS)

    Wu, Yipeng; Qiu, Jinhao; Ji, Hongli

    2016-11-01

    This paper reports the design and experimental testing of a novel frequency up- converting piezoelectric energy harvester. The harvester is firstly approximated as a 2-degree- of-freedom cubic nonlinear system instead of the general Duffing systems. A 1:3 internal resonance innovatively applied in the frequency up-conversion approach is thoroughly investigated. Finally, the theoretical dynamic model confirmed by the experimental results clearly shows the effect of the frequency up-conversion.

  10. An Experimental Investigation of the Effect of Altered Auditory Feedback on the Conversational Speech of Adults Who Stutter

    ERIC Educational Resources Information Center

    Lincoln, Michelle; Packman, Ann; Onslow, Mark; Jones, Mark

    2010-01-01

    Purpose: To investigate the impact on percentage of syllables stuttered of various durations of delayed auditory feedback (DAF), levels of frequency-altered feedback (FAF), and masking auditory feedback (MAF) during conversational speech. Method: Eleven adults who stuttered produced 10-min conversational speech samples during a control condition…

  11. Genomic and Population-Level Effects of Gene Conversion in Caenorhabditis Paralogs

    PubMed Central

    Katju, Vaishali; Bergthorsson, Ulfar

    2010-01-01

    Interlocus gene conversion, the nonreciprocal exchange of genetic material between genes, is facilitated by high levels of sequence identity between DNA sequences and has the dual effect of homogenizing intergenic sequences while increasing intragenic variation. Gene conversion can have important consequences for the evolution of paralogs subsequent to gene duplication, as well as result in misinterpretations regarding their evolution. We review the current state of research on gene conversion in paralogs within Caenorhabditis elegans and its congeneric species, including the relative rates of gene conversion, the range of observable conversion tracts, the genomic variables that strongly influence the frequency of gene conversion and its contribution to concerted evolution of multigene families. Additionally, we discuss recent studies that examine the phenotypic and population-genetic effects of interlocus gene conversion between the sex-determination locus fog-2 and its paralog ftr-1 in natural and experimental populations of C. elegans. In light of the limitations of gene conversion detection methods that rely solely on the statistical distribution of identical nucleotides between paralogs, we suggest that analyses of gene conversion in C. elegans take advantage of mutation accumulation experiments and sequencing projects of related Caenorhabditis species. PMID:24710096

  12. Molten Slag Would Boost Coal Conversion

    NASA Technical Reports Server (NTRS)

    Ferrall, J. F.

    1984-01-01

    Reactor increases residence time of uncovered char. Near-100percent carbon conversion achievable in reactor incorporating moltenslag bath. Slag maintains unconverted carbon impinging on surface at high temperatures for longer period of time, enhancing conversion.

  13. Interrogative suggestibility in patients with conversion disorders.

    PubMed

    Foong, J; Lucas, P A; Ron, M A

    1997-09-01

    We tested the hypothesis that increased interrogative suggestibility may contribute to the shaping and maintaining of conversions symptoms. Interrogative suggestibility was measured in 12 patients with conversion disorder and 10 control patients with confirmed neurological disease matched for age, premorbid intelligence, and as closely as possible in terms of their neurological symptoms to the patients with conversion disorder. Our observations do not support the contention that individual differences in interrogative suggestibility are of importance in the etiology of conversion disorders.

  14. A study of the conversion of ultrasonic energy and their transducers

    NASA Astrophysics Data System (ADS)

    Li, Q. L.; Wu, J.

    2017-01-01

    This paper essay offers a survey of research on interconvertibility of the conversion of ultrasonic energy with other energy, and their transducers, the conversion materials. Furthermore, it mainly gives piezoelectric ultrasonic transducer and piezoelectrical ultrasonic transducer material. Finally, some problems of ultrasonic energy and transducers, especially microelectronic materials and its acoustoelectric devices used for the ultrahigh-frequency (UHF) ultrasonic which need further research are pointed out.

  15. Evaluating Interpersonal Synchrony: Wavelet Transform Toward an Unstructured Conversation

    PubMed Central

    Fujiwara, Ken; Daibo, Ikuo

    2016-01-01

    This study examined whether interpersonal synchrony could be extracted using spectrum analysis (i.e., wavelet transform) in an unstructured conversation. Sixty-two female undergraduates were randomly paired and they engaged in a 6-min unstructured conversation. Interpersonal synchrony was evaluated by calculating the cross-wavelet coherence of the time-series movement data, extracted using a video-image analysis software. The existence of synchrony was tested using a pseudo-synchrony paradigm. In addition, the frequency at which the synchrony occurred and the distribution of the relative phase was explored. The results showed that the value of cross-wavelet coherence was higher in the experimental participant pairs than in the pseudo pairs. Further, the coherence value was higher in the frequency band under 0.5 Hz. These results support the validity of evaluating interpersonal synchron Behavioral mimicry and interpersonal syyby using wavelet transform even in an unstructured conversation. However, the role of relative phase was not clear; there was no significant difference between each relative-phase region. The theoretical contribution of these findings to the area of interpersonal coordination is discussed. PMID:27148125

  16. Evaluating Interpersonal Synchrony: Wavelet Transform Toward an Unstructured Conversation.

    PubMed

    Fujiwara, Ken; Daibo, Ikuo

    2016-01-01

    This study examined whether interpersonal synchrony could be extracted using spectrum analysis (i.e., wavelet transform) in an unstructured conversation. Sixty-two female undergraduates were randomly paired and they engaged in a 6-min unstructured conversation. Interpersonal synchrony was evaluated by calculating the cross-wavelet coherence of the time-series movement data, extracted using a video-image analysis software. The existence of synchrony was tested using a pseudo-synchrony paradigm. In addition, the frequency at which the synchrony occurred and the distribution of the relative phase was explored. The results showed that the value of cross-wavelet coherence was higher in the experimental participant pairs than in the pseudo pairs. Further, the coherence value was higher in the frequency band under 0.5 Hz. These results support the validity of evaluating interpersonal synchron Behavioral mimicry and interpersonal syyby using wavelet transform even in an unstructured conversation. However, the role of relative phase was not clear; there was no significant difference between each relative-phase region. The theoretical contribution of these findings to the area of interpersonal coordination is discussed.

  17. 47 CFR 80.761 - Conversion graphs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Conversion graphs. 80.761 Section 80.761... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.761 Conversion graphs. The following graphs must be employed where conversion from one to the other of the indicated types of units...

  18. 47 CFR 80.761 - Conversion graphs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Conversion graphs. 80.761 Section 80.761... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.761 Conversion graphs. The following graphs must be employed where conversion from one to the other of the indicated types of units...

  19. 47 CFR 80.761 - Conversion graphs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Conversion graphs. 80.761 Section 80.761... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.761 Conversion graphs. The following graphs must be employed where conversion from one to the other of the indicated types of units...

  20. 47 CFR 80.761 - Conversion graphs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Conversion graphs. 80.761 Section 80.761... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.761 Conversion graphs. The following graphs must be employed where conversion from one to the other of the indicated types of units...

  1. 47 CFR 80.761 - Conversion graphs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Conversion graphs. 80.761 Section 80.761... MARITIME SERVICES Standards for Computing Public Coast Station VHF Coverage § 80.761 Conversion graphs. The following graphs must be employed where conversion from one to the other of the indicated types of units...

  2. 5 CFR 536.303 - Geographic conversion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... after geographic conversion is the employee's existing payable rate of basic pay in effect immediately before the action. (b) Geographic conversion when a retained rate employee's official worksite is changed... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Geographic conversion. 536.303...

  3. 5 CFR 536.303 - Geographic conversion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... after geographic conversion is the employee's existing payable rate of basic pay in effect immediately before the action. (b) Geographic conversion when a retained rate employee's official worksite is changed... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Geographic conversion. 536.303...

  4. Retrospective Conversion of Three Library Collections.

    ERIC Educational Resources Information Center

    Johnson, Carolyn A.

    1982-01-01

    Reports on the retrospective conversion via OCLC of cataloging for three library collections at the University of South Carolina--the main, rare book, and historical collections. Backgrounds of the collections, conversion procedures, determinants of conversion rates, and cost factors are discussed. (Author/JL)

  5. Adaptive Feedback Improving Learningful Conversations at Workplace

    ERIC Educational Resources Information Center

    Gaeta, Matteo; Mangione, Giuseppina Rita; Miranda, Sergio; Orciuoli, Francesco

    2013-01-01

    This work proposes the definition of an Adaptive Conversation-based Learning System (ACLS) able to foster computer-mediated tutorial dialogues at the workplace in order to increase the probability to generate meaningful learning during conversations. ACLS provides a virtual assistant selecting the best partner to involve in the conversation and…

  6. The Teacher and the Conversational Situation

    ERIC Educational Resources Information Center

    Fenn, Peter

    1977-01-01

    Cites a typical classroom "pseudo-conversation," showing how German students of English sound stiff and clumsy when conversing with English-speaking partners. This is blamed partly on the teacher's behavior. The example is then expanded into a "communicative exchange." In teaching conversation, manner is seen as more important…

  7. Teaching Casual Conversation: The Issue of Simplification.

    ERIC Educational Resources Information Center

    Slade, Diana; Gardner, Rod

    This paper focuses on the issue of whether pedagogical mediation will facilitate the acquisition of conversational skills. It argues that it is possible to describe casual conversation, that it has a grammatical structure, and that it is of benefit to English-as-a-Second-Language (ESL) learners for the structure of conversation to be explicitly…

  8. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  9. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Robert J.; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This viewgraph presentation reports on the development of a high power 780 nm laser suitable for space applications of laser cooling. A possible solution is to use frequency doubling of high power 1560 nm telecom lasers. The presentation shows a diagram of the frequency conversion, and a graph of the second harmonic generation in one crystal, and the use of the cascading crystals. Graphs show the second harmonic power as a function of distance between crystals, second harmonic power vs. pump power, tunability of laser systems.

  10. Conversion gain and noise of niobium superconducting hot-electron-mixers

    NASA Technical Reports Server (NTRS)

    Ekstrom, Hans; Karasik, Boris S.; Kollberg, Erik L.; Yngvesson, Sigfrid

    1995-01-01

    A study has been done of microwave mixing at 20 GHz using the nonlinear (power dependent) resistance of thin niobium strips in the resistive state. Our experiments give evidence that electron-heating is the main cause of the nonlinear phenomenon. Also a detailed phenomenological theory for the determination of conversion properties is presented. This theory is capable of predicting the frequency-conversion loss rather accurately for arbitrary bias by examining the I-V-characteristic. Knowing the electron temperature relaxation time, and using parameters derived from the I-V-characteristic also allows us to predict the -3 dB IF bandwidth. Experimental results are in excellent agreement with the theoretical predictions. The requirements on the mode of operation and on the film parameters for minimizing the conversion loss (and even achieving conversion gain) are discussed in some detail. Our measurements demonstrate an intrinsic conversion loss as low as 1 dB. The maximum IF frequency defined for -3 dB drop in conversion gain, is about 80 MHz. Noise measurements indicate a device output noise temperature of about 50 K and SSB mixer noise temperature below 250 K. This type of mixer is considered very promising for use in low-noise heterodyne receivers at THz frequencies.

  11. Algal Energy Conversion and Capture

    NASA Astrophysics Data System (ADS)

    Hazendonk, P.

    2015-12-01

    We address the potential for energy conversions and capture for: energy generation; reduction in energy use; reduction in greenhouse gas emissions; remediation of water and air pollution; protection and enhancement of soil fertility. These processes have the potential to sequester carbon at scales that may have global impact. Energy conversion and capture strategies evaluate energy use and production from agriculture, urban areas and industries, and apply existing and emerging technologies to reduce and recapture energy embedded in waste products. The basis of biocrude production from Micro-algal feedstocks: 1) The nutrients from the liquid fraction of waste streams are concentrated and fed into photo bioreactors (essentially large vessels in which microalgae are grown) along with CO2 from flue gasses from down stream processes. 2) The algae are processed to remove high value products such as proteins and beta-carotenes. The advantage of algae feedstocks is the high biomass productivity is 30-50 times that of land based crops and the remaining biomass contains minimal components that are difficult to convert to biocrude. 3) The remaining biomass undergoes hydrothermal liquefaction to produces biocrude and biochar. The flue gasses of this process can be used to produce electricity (fuel cell) and subsequently fed back into the photobioreactor. The thermal energy required for this process is small, hence readily obtained from solar-thermal sources, and furthermore no drying or preprocessing is required keeping the energy overhead extremely small. 4) The biocrude can be upgraded and refined as conventional crude oil, creating a range of liquid fuels. In principle this process can be applied on the farm scale to the municipal scale. Overall, our primary food production is too dependent on fossil fuels. Energy conversion and capture can make food production sustainable.

  12. Conversion disorder: a problematic diagnosis.

    PubMed

    Nicholson, Timothy R J; Stone, Jon; Kanaan, Richard A A

    2011-11-01

    The diagnosis of conversion disorder is problematic. Since doctors have conceptually and practically differentiated the symptoms from neurological ('organic') disease it has been presumed to be a psychological disorder, but the psychological mechanism, and how this differs from feigning (conscious simulation), has remained elusive. Although misdiagnosis of neurological disease as conversion disorder is uncommon, it remains a concern for clinicians, particularly for psychiatrists who may be unaware of the positive ways in which neurologists can exclude organic disease. The diagnosis is anomalous in psychiatry in that current diagnostic systems require that feigning is excluded and that the symptoms can be explained psychologically. In practice, feigning is very difficult to either disprove or prove, and a psychological explanation cannot always be found. Studies of childhood and adult psychological precipitants have tended to support the relevance of stressful life events prior to symptom onset at the group level but they are not found in a substantial proportion of cases. These problems highlight serious theoretical and practical issues not just for the current diagnostic systems but for the concept of the disorder itself. Psychology, physiology and functional imaging techniques have been used in attempts to elucidate the neurobiology of conversion disorder and to differentiate it from feigning, but while intriguing results are emerging they can only be considered preliminary. Such work looks to a future that could refine our understanding of the disorder. However, until that time, the formal diagnostic requirement for associated psychological stressors and the exclusion of feigning are of limited clinical value. Simplified criteria are suggested which will also encourage cooperation between neurology and psychiatry in the management of these patients.

  13. Low conversion ratio fuel studies.

    SciTech Connect

    Smith, M. A.

    2006-02-28

    Recent studies on TRU disposition in fast reactors indicated viable reactor performance for a sodium cooled low conversion ratio reactor design. Additional studies have been initiated to refine the earlier work and consider the feasibility of alternate fuel forms such as nitride and oxide fuel (rather than metal fuel). These alternate fuel forms may have significant impacts upon the burner design and the safety behavior. The work performed thus far has focused on compiling the necessary fuel form property information and refinement of the physics models. For this limited project, the burner design and performance using nitride fuel will be assessed.

  14. Conversion of raw carbonaceous fuels

    DOEpatents

    Cooper, John F.

    2007-08-07

    Three configurations for an electrochemical cell are utilized to generate electric power from the reaction of oxygen or air with porous plates or particulates of carbon, arranged such that waste heat from the electrochemical cells is allowed to flow upwards through a storage chamber or port containing raw carbonaceous fuel. These configurations allow combining the separate processes of devolatilization, pyrolysis and electrochemical conversion of carbon to electric power into a single unit process, fed with raw fuel and exhausting high BTU gases, electric power, and substantially pure CO.sub.2 during operation.

  15. Raster to Lineal Conversion Software.

    DTIC Science & Technology

    1980-10-01

    Acceso B-i APPENDIX C NTIS GAIC-i r-l TAB U1nunno~Ced 1 just if icai DistribUtionI _Availabilit oe --- Avail and/or _it Spe ci I pca LIST OF FIGURES...shortcomings of the existing Raster to Lineal Conversion Software, and, secondly, to design and implement output modules to provide multiple output formats...the RAPS scanner and to provide flexibility. This would result in a more useful system, one that could provide multiple types of output from multiple

  16. Formation of alcohol conversion catalysts

    DOEpatents

    Wachs, Israel E.; Cai, Yeping

    2001-01-01

    The method of the present invention involves a composition containing an intimate mixture of (a) metal oxide support particles and (b) a catalytically active metal oxide from Groups VA, VIA, or VIIA, its method of manufacture, and its method of use for converting alcohols to aldehydes. During the conversion process, catalytically active metal oxide from the discrete catalytic metal oxide particles migrates to the oxide support particles and forms a monolayer of catalytically active metal oxide on the oxide support particle to form a catalyst composition having a higher specific activity than the admixed particle composition.

  17. Conversion from tacrolimus to cyclosporine--a based immunosuppression following liver transplantation.

    PubMed

    Doria, Cataldo; Jain, Ashok Kumar B; Scott, Victor L; Gruttadauria, Salvatore; Marino, Ignazio R; Doyle, Howard R; Fung, John J

    2003-06-01

    We examined the frequency, reasons and outcome after conversion from Tacrolimus to Cyclosporine A. From August 1989 to December 1992, 1000 consecutive liver transplantation patients were studied, which included 834 adults (age>18 yr.) and 166 children with mean follow-up of 77 months (range 56 to 96). A prospectively populated electronic database was queried to identify patients that underwent conversion, the clinical indication and outcomes. Thirty-seven out of 834 adult recipients (4.43%), mean age of 48.4+/-12.9 years, 19 male (51.35%) and 18 females (48.64%) required conversion from Tacrolimus to Cyclosporine A baseline immunosuppressive therapy. No pediatric patient required conversion. The mean time interval from liver transplantation to Cyclosporine A conversion was 443.45+/-441.44 days (range 22 to 1641). The clinical indications for conversion included: 20 neurological (54%), 6 gastrointestinal (16%), 5 hematological (14%), and 6 other (16%) scenarios. Seven of the 37 patients (18.9%) died. The causes of death were multi-organ failure (2), sepsis (2), pancreatitis (1), hepatic failure due to relapse of ethanol abuse (1), and unknown cause (1). Nine out of 37 patients (24.32%) had to be reconverted to Tacrolimus (mean 282.22+/-499.79 days; range 15 to 1583 day with a median of 135) after institution of Cyclosporine A; none showed recurrence of the original symptoms. The reasons for these re-conversions were acute cellular rejection (44%, n=4), chronic rejection (11%, n=1), increased hepatic enzymes (33%, n=3) and progressively worsening neurological symptoms (11%, n=1). The frequency of conversion from Tacrolimus to Cyclosporine A was 4.43%. Conversion is safe and efficacious if done in a controlled setting. Additionally, re-conversion to Tacrolimus for lack of efficacy of Cyclosporine A did not appear to be associated with a recurrence of the condition that caused the initial switch.

  18. Biomass conversion processes for energy and fuels

    NASA Astrophysics Data System (ADS)

    Sofer, S. S.; Zaborsky, O. R.

    The book treats biomass sources, promising processes for the conversion of biomass into energy and fuels, and the technical and economic considerations in biomass conversion. Sources of biomass examined include crop residues and municipal, animal and industrial wastes, agricultural and forestry residues, aquatic biomass, marine biomass and silvicultural energy farms. Processes for biomass energy and fuel conversion by direct combustion (the Andco-Torrax system), thermochemical conversion (flash pyrolysis, carboxylolysis, pyrolysis, Purox process, gasification and syngas recycling) and biochemical conversion (anaerobic digestion, methanogenesis and ethanol fermentation) are discussed, and mass and energy balances are presented for each system.

  19. Biomass thermochemical conversion program: 1987 annual report

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1988-01-01

    The objective of the Biomass Thermochemical Conversion Program is to generate a base of scientific data and conversion process information that will lead to establishment of cost-effective processes for conversion of biomass resources into clean fuels. To accomplish this objective, in fiscal year 1987 the Thermochemical Conversion Program sponsored research activities in the following four areas: Liquid Hydrocarbon Fuels Technology; Gasification Technology; Direct Combustion Technology; Program Support Activities. In this report an overview of the Thermochemical Conversion Program is presented. Specific research projects are then described. Major accomplishments for 1987 are summarized.

  20. Biomass thermochemical conversion program. 1985 annual report

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1986-01-01

    Wood and crop residues constitute a vast majority of the biomass feedstocks available for conversion, and thermochemical processes are well suited for conversion of these materials. The US Department of Energy (DOE) is sponsoring research on this conversion technology for renewable energy through its Biomass Thermochemical Conversion Program. The Program is part of DOE's Biofuels and Municipal Waste Technology Division, Office of Renewable Technologies. This report briefly describes the Thermochemical Conversion Program structure and summarizes the activities and major accomplishments during fiscal year 1985. 32 figs., 4 tabs.

  1. Static conversion systems. [for space power reactors

    NASA Technical Reports Server (NTRS)

    Ewell, R.; Mondt, J.

    1985-01-01

    Historically, all space power systems that have actually flown in space have relied on static energy conversion technology. Thus, static conversion is being considered for space nuclear power systems as well. There are four potential static conversion technologies which should be considered. These include: the alkali metal thermoelectric converter (AMTEC), the thermionic converter, the thermoelectric converter, and the thermophotovoltaic converter (TPV). These four conversion technologies will be described in brief detail along with their current status and development needs. In addition, the systems implications of using each of these conversion technologies with a space nuclear reactor power system will be evaluated and some comparisons made.

  2. Advanced Coal Conversion Process Demonstration Project

    SciTech Connect

    Not Available

    1992-04-01

    Western Energy Company (WECO) was selected by the Department of Energy (DOE) to demonstrate the Advanced Coal Conversion Process (ACCP) which upgrades low rank coals into high Btu, low sulfur, synthetic bituminous coal. As specified in the Corporate Agreement, RSCP is required to develop an Environmental Monitoring Plan (EMP) which describes in detail the environmental monitoring activities to be performed during the project execution. The purpose of the EMP is to: (1) identify monitoring activities that will be undertaken to show compliance to applicable regulations, (2) confirm the specific environmental impacts predicted in the National Environmental Policy Act documentation, and (3) establish an information base of the assessment of the environmental performance of the technology demonstrated by the project. The EMP specifies the streams to be monitored (e.g. gaseous, aqueous, and solid waste), the parameters to be measured (e.g. temperature, pressure, flow rate), and the species to be analyzed (e.g. sulfur compounds, nitrogen compounds, trace elements) as well as human health and safety exposure levels. The operation and frequency of the monitoring activities is specified, as well as the timing for the monitoring activities related to project phase (e.g. preconstruction, construction, commissioning, operational, post-operational). The EMP is designed to assess the environmental impacts and the environmental improvements resulting from construction and operation of the project.

  3. Photochemical conversion of solar energy.

    PubMed

    Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

    2008-01-01

    Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago.

  4. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  5. Radiation energy conversion in space

    NASA Technical Reports Server (NTRS)

    Billman, K. W.

    1979-01-01

    Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.

  6. [Neurology of hysteria (conversion disorder)].

    PubMed

    Sonoo, Masahiro

    2014-07-01

    Hysteria has served as an important driving force in the development of both neurology and psychiatry. Jean Martin Charcot's devotion to mesmerism for treating hysterical patients evoked the invention of psychoanalysis by Sigmund Freud. Meanwhile, Joseph Babinski took over the challenge to discriminate between organic and hysterical patients from Charcot and found Babinski's sign, the greatest milestone in modern neurological symptomatology. Nowadays, the usage of the term hysteria is avoided. However, new terms and new classifications are complicated and inconsistent between the two representative taxonomies, the DSM-IV and ICD-10. In the ICD-10, even the alternative term conversion disorder, which was becoming familiar to neurologists, has also disappeared as a group name. The diagnosis of hysteria remains important in clinical neurology. Extensive exclusive diagnoses and over investigation, including various imaging studies, should be avoided because they may prolong the disease course and fix their symptoms. Psychological reasons that seem to explain the conversion are not considered reliable. Positive neurological signs suggesting nonorganic etiologies are the most reliable measures for diagnosing hysteria, as Babinski first argued. Hysterical paresis has several characteristics, such as giving-way weakness or peculiar distributions of weakness. Signs to uncover nonorganic paresis utilizing synergy include Hoover's test and the Sonoo abductor test.

  7. Biological conversion of synthesis gas

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. R. rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H[sub 2]0 [yields] CO[sub 2] + H[sub 2]. C. thiosulfatophilum is also a H[sub 2]S and COS to elemental sulfur. The growth of R. rubrum may be satisfactorily carried out at 25[degree] and 30[degree]C, while CO uptake and thus the conversion of CO best occurs at temperatures of either 30[degree], 32[degree] or 34[degree]C. The rate of conversion of COs and H[sub 2]O to CO[sub 2] and H[sub 2]S may be modeled by a first order rate expression. The rate constant at 30[degree]C was found to be 0.243 h[sup [minus]1]. The growth of C. thiosulfatophilum may be modeled in terms of incoming light intensity using a Monod equation: [mu] = [sub 351] + I[sub o]/[sup 0.152]I[sub o]. Comparisons of the growth of R. rubrum and C. thiosulfatophilum shows that the specific growth rate of C. thiosulfatophilum is much higher at a given light intensity.

  8. Bilingualism Accentuates Children's Conversational Understanding

    PubMed Central

    Siegal, Michael; Surian, Luca; Matsuo, Ayumi; Geraci, Alessandra; Iozzi, Laura; Okumura, Yuko; Itakura, Shoji

    2010-01-01

    Background Although bilingualism is prevalent throughout the world, little is known about the extent to which it influences children's conversational understanding. Our investigation involved children aged 3–6 years exposed to one or more of four major languages: English, German, Italian, and Japanese. In two experiments, we examined the children's ability to identify responses to questions as violations of conversational maxims (to be informative and avoid redundancy, to speak the truth, be relevant, and be polite). Principal Findings In Experiment 1, with increasing age, children showed greater sensitivity to maxim violations. Children in Italy who were bilingual in German and Italian (with German as the dominant language L1) significantly outperformed Italian monolinguals. In Experiment 2, children in England who were bilingual in English and Japanese (with English as L1) significantly outperformed Japanese monolinguals in Japan with vocabulary age partialled out. Conclusions As the monolingual and bilingual groups had a similar family SES background (Experiment 1) and similar family cultural identity (Experiment 2), these results point to a specific role for early bilingualism in accentuating children's developing ability to appreciate effective communicative responses. PMID:20140246

  9. Fast Pairwise Conversion of Supernova Neutrinos: A Dispersion Relation Approach

    NASA Astrophysics Data System (ADS)

    Izaguirre, Ignacio; Raffelt, Georg; Tamborra, Irene

    2017-01-01

    Collective pair conversion νeν¯ e↔νxν¯ x by forward scattering, where x =μ or τ , may be generic for supernova neutrino transport. Depending on the local angular intensity of the electron lepton number carried by neutrinos, the conversion rate can be "fast," i.e., of the order of √{2 }GF(nνe-nν¯e)≫Δ matm2/2 E . We present a novel approach to understand these phenomena: a dispersion relation for the frequency and wave number (Ω ,K ) of disturbances in the mean field of νeνx flavor coherence. Runaway solutions occur in "dispersion gaps," i.e., in "forbidden" intervals of Ω and/or K where propagating plane waves do not exist. We stress that the actual solutions also depend on the initial and/or boundary conditions, which need to be further investigated.

  10. Active tunable plasmonically induced polarization conversion in the THz regime

    NASA Astrophysics Data System (ADS)

    Ling, Furi; Yao, Gang; Yao, Jianquan

    2016-10-01

    A plasmon-induced polarization conversion (PIPC) structure based on periodically patterned graphene was demonstrated in the THz regime. By varying the Fermi level of two connected T-shape graphene strips through the electrostatic gating, the peak frequency and the group index in the transparency window can be tuned, which is good agreement with the coupled Lorentz oscillator model. Due to interference between two polarization selective graphene plasmonic resonances coexisting in the planar metamaterial, polarization conversion can be achieved. The linearly polarized THz wave can be converted to elliptically and right circularly polarized THz wave through varying the relaxation time of electrons in graphene. This novel chip-scale active terahertz device promises essential application opportunities in terahertz sensing and terahertz communications.

  11. Mode Conversion Heating Scenarios for the National Compact Stellarator Experiment

    SciTech Connect

    Majeski, R.; Wilson, J.R.; and Zarnstorff, M.

    2001-05-18

    Radio-frequency heating scenarios for the National Compact Stellarator eXperiment (NCSX) are considered. The focus here is on mode conversion from the fast to the slow ion Bernstein wave as either an electron or ''bulk'' ion heating technique, using a high-field side launch to directly access the ion-ion hybrid layer. Modeling for the planned parameters of NCSX [R(subscript ave) {approximately} 1.4 m, a(subscript ave) {approximately} 0.4 m, B(subscript T)(0) {approximately} 1.2-2 T, n(subscript e)(0) {approximately} 2-5 x 10(superscript19) m(superscript -3), T(subscript e)(0) {approximately} T(subscript i)(0) {approximately} 1-2 keV] for mode conversion in D-H and D-3He plasmas is presented. Possible types of high-field side antennas are also briefly discussed.

  12. Active tunable plasmonically induced polarization conversion in the THz regime

    PubMed Central

    Ling, Furi; Yao, Gang; Yao, Jianquan

    2016-01-01

    A plasmon-induced polarization conversion (PIPC) structure based on periodically patterned graphene was demonstrated in the THz regime. By varying the Fermi level of two connected T-shape graphene strips through the electrostatic gating, the peak frequency and the group index in the transparency window can be tuned, which is good agreement with the coupled Lorentz oscillator model. Due to interference between two polarization selective graphene plasmonic resonances coexisting in the planar metamaterial, polarization conversion can be achieved. The linearly polarized THz wave can be converted to elliptically and right circularly polarized THz wave through varying the relaxation time of electrons in graphene. This novel chip-scale active terahertz device promises essential application opportunities in terahertz sensing and terahertz communications. PMID:27734912

  13. Biomass Thermochemical Conversion Program: 1986 annual report

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1987-01-01

    Wood and crop residues constitute a vast majority of the biomass feedstocks available for conversion, and thermochemical processes are well suited for conversion of these materials. Thermochemical conversion processes can generate a variety of products such as gasoline hydrocarbon fuels, natural gas substitutes, or heat energy for electric power generation. The US Department of Energy is sponsoring research on biomass conversion technologies through its Biomass Thermochemical Conversion Program. Pacific Northwest Laboratory has been designated the Technical Field Management Office for the Biomass Thermochemical Conversion Program with overall responsibility for the Program. This report briefly describes the Thermochemical Conversion Program structure and summarizes the activities and major accomplishments during fiscal year 1986. 88 refs., 31 figs., 5 tabs.

  14. Gene Conversion in Human Genetic Disease

    PubMed Central

    Chen, Jian-Min; Férec, Claude; Cooper, David N.

    2010-01-01

    Gene conversion is a specific type of homologous recombination that involves the unidirectional transfer of genetic material from a ‘donor’ sequence to a highly homologous ‘acceptor’. We have recently reviewed the molecular mechanisms underlying gene conversion, explored the key part that this process has played in fashioning extant human genes, and performed a meta-analysis of gene-conversion events known to have caused human genetic disease. Here we shall briefly summarize some of the latest developments in the study of pathogenic gene conversion events, including (i) the emerging idea of minimal efficient sequence homology (MESH) for homologous recombination, (ii) the local DNA sequence features that appear to predispose to gene conversion, (iii) a mechanistic comparison of gene conversion and transient hypermutability, and (iv) recently reported examples of pathogenic gene conversion events. PMID:24710102

  15. Difference-frequency combs in cold atom physics

    NASA Astrophysics Data System (ADS)

    Kliese, Russell; Hoghooghi, Nazanin; Puppe, Thomas; Rohde, Felix; Sell, Alexander; Zach, Armin; Leisching, Patrick; Kaenders, Wilhelm; Keegan, Niamh C.; Bounds, Alistair D.; Bridge, Elizabeth M.; Leonard, Jack; Adams, Charles S.; Cornish, Simon L.; Jones, Matthew P. A.

    2016-12-01

    Optical frequency combs provide the clockwork to relate optical frequencies to radio frequencies. Hence, combs allow optical frequencies to be measured with respect to a radio frequency where the accuracy is limited only by the reference signal. In order to provide a stable link between the radio and optical frequencies, the two parameters of the frequency comb must be fixed: the carrier envelope offset frequency, f ceo, and the pulse repetition-rate, f rep. We have developed the first optical frequency comb based on difference frequency generation (DFG) that eliminates f ceo by design — specifically tailored for applications in cold atom physics. An f ceo-free spectrum at 1550 nm is generated from a super continuum spanning more than an optical octave. Established amplification and frequency conversion techniques based on reliable telecom fibre technology allow the generation of multiple wavelength outputs. The DFG comb is a convenient tool to both stabilise laser sources and accurately measure optical frequencies in Rydberg experiments and more generally in quantum optics. In this paper we discuss the frequency comb design, characterization, and optical frequency measurement of Strontium Rydberg states. The DFG technique allows for a compact and robust, passively f ceo stable frequency comb significantly improving reliability in practical applications.

  16. The role of amplitude-to-phase conversion in the generation of oscillator flicker phase noise

    NASA Technical Reports Server (NTRS)

    Hearn, C. P.

    1985-01-01

    The role of amplitude-to-phase conversion as a factor in feedback oscillator flicker phase noise is examined. A limiting stage consisting of parallel-connected opposite polarity diodes operating in a circuit environment contining reactance is shown to exhibit amplitude-to-phase conversion. This mechanism coupled with resistive upconversion provides an indirect route for very low frequency flicker noise to be transferred into the phase of an oscillator signal. It is concluded that this effect is more significant in the lower frequency regimes where the onlinear reactances associated with active devices are overwhelmed by linear reactive elements.

  17. Stimulated low frequency Raman scattering in cupric oxide nanoparticles water suspension

    NASA Astrophysics Data System (ADS)

    Averyushkin, A. S.; Baranov, A. N.; Bulychev, N. A.; Kazaryan, M. A.; Kudryavtseva, A. D.; Strokov, M. A.; Tcherniega, N. V.; Zemskov, K. I.

    2017-04-01

    Cupric oxide nanoparticles with average size of 213.2 nm, were synthesized in acoustoplasma discharge for investigating their vibrational properties. The low-frequency acoustic mode in cupric oxide (CuO) nanoparticles has been studied by stimulated low-frequency Raman scattering (SLFRS). SLFRS conversion efficiency, threshold and frequency shift of the scattered light are measured.

  18. Frequency Comb Cooling Project

    DTIC Science & Technology

    2014-03-18

    frequency combs ). Recently the power and spectral coverage of frequency combs have grown considerably with projected 1. REPORT DATE (DD-MM-YYYY) 4. TITLE...Aug-2011 18-May-2012 Approved for Public Release; Distribution Unlimited Final report on frequency comb cooling project The views, opinions and/or... frequency combs ). Recently the power and spectral coverage of frequency combs have grown considerably with projected average powers above 10 kW. We

  19. Thermodynamics fundamentals of energy conversion

    NASA Astrophysics Data System (ADS)

    Dan, Nicolae

    The work reported in the chapters 1-5 focuses on the fundamentals of heat transfer, fluid dynamics, thermodynamics and electrical phenomena related to the conversion of one form of energy to another. Chapter 6 is a re-examination of the fundamental heat transfer problem of how to connect a finite-size heat generating volume to a concentrated sink. Chapter 1 extends to electrical machines the combined thermodynamics and heat transfer optimization approach that has been developed for heat engines. The conversion efficiency at maximum power is 1/2. When, as in specific applications, the operating temperature of windings must not exceed a specified level, the power output is lower and efficiency higher. Chapter 2 addresses the fundamental problem of determining the optimal history (regime of operation) of a battery so that the work output is maximum. Chapters 3 and 4 report the energy conversion aspects of an expanding mixture of hot particles, steam and liquid water. At the elemental level, steam annuli develop around the spherical drops as time increases. At the mixture level, the density decreases while the pressure and velocity increases. Chapter 4 describes numerically, based on the finite element method, the time evolution of the expanding mixture of hot spherical particles, steam and water. The fluid particles are moved in time in a Lagrangian manner to simulate the change of the domain configuration. Chapter 5 describes the process of thermal interaction between the molten material and water. In the second part of the chapter the model accounts for the irreversibility due to the flow of the mixture through the cracks of the mixing vessel. The approach presented in this chapter is based on exergy analysis and represents a departure from the line of inquiry that was followed in chapters 3-4. Chapter 6 shows that the geometry of the heat flow path between a volume and one point can be optimized in two fundamentally different ways. In the "growth" method the

  20. Dynamic conversion of optical modes in magnetic garnet films induced by resonances of periodic stripe domains

    NASA Astrophysics Data System (ADS)

    Winkler, H. P.; Doetsch, H.; Luehrmann, B.; Sure, S.

    1994-09-01

    Magnetic garnet films of composition (Y,Bi)3(Fe,Al)5O12 are grown by liquid phase epitaxy on (111) oriented substrates of Gd3Ga5O12. They support periodic lattices of parallel stripe domains. A simple strip antenna is used to excite the domain wall resonance and the two branches of the domain resonance in the frequency range up to 5 GHz. The resonance frequencies and the dynamic components of the magnetization are calculated using a hybridization model. Good agreement between calculated and measured resonance frequencies is obtained if the quality factor of the film is larger than 0.6. Optical modes are coupled into the waveguiding film. The excited domain resonances cause dynamic conversion of transverse electric and transverse magnetic modes by the Faraday and the Cotton-Mouton effects. Mode coupling and conversion are calculated by the perturbation theory. The dynamic conversion efficiencies are measured at the fundamental and the first harmonic frequency and at zero diffraction order as a function of the static induction applied in the film plane parallel to the stripes. Conversion efficiencies up to 18% are achieved at a frequency of 2.8 GHz. From the experimental data the precession angles are derived.

  1. Photoelectrochemical based direct conversion systems

    SciTech Connect

    Kocha, S.; Arent, D.; Peterson, M.

    1995-09-01

    The goal of this research is to develop a stable, cost effective, photoelectrochemical based system that will split water upon illumination, producing hydrogen and oxygen directly, using sunlight as the only energy input. This type of direct conversion system combines a photovoltaic material and an electrolyzer into a single monolithic device. We report on our studies of two multifunction multiphoton photoelectrochemical devices, one based on the ternary semiconductor gallium indium phosphide, (GaInP{sub 2}), and the other one based on amorphous silicon carbide. We also report on our studies of the solid state surface treatment of GaInP{sub 2} as well as our continuing effort to develop synthetic techniques for the attachment of transition metal complexes to the surface of semiconductor electrodes. All our surface studies are directed at controlling the interface energetics and forming stable catalytic surfaces.

  2. Conversation Simulation and Sensible Surprises

    NASA Astrophysics Data System (ADS)

    Hutchens, Jason L.

    I have entered the Loebner Prize five times, winning the "most humanlike program" category in 1996 with a surly ELIZA-clone named HeX, but failed to repeat the performance in subsequent years with more sophisticated techniques. Whether this is indicative of an unanticipated improvement in "conversation simulation" technology, or whether it highlights the strengths of ELIZA-style trickery, is as an exercise for the reader. In 2000, I was invited to assume the role of Chief Scientist at Artificial Intelligence Ltd. (Ai) on a project inspired by the advice given by Alan Turing in the final section of his classic paper - our quest was to build a "child machine" that could learn and use language from scratch. In this chapter, I will discuss both of these experiences, presenting my thoughts regarding the Chinese Room argument and Artificial Intelligence (AI) in between.

  3. Ocean thermal-energy conversion

    NASA Astrophysics Data System (ADS)

    Ford, G.; Niblett, C.; Walker, L.

    1983-03-01

    The principles underlying ocean thermal-energy conversion (OTEC) are reviewed, and a schematic layout of a system is included. The two systems currently under study, the open system and the closed system, are described. The prospect now, it is noted, is that OTEC plants will not be commercially viable on a widespread basis, even in the tropics. This is especially true of the large-scale plants that have been envisioned. A strong possibility is seen, however, that smaller plants, generating about 40 megawatts of electrical power, can survive commercially. The following conditions would favor their success: placement on land rather than at sea; placement in areas (such as islands) where alternative energy supplies are at a premium; and designing the plant to operate in conjunction with either an aquaculture or a desalination plant.

  4. Power conversion apparatus and method

    DOEpatents

    Su, Gui-Jia [Knoxville, TN

    2012-02-07

    A power conversion apparatus includes an interfacing circuit that enables a current source inverter to operate from a voltage energy storage device (voltage source), such as a battery, ultracapacitor or fuel cell. The interfacing circuit, also referred to as a voltage-to-current converter, transforms the voltage source into a current source that feeds a DC current to a current source inverter. The voltage-to-current converter also provides means for controlling and maintaining a constant DC bus current that supplies the current source inverter. The voltage-to-current converter also enables the current source inverter to charge the voltage energy storage device, such as during dynamic braking of a hybrid electric vehicle, without the need of reversing the direction of the DC bus current.

  5. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, A.; Miller, J.

    2010-11-10

    The efficient and cost-effective direct conversion of solar photons into solar electricity and solar fuels is one of the most important scientific and technological challenges of this century. It is estimated that at least 20 terawatts of carbon-free energy (1 and 1/2 times the total amount of all forms of energy consumed today globally), in the form of electricity and liquid and gaseous fuels, will be required by 2050 in order to avoid the most serious consequences of global climate change and to ensure adequate global energy supply that will avoid economic chaos. But in order for solar energy to contribute a major fraction of future carbon-free energy supplies, it must be priced competitively with, or perhaps even be less costly than, energy from fossil fuels and nuclear power as well as other renewable energy resources. The challenge of delivering very low-cost solar fuels and electricity will require groundbreaking advances in both fundamental and applied science. This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer. The direct conversion of solar photons to electricity via photovoltaic (PV) cells is a vital present-day commercial industry, with PV module production growing at about 75%/year over the past 3 years. However, the total installed yearly averaged energy capacity at the end of 2009 was about 7 GW-year (0.2% of global electricity usage). Thus, there

  6. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, C.E.; Eimerl, D.; Velsko, S.P.; Roberts, D.

    1993-11-23

    Temperature-insensitive, phase-matched harmonic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions. 12 figures.

  7. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, Charles E.; Eimerl, David; Velsko, Stephan P.; Roberts, David

    1993-01-01

    Temperature-insensitive, phase-matched harmomic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions.

  8. Solar energy conversion using surface plasmons for broadband energy transport

    NASA Technical Reports Server (NTRS)

    Anderson, L. M.

    1982-01-01

    A new strategy for efficient solar energy conversion based on parallel processing with surface plasmons is introduced. The approach is unique in identifying: (1) a broadband carrier with suitable range for energy transport, and (2) a technique to extract more energy from the more energetic photons, without sequential losses or unique materials for each frequency band. The aim is to overcome the fundamental losses associated with the broad solar spectrum and to achieve a higher level of spectrum splitting than has been possible in semiconductor systems.

  9. Coupled field induced conversion between destructive and constructive quantum interference

    NASA Astrophysics Data System (ADS)

    Jiang, Xiangqian; Sun, Xiudong

    2016-12-01

    We study the control of quantum interference in a four-level atom driven by three coherent fields forming a closed loop. The spontaneous emission spectrum shows two sets of peaks which are dramatically influenced by the fields. Due to destructive quantum interference, a dark line can be observed in the emission spectrum, and the condition of the dark line is given. We found that the conversion between destructive and constructive quantum interference can be achieved through controlling the Rabi frequency of the external fields.

  10. Frequency noise properties of lasers for interferometry in nanometrology.

    PubMed

    Hrabina, Jan; Lazar, Josef; Holá, Miroslava; Cíp, Ondřej

    2013-02-07

    In this contribution we focus on laser frequency noise properties and their influence on the interferometric displacement measurements. A setup for measurement of laser frequency noise is proposed and tested together with simultaneous measurement of fluctuations in displacement in the Michelson interferometer. Several laser sources, including traditional He-Ne and solid-state lasers, and their noise properties are evaluated and compared. The contribution of the laser frequency noise to the displacement measurement is discussed in the context of other sources of uncertainty associated with the interferometric setup, such as, mechanics, resolution of analog-to-digital conversion, frequency bandwidth of the detection chain, and variations of the refractive index of air.

  11. Neural correlates of motor conversion disorder.

    PubMed

    Scott, Rebekah L; Anson, J Gregory

    2009-04-01

    Conversion Disorder affects voluntary motor and sensory function and involves unexplained neurological symptoms without an organic cause. Many researchers have attempted to explain how these symptoms arise but the neural correlates associated with Conversion Disorder remain largely unknown to clinicians and neuroscientists alike. This review focuses on investigations of Conversion Disorder (with motor symptoms) when deficits in voluntary movement occur. No single consistent hypothesis has emerged regarding the underlying cortical mechanisms associated with motor Conversion Disorder. However, findings from electrophysiology, neuroimaging, and behavioral research implicate the involvement of prefrontal networks. With further research using measurement techniques precise in spatial as well as temporal resolution, the conflict associated with two views of the neural correlates of motor Conversion Disorder may be resolved. This will provide a better understanding of the impairment associated with the preparation, generation, and execution of intentional movement in Conversion Disorder.

  12. AUTOMATIC FREQUENCY CONTROL SYSTEM

    DOEpatents

    Hansen, C.F.; Salisbury, J.D.

    1961-01-10

    A control is described for automatically matching the frequency of a resonant cavity to that of a driving oscillator. The driving oscillator is disconnected from the cavity and a secondary oscillator is actuated in which the cavity is the frequency determining element. A low frequency is mixed with the output of the driving oscillator and the resultant lower and upper sidebands are separately derived. The frequencies of the sidebands are compared with the secondary oscillator frequency. deriving a servo control signal to adjust a tuning element in the cavity and matching the cavity frequency to that of the driving oscillator. The driving oscillator may then be connected to the cavity.

  13. The chemistry of energy conversion and storage.

    PubMed

    Su, Dang Sheng

    2014-05-01

    What's in store: The sustainable development of our society requires the conversion and storage of renewable energy, and these should be scaled up to serve the global primary energy consumption. This special issue on "The Chemistry of Energy Conversion and Storage", assembled by guest editor Dangsheng Su, contains papers dealing with these aspects, and highlights important developments in the chemistry of energy conversion and storage during the last two years.

  14. NASA Radioisotope Power Conversion Technology NRA Overview

    NASA Technical Reports Server (NTRS)

    Anderson, David J.

    2005-01-01

    The focus of the National Aeronautics and Space Administration's (NASA) Radioisotope Power Systems (RPS) Development program is aimed at developing nuclear power and technologies that would improve the effectiveness of space science missions. The Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) is an important mechanism through which research and technology activities are supported in the Advanced Power Conversion Research and Technology project of the Advanced Radioisotope Power Systems Development program. The purpose of the RPCT NRA is to advance the development of radioisotope power conversion technologies to provide higher efficiencies and specific powers than existing systems. These advances would enable a factor of two to four decrease in the amount of fuel and a reduction of waste heat required to generate electrical power, and thus could result in more cost effective science missions for NASA. The RPCT NRA selected advanced RPS power conversion technology research and development proposals in the following three areas: innovative RPS power conversion research, RPS power conversion technology development in a nominal 100 W(sub e) scale; and, milliwatt/multi-watt RPS (mWRPS) power conversion research. Ten RPCT NRA contracts were awarded in 2003 in the areas of Brayton, Stirling, thermoelectric (TE), and thermophotovoltaic (TPV) power conversion technologies. This paper will provide an overview of the RPCT NRA, a summary of the power conversion technologies approaches being pursued, and a brief digest of first year accomplishments.

  15. NASA Radioisotope Power Conversion Technology NRA Overview

    NASA Technical Reports Server (NTRS)

    Anderson, David J.

    2005-01-01

    The focus of the National Aeronautics and Space Administration s (NASA) Radioisotope Power Systems (RPS) Development program is aimed at developing nuclear power and technologies that would improve the effectiveness of space science missions. The Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) is an important mechanism through which research and technology activities are supported in the Advanced Power Conversion Research and Technology project of the Advanced Radioisotope Power Systems Development program. The purpose of the RPCT NRA is to advance the development of radioisotope power conversion technologies to provide higher efficiencies and specific powers than existing systems. These advances would enable a factor of 2 to 4 decrease in the amount of fuel and a reduction of waste heat required to generate electrical power, and thus could result in more cost effective science missions for NASA. The RPCT NRA selected advanced RPS power conversion technology research and development proposals in the following three areas: innovative RPS power conversion research, RPS power conversion technology development in a nominal 100We scale; and, milliwatt/multi-watt RPS (mWRPS) power conversion research. Ten RPCT NRA contracts were awarded in 2003 in the areas of Brayton, Stirling, thermoelectric (TE), and thermophotovoltaic (TPV) power conversion technologies. This paper will provide an overview of the RPCT NRA, a summary of the power conversion technologies approaches being pursued, and a brief digest of first year accomplishments.

  16. Solar energy, its conversion and utilization

    NASA Technical Reports Server (NTRS)

    Farber, E. A.

    1972-01-01

    The work being carried out at the University of Florida Solar Energy and Energy Conversion Laboratory in converting solar energy, our only income, into other needed and useful forms of energy is described. A treatment such as this demonstrates, in proper perspective, how solar energy can benefit mankind with its many problems of shortages and pollution. Descriptions were given of the conversion processes, equipment, and performance. The testing of materials, solar water heating, space heating, cooking and baking, solar distillation, refrigeration and air-conditioning, work with the solar furnace, conversion to mechanical power, hot air engines, solar-heated sewage digestion, conversion to electricity, and other devices will be discussed.

  17. Advanced power conversion based on the Aerocapacitor{trademark}

    SciTech Connect

    Josephs, L.C.; Gregory, D.; Roark, D.

    1997-10-01

    The authors report here, for the first time, high frequency testing of a new type of electrochemical double layer capacitor (EDLC), based on carbon aerogels: the Aerocapacitor. Carbon aerogels, are a novel type of carbon foam developed by Lawrence Livermore National Laboratory for military applications. The unique properties of carbon aerogels, high surface area (700 m{sup 2}/g), high density (1g/cc), well controlled pore diameter and high material conductivity (25 S/cm) made it an ideal EDLC electrode material. Using carbon aerogel as the electrode material, the authors have developed Aerocapacitors. These new EDLC`s have a frequency response comparable to that of aluminum electrolytic capacitors and are thus ideally suited to power conversion applications.

  18. Diode-pumped self-frequency-doubled neodymium yttrium aluminum borate (NYAB) laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1992-01-01

    Over 50 mW of the fundamental-mode 531-nm laser output was obtained with approximately 4 percent optical-to-optical conversion efficiency from a self-frequency-doubling NYAB crystal when pumped with two 1-W diode lasers. The prospect of higher conversion efficiency is discussed.

  19. Direct optical to microwave conversion

    NASA Astrophysics Data System (ADS)

    Taylor, Henry F.

    1990-09-01

    Support of high frequency fiber optic links through development of innovative higher efficiency techniques to convert optical energy directly to RF Energy. Control of Phases Arrays by optical means in an area of expanding technology development. Fiber optics and other forms of optical waveguide can provide greater accuracy and true time delay in a phase delay network. Methods of improvement in transfer of optical energy to RF Energy are determined. Development of Direct Optical-to-RF-Direct Amplifiers will result in higher efficiency, low noise, optical receivers for fiber optic links with improved performance. This results in longer fiber optic links without repeaters and improved BER or shorter links.

  20. DDC Descriptor Frequencies.

    ERIC Educational Resources Information Center

    Klingbiel, Paul H.; Jacobs, Charles R.

    This report summarizes the frequency of use of the 7144 descriptors used for indexing technical reports in the Defense Documentation Center (DDC) collection. The descriptors are arranged alphabetically in the first section and by frequency in the second section. The frequency data cover about 427,000 AD documents spanning the interval from March…

  1. 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.

  2. 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.…

  3. Frequency Response Tool

    SciTech Connect

    Etingov, Pavel; Chassin, PNNL David; Zhang, PNNL Yu; PNNL,

    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 lead 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.

  4. Thermophotovoltaic Energy Conversion Development Program

    NASA Technical Reports Server (NTRS)

    Shukla, Kailash; Doyle, Edward; Becker, Frederick

    1998-01-01

    Completely integrated thermophotovoltaic (TPV) power sources in the range of 100 to 500 watts are being developed. The technical approach taken in this project focuses on optimizing the integrated performance of the primary subsystems in order to yield high energy conversion efficiency and cost effectiveness. An important aspect of the approach is the use of a narrow band fibrous emitter radiating to a bandgap matched photovoltaic array to minimize thermal and optical recuperation requirements, as well as the non-recoverable heat losses. For the prototype system, fibrous ytterbia emitters radiating in a narrow band centered at 980 nm are matched with high efficiency silicon photoconverters. The integrated system includes a dielectric stack filter for optical energy recovery and a ceramic recuperator for thermal energy recovery. The prototype TPV system uses a rapid mix distributed fuel delivery system with controlled feeding of the fuel and heated air into a flame at the surface of the emitter. This makes it possible to operate at air preheat temperatures well above the auto-ignition temperature of the fuel thereby substantially increasing the system efficiency. The system has been operated with air preheat temperatures up to 1367 K and has produced a uniform narrow band radiation over the surface of the emitter with this approach. The design of the system is described and test data for the system and some of the key components are presented. The results from a system model, which show the impact of various parameters on system performance, are also discussed.

  5. Clean Fossil Energy Conversion Processes

    NASA Astrophysics Data System (ADS)

    Fan, L.-S.

    2007-03-01

    Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

  6. Conversion of pentoses by yeasts

    SciTech Connect

    Gong, C.S.; Claypool, T.A.; Maun, C.M.; Mccracken, L.D.; Tsao, G.T.; Ueng, P.P.

    1983-01-01

    The utilization and conversion of D-xylose, D-xyulose, L-arabinose, and xylitol by yeast strains have been investigated with the following results: 1) The majority of yeasts tested utilize D-xylose and produce polyols, ethanol, and organic acids. The type and amount of products formed varies with the yeast strains used. The most commonly detected product is xylitol. 2) The majority of yeasts tested utilize D-xylulose aerobically and fermentatively to produce ethanol, xylitol D-arabitol, and organic acids. The type and amount of products varies depending upon the yeast strains used. 3) Xylitol is a poor carbon and energy source for most yeasts tested. Some yeast strains produce small amounts of ethanol from xylitol. 4) Most yeast strains utilize L-arabinose, and L-arabitol is the common product. Small amounts of ethanol are also produced by some yeast strains. 5) Of the four substrates examined, D-xylulose was the preferred substrate, followed by D-xylose, L-arabinose, and xylitol. 6) Mutant yeast strains that exhibit different metabolic product patterns can be induced and isolated from Candida sp. Saccharomyces cerevisiae, and other yeasts. These mutant strains can be used for ethanol production from D-xylose as well as for the study of metabolic regulation of pentose utilization in yeasts.

  7. Interdigitated photovoltaic power conversion device

    DOEpatents

    Ward, James Scott; Wanlass, Mark Woodbury; Gessert, Timothy Arthur

    1999-01-01

    A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device.

  8. Interdigitated photovoltaic power conversion device

    DOEpatents

    Ward, J.S.; Wanlass, M.W.; Gessert, T.A.

    1999-04-27

    A photovoltaic power conversion device has a top surface adapted to receive impinging radiation. The device includes at least two adjacent, serially connected cells. Each cell includes a semi-insulating substrate and a lateral conductivity layer of a first doped electrical conductivity disposed on the substrate. A base layer is disposed on the lateral conductivity layer and has the same electrical charge conductivity thereof. An emitter layer of a second doped electrical conductivity of opposite electrical charge is disposed on the base layer and forms a p-n junction therebetween. A plurality of spaced channels are formed in the emitter and base layers to expose the lateral conductivity layer at the bottoms thereof. A front contact grid is positioned on the top surface of the emitter layer of each cell. A first current collector is positioned along one outside edge of at least one first cell. A back contact grid is positioned in the channels at the top surface of the device for engagement with the lateral conductivity layer. A second current collector is positioned along at least one outside edge of at least one oppositely disposed second cell. Finally, an interdigitation mechanism is provided for serially connecting the front contact grid of one cell to the back contact grid of an adjacent cell at the top surface of the device. 15 figs.

  9. Tropospheric effects of energy conversion

    SciTech Connect

    Derwent, R.G. )

    1992-01-01

    The tropospheric concentrations of a number of trace gases are increasing due to man's activities. For some trace gases, their atmospheric life cycles are not fully understood and it is difficult to be certain about the role of man's activities. Emissions from the energy industries and energy conversion processes represent an important subset of source terms in these life cycles, along with agriculture, deforestation, cement manufacture, biomass burning, process industries and natural biospheric processes. Global Warming Potentials (GWPs) allow the tropospheric effects of a range of climate forcing trace gases to be assessed on a comparable basis. If a short term view of the commitment to global warming is adopted then the contribution from other trace gases may approach and exceed that of carbon dioxide, itself. Over longer time horizons, the long atmospheric lifetime of carbon dioxide shows through as a major influence and the contributions from the other trace gases appear to be much smaller, representing an additional 13-18[percent] contribution on top of that from CO[sub 2] itself.

  10. Catalytic conversion of light alkanes

    SciTech Connect

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  11. Energy Conversion Alternatives Study (ECAS)

    NASA Technical Reports Server (NTRS)

    1977-01-01

    ECAS compared various advanced energy conversion systems that can use coal or coal-derived fuels for baseload electric power generation. It was conducted in two phases. Phase 1 consisted of parametric studies. From these results, 11 concepts were selected for further study in Phase 2. For each of the Phase 2 systems and a common set of ground rules, performance, cost, environmental intrusion, and natural resource requirements were estimated. In addition, the contractors defined the state of the associated technology, identified the advances required, prepared preliminary research and development plans, and assessed other factors that would affect the implementation of each type of powerplant. The systems studied in Phase 2 include steam systems with atmospheric- and pressurized-fluidized-bed boilers; combined cycle gas turbine/steam systems with integrated gasifiers or fired by a semiclean, coal derived fuel; a potassium/steam system with a pressurized-fluidized-bed boiler; a closed-cycle gas turbine/organic system with a high-temperature, atmospheric-fluidized-bed furnace; a direct-coal-fired, open- cycle magnetohydrodynamic/steam system; and a molten-carbonate fuel cell/steam system with an integrated gasifier. The sensitivity of the results to changes in the ground rules and the impact of uncertainties in capital cost estimates were also examined.

  12. A conversation with Joseph Lau.

    PubMed

    Lau, Joseph; Cappelleri, Joseph C; Ingerick, Meghan

    2015-03-01

    Dr. Joseph Lau is a world-leading expert in meta-analysis and systematic reviews. Currently a professor in the Department of Health Services, Policy and Practice and co-director of the Center for Evidence-based Medicine at Brown University, Professor Lau has applied evidence-based methods to a variety of clinical, biomedical and healthcare topics; has developed reliable and efficient methods and tools to conduct systematic reviews and meta-analyses; and has advanced an understanding on the impact of factors that may contribute to differences of results in scientific studies. His past research includes cumulative meta-analysis of randomized controlled trials, comparison of results from large trials and meta-analyses of small trials, effect of baseline risk in the interpretation of clinical trial results, and empirical evaluation of existing methods of combining data. His current focus is on a Web-based repository of systematic review data, reviews of diagnostic tests, nutrition, clinical practice guidelines, and dissemination of evidence-based methods to varied health-care disciplines. This report is a conversation from an adapted version of an interview, more or less chronologically arranged, between Joseph C. Cappelleri as interviewer and Joseph Lau as interviewee, with Meghan Ingerick recording and transcribing the interview.

  13. Keep meaning in conversational coordination

    PubMed Central

    Cuffari, Elena C.

    2014-01-01

    Coordination is a widely employed term across recent quantitative and qualitative approaches to intersubjectivity, particularly approaches that give embodiment and enaction central explanatory roles. With a focus on linguistic and bodily coordination in conversational contexts, I review the operational meaning of coordination in recent empirical research and related theorizing of embodied intersubjectivity. This discussion articulates what must be involved in treating linguistic meaning as dynamic processes of coordination. The coordination approach presents languaging as a set of dynamic self-organizing processes and actions on multiple timescales and across multiple modalities that come about and work in certain domains (those jointly constructed in social, interactive, high-order sense-making). These processes go beyond meaning at the level that is available to first-person experience. I take one crucial consequence of this to be the ubiquitously moral nature of languaging with others. Languaging coordinates experience, among other levels of behavior and event. Ethical effort is called for by the automatic autonomy-influencing forces of languaging as coordination. PMID:25520693

  14. Fundamentals of solar energy conversion

    NASA Astrophysics Data System (ADS)

    Anderson, E. E.

    This textbook strives to strengthen a student's knowledge of the basic sciences as well as to provide a practical background in solar energy conversion. Particular consideration is given to solar geometry, the availability of solar energy, solar concentrators, elements of fluid mechanics and heat transfer in solar systems, flat-plate collectors, and thermal storage of solar energy. The use of solar energy for specific types of loads is then discussed. The application of active solar systems to space and hot-water heating is considered, and a description is given of the empirical f-chart method for thermal-performance analysis. The economics of solar systems is examined along with the application of solar energy to cooling and dehumidification loads as well as the application of solar energy to industrial and other thermal loads. The concept of passive systems is explained, and the evaluation of thermal performance on the basis of the empirical load/collector ratio method is described. Appendixes are presented with such information as solar-position charts, tables of solar radiation and climatic data, and programs for hand-held calculators.

  15. Economic conversion: The US experience

    SciTech Connect

    Williams, R.C.

    1994-12-31

    At the end of the Second World War, our country experienced what economists have called {open_quotes}The Great Conversion{close_quotes} or {open_quotes}The Great Disarmament.{close_quotes} Following that period and until the beginning of the Viet-Nam War was a time marked by economic expansion and boom. Since those years, there have been several periods during which bases were closed and defense spending was slowed. For the communities going through these transitions, again there was economic expansion. A recent survey reports that, within the last 25 years, over 100 communities redeveloped their economic base and experienced, not catastrophy as they expected, but a period of economic growth. Jobs were not lost but nearly doubled. Small businesses and educational institutions multiplied. Building starts accelerated. The survey attributed this economic growth to proper planning, increased awareness of the need for job training and education, diversification of economic activity, and an ownership on the part of the citizens in their collective economic future. The lesson for us should be that realigning our community economic priorities away from such a strong emphasis on military spending and toward a diverse and productive civilian economy brings economic health. We are relearning this lesson in the redevelopment of Lowry Air Force Base and the transition of Rocky Flats Nuclear Plant from a weapons manufacturing mission to one of cleanup.

  16. Cryogenic power conversion: Combining HT superconductors and semiconductors

    NASA Astrophysics Data System (ADS)

    Mueller, Otward

    1992-04-01

    The availability and use of high-temperature superconductors (HTS) will require and enforce completely new electronic systems concepts. One of many possible applications could and probably will be the field of ac/dc, dc/ac as well as RF power conversion at the multi-kilowatt level. Until HTS high frequency switches able to handle hundreds of volts and tens of amperes are invented and produced commercially existing semiconductor devices such as the power MOS field-effect transistor can be used advantageously in order to implement ultra-high efficiency circuits in combination with HTS components such as high Q inductors and capacitors. This marriage could result in a drastic size, weight and cost reduction for various suitable high power applications. The key to high efficiency power conversion are so-called zero-voltage switching circuits known as single transistor Class E and half-bridge Class D amplifiers. This paper analyzes and discusses some relevant design criteria such as conversion efficiency etc. versus temperature down to 77 K.

  17. Degree of Conversational Code-Switching Enhances Verbal Task Switching in Cantonese-English Bilinguals

    ERIC Educational Resources Information Center

    Yim, Odilia; Bialystok, Ellen

    2012-01-01

    The study examined individual differences in code-switching to determine the relationship between code-switching frequency and performance in verbal and non-verbal task switching. Seventy-eight Cantonese-English bilinguals completed a semi-structured conversation to quantify natural code-switching, a verbal fluency task requiring language…

  18. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use an... catalytic activity of the NO2-to-NO converter has not deteriorated. (b) Measurement principles. An NO2-to-NO.... Allow for stabilization, accounting only for transport delays and instrument response. (ii) Use an...

  19. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... verification. 1065.378 Section 1065.378 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications Nox and N2o Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  20. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... verification. 1065.378 Section 1065.378 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications Nox and N2o Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  1. Effect of electron flow on the ordinary-extraordinary mode conversion

    SciTech Connect

    Jia Guozhang; Gao Zhe

    2011-10-15

    Ordinary-extraordinary mode conversion in the electron cyclotron frequency range is revisited in the presence of a flowing electron component. The analytical expressions of optimal parallel refraction index and conversion efficiency are obtained from a one-dimensional cold plasma model. The presence of flowing electrons leads to an outward shift of the conversion layer and therefore increases the optimal value of parallel refraction index. If this effect is not considered, the efficiency of mode conversion degenerates. In typical tokamak plasmas, this degeneration is about a few percentages, which may induce the reflection of several tens of kilowatts of power from the cutoff layer when injecting megawatts of ECRF power into fusion plasma.

  2. In situ conversion of porphyrin microbubbles to nanoparticles for multimodality imaging

    NASA Astrophysics Data System (ADS)

    Huynh, Elizabeth; Leung, Ben Y. C.; Helfield, Brandon L.; Shakiba, Mojdeh; Gandier, Julie-Anne; Jin, Cheng S.; Master, Emma R.; Wilson, Brian C.; Goertz, David E.; Zheng, Gang

    2015-05-01

    Converting nanoparticles or monomeric compounds into larger supramolecular structures by endogenous or external stimuli is increasingly popular because these materials are useful for imaging and treating diseases. However, conversion of microstructures to nanostructures is less common. Here, we show the conversion of microbubbles to nanoparticles using low-frequency ultrasound. The microbubble consists of a bacteriochlorophyll-lipid shell around a perfluoropropane gas. The encapsulated gas provides ultrasound imaging contrast and the porphyrins in the shell confer photoacoustic and fluorescent properties. On exposure to ultrasound, the microbubbles burst and form smaller nanoparticles that possess the same optical properties as the original microbubble. We show that this conversion is possible in tumour-bearing mice and could be validated using photoacoustic imaging. With this conversion, our microbubble can potentially be used to bypass the enhanced permeability and retention effect when delivering drugs to tumours.

  3. Frequency-noise measurements of optical frequency combs by multiple fringe-side discriminator

    PubMed Central

    Coluccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, Gianluca

    2015-01-01

    The frequency noise of an optical frequency comb is routinely measured through the hetherodyne beat of one comb tooth against a stable continuous-wave laser. After frequency-to-voltage conversion, the beatnote is sent to a spectrum analyzer to retrive the power spectral density of the frequency noise. Because narrow-linewidth continuous-wave lasers are available only at certain wavelengths, heterodyning the comb tooth can be challenging. We present a new technique for direct characterization of the frequency noise of an optical frequency comb, requiring no supplementary reference lasers and easily applicable in all spectral regions from the terahertz to the ultraviolet. The technique is based on the combination of a low finesse Fabry-Perot resonator and the so-called “fringe-side locking” method, usually adopted to characterize the spectral purity of single-frequency lasers, here generalized to optical frequency combs. The effectiveness of this technique is demonstrated with an Er-fiber comb source across the wavelength range from 1 to 2 μm. PMID:26548900

  4. 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).

  5. 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.

  6. Frequency selective infrared sensors

    SciTech Connect

    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.

  7. Harmonic Frequency Lowering

    PubMed Central

    Kirchberger, Martin

    2016-01-01

    A novel algorithm for frequency lowering in music was developed and experimentally tested in hearing-impaired listeners. Harmonic frequency lowering (HFL) combines frequency transposition and frequency compression to preserve the harmonic content of music stimuli. Listeners were asked to make judgments regarding detail and sound quality in music stimuli. Stimuli were presented under different signal processing conditions: original, low-pass filtered, HFL, and nonlinear frequency compressed. Results showed that participants reported perceiving the most detail in the HFL condition. In addition, there was no difference in sound quality across conditions. PMID:26834122

  8. A novel approach for using polyphase filter bank in directly digital RF conversion from RF to baseband

    NASA Astrophysics Data System (ADS)

    Zhang, Deying; Jiang, Qin; Ahmed, Mohiuddin

    2012-05-01

    Software defined radio (SDR) hardware platform is in high demand for ultra-wideband digital EW receiver to carry out different mission requirements. Due to the limitations of current Analog-to-Digital conversion (ADC) techniques, the ideal receiver structure of SDR, with digital RF frequency conversion, cannot be achieved. In this article, a new channelization technique called ADC polyphase fast Fourier transformation (ADC PFFT) filter bank channelization is demonstrated. The key concept is to separate the speed at which the two functional units of an ADC - the sample and hold and the quantizer - operate. The sample and hold unit operates at the sampling frequency fs and the quantizer (the speed limiting factor in ADCs) can operate at a much slower rate, fs/M, where M is the decimation factor for digital filter bank. By integrated this ADC PFFT technique in ultra-wideband digital channelized EW receivers, directly digital RF down conversion can be achieved. With the ADC PFFT channelization for RF down conversion and polyphase FFT channelization for IF down conversion, 2-18 GHz frequency coverage can be accomplished in such ultra-wideband digital channelized EW receivers without the requirement of EW receivers being time-shared among outputs from many subbands due to bandwidth limitation in digital IF channelized EW receivers. Because the frequency down conversion from RF to BB are all processed digitally, issues such as image rejection and I/Q imbalance due to analog mixing will be eliminated in the ultrawideband digital channelized EW receivers.

  9. Mode conversion at the higher ion cyclotron harmonics

    NASA Astrophysics Data System (ADS)

    Chiu, S. C.; Chan, V. S.; Harvey, R. W.; Porkolab, M.

    1989-07-01

    It has been demonstrated that mode conversion of fast waves to ion Bernstein waves can be calculated from a reduced second order differential equation for the wave fields rather than the 4th order equations used in earlier studies near the ion-ion hybrid resonance and the second harmonic resonance. Here the underlying justification of the method is discussed. It is shown that the method works for high harmonic resonances and an analytical formula for the tunneling coefficient is derived. The result is a generalization of a previous result obtained by Ngan and Swanson and is applicable when κ⊥ρi is large. Recently, there is interest in using fast waves for current drive at high ion cyclotron harmonics frequencies in tokamaks. Generally, the fast wave will encounter ion cyclotron harmonics within the plasma cross-section. For efficient current drive, the minimization of the mode conversion processes sets restrictions to the choice of frequencies and magnetic fields. This is discussed using the derived formula.

  10. Agricultural Land Conversion: Background and Issues.

    ERIC Educational Resources Information Center

    Furuseth, Owen J.

    1982-01-01

    Analyzes forces contributing to the conversion of agricultural land for other uses, causes for the depletion of the land, major issues surrounding the loss of farmland, and current policies designed to control haphazard land conversion. Concludes that the United States lacks a national farmland protection policy. (KC)

  11. Caveats of an English Conversation Club.

    ERIC Educational Resources Information Center

    Simpson, JoEllen; Ossa, Carlos E.; Rutter, Frank P.

    1999-01-01

    Describes an English conversation club that was initiated at the Universidad del Valle in Cali, Colombia. Suggests ways in which other university communities can better serve their English-speaking populations by creating a similar English conversation club. (Author/VWL)

  12. Improving Teamwork through Awareness of Conversational Styles

    ERIC Educational Resources Information Center

    Rehling, Louise

    2004-01-01

    Conversational styles can sometimes cause conflicts on problem-solving writing teams. In self-defense, students often resort to blaming and shaming around conversational styles, which can just worsen unproductive group behaviors, limiting idea exchanges and deflecting attention from substantive issues and onto what is often labeled "personality…

  13. Conversion Disorder in Australian Pediatric Practice

    ERIC Educational Resources Information Center

    Kozlowska, Kasia; Nunn, Kenneth P.; Rose, Donna; Morris, Anne; Ouvrier, Robert A.; Varghese, John

    2007-01-01

    Objectives: To describe the incidence and clinical features of children presenting to Australian child health specialists with conversion disorder. Method: Active, national surveillance of conversion disorder in children younger than 16 years of age during 2002 and 2003. Results: A total of 194 children were reported on. The average age was 11.8…

  14. An Analysis of Televised Telephone Conversations.

    ERIC Educational Resources Information Center

    Skokut, Nina

    1993-01-01

    The structure of televised conversations were compared with theoretical structures of such conversations, based on data drawn from commercial television soap operas. Results show that portions resemble naturally occurring speech as represented in theoretical frameworks, but others do not; implications for language teachers are noted. (17…

  15. Biocatalytic conversion of lignocellulose to platform chemicals.

    PubMed

    Jäger, Gernot; Büchs, Jochen

    2012-09-01

    Naturally occurring lignocellulose can be used as a renewable resource for the sustainable production of platform chemicals that can in turn be converted to valuable fine chemicals, polymers, and fuels. The biocatalytic conversion of lignocellulose is a very promising approach due to its high selectivity, mild conditions, and low exergy loss. However, such biocatalytic processes are still seldom applied at the industrial scale since the single conversion steps (pretreatment, hydrolysis, and fermentation) may exhibit low conversion rates, low efficiencies, or high costs. The biocatalytic conversion of lignocellulose to platform chemicals is reviewed in this work. Structures and production rates of lignocellulose are described, and platform chemicals that may be produced from lignocellulose are summarized. Biocatalytic conversion of lignocellulose is distinguished from conventional non-selective approaches. All essential conversion steps used in biocatalytic approaches (pretreatment, hydrolysis, and fermentation) are reviewed in detail. Finally, potential interactions between these conversion steps are highlighted and the advantages as well as disadvantages of integrated process configurations are elucidated. In conclusion, a comprehensive understanding of the biocatalytic conversion of lignocellulose is provided in this review.

  16. 43 CFR 3140.4 - Conversion.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Conversion. 3140.4 Section 3140.4 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Conversion of...

  17. 43 CFR 3140.4 - Conversion.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Conversion. 3140.4 Section 3140.4 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Conversion of...

  18. 43 CFR 3140.4 - Conversion.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Conversion. 3140.4 Section 3140.4 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Conversion of...

  19. 43 CFR 3140.4 - Conversion.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Conversion. 3140.4 Section 3140.4 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Conversion of...

  20. A Course in Conversation as Cultural Practice

    ERIC Educational Resources Information Center

    Knutson, Elizabeth M.

    2010-01-01

    This paper describes an upper level foreign language course designed to enable students to "learn about conversation" as both a universal and culture-specific form of talk, and to "learn to converse" at an advanced level and in culturally appropriate ways with speakers of French from France and Francophone countries. Students…

  1. Mathematical Conversations to Transform Algebra Class

    ERIC Educational Resources Information Center

    Szydlik, Jennifer Earles

    2015-01-01

    Classroom culture is established through both conversations and practices. Traditionally in mathematics class, the focus is primarily on the latter; that is, students are shown what "doing mathematics" looks like, and then asked that they try it themselves. This article discusses three mathematical conversations that help bring…

  2. The Role of Conversation in Technology Education

    ERIC Educational Resources Information Center

    Fox-Turnbull, Wendy

    2010-01-01

    This article investigates recent literature in the area of classroom conversation and dialogue with the aim of gaining a better understanding of the role that classroom conversation and dialogue plays in learning. It also investigates literature on the constructivist, collaborative nature of technology education and suggests that to enhance our…

  3. Reflection during Portfolio-Based Conversations

    ERIC Educational Resources Information Center

    Oosterbaan, Anne E.; van der Schaaf, Marieke F.; Baartman, Liesbeth K. J.; Stokking, Karel M.

    2010-01-01

    This study aims to explore the relationship between the occurrence of reflection (and non-reflection) and thinking activities (e.g., orientating, selecting, analysing) during portfolio-based conversations. Analysis of 21 transcripts of portfolio-based conversations revealed that 20% of the segments were made up of reflection (content reflection…

  4. Collective Contexts in Conversation: Grounding by Proxy

    ERIC Educational Resources Information Center

    Eshghi, Arash; Healey, Patrick G. T.

    2016-01-01

    Anecdotal evidence suggests that participants in conversation can sometimes act as a coalition. This implies a level of conversational organization in which groups of individuals form a coherent unit. This paper investigates the implications of this phenomenon for psycholinguistic and semantic models of shared context in dialog. We present a…

  5. Guide to Software Conversion Management. [Final Report.

    ERIC Educational Resources Information Center

    Skall, M., Ed.

    Based mainly on interviews conducted at 14 federal agencies that had completed or were involved in software conversion projects, this publication provides guidelines for the entire process of software conversion. This is defined as the transformation, without functional change, of computer programs or data elements to permit their use on a…

  6. 5 CFR 534.506 - Conversion provisions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... conversion, other than to the minimum rate under 5 U.S.C. 5376, the increase must be approved by the head of... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Conversion provisions. 534.506 Section... OTHER SYSTEMS Pay for Senior-Level and Scientific and Professional Positions § 534.506...

  7. 5 CFR 534.605 - Conversion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Conversion. 534.605 Section 534.605... Administrative Appeals Judge Positions § 534.605 Conversion. On the first day of the first pay period beginning on or after December 11, 2001, agencies must convert the rate of basic pay of an...

  8. 5 CFR 534.605 - Conversion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Conversion. 534.605 Section 534.605... Administrative Appeals Judge Positions § 534.605 Conversion. On the first day of the first pay period beginning on or after December 11, 2001, agencies must convert the rate of basic pay of an...

  9. 5 CFR 534.506 - Conversion provisions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... conversion, other than to the minimum rate under 5 U.S.C. 5376, the increase must be approved by the head of... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Conversion provisions. 534.506 Section... OTHER SYSTEMS Pay for Senior-Level and Scientific and Professional Positions § 534.506...

  10. Effects of Conversational Pressures on Speech Planning

    ERIC Educational Resources Information Center

    Swets, Benjamin; Jacovina, Matthew E.; Gerrig, Richard J.

    2013-01-01

    In ordinary conversation, speakers experience pressures both to produce utterances suited to particular addressees and to do so with minimal delay. To document the impact of these conversational pressures, our experiment asked participants to produce brief utterances to describe visual displays. We complicated utterance planning by including…

  11. Biomass thermal conversion research at SERI

    SciTech Connect

    Milne, T. A.; Desrosiers, R. E.; Reed, T. B.

    1980-09-01

    SERI's involvement in the thermochemical conversion of biomass to fuels and chemicals is reviewed. The scope and activities of the Biomass Thermal Conversion and Exploratory Branch are reviewed. The current status and future plans for three tasks are presented: (1) Pyrolysis Mechanisms; (2) High Pressure O/sub 2/ Gasifier; and (3) Gasification Test Facility.

  12. Genetic Effects on Children's Conversational Language Use

    ERIC Educational Resources Information Center

    DeThorne, Laura S.; Petrill, Stephen A.; Hart, Sara A.; Channell, Ron W.; Campbell, Rebecca J.; Deater-Deckard, Kirby; Thompson, Lee Anne; Vanderbergh, David J.

    2008-01-01

    Purpose: The present study examined the extent of genetic and environmental influences on individual differences in children's conversational language use. Method: Behavioral genetic analyses focused on conversational measures and 2 standardized tests from 380 twins (M = 7.13 years) during the 2nd year of the Western Reserve Reading Project (S. A.…

  13. Provoking Reflective Thinking in Post Observation Conversations

    ERIC Educational Resources Information Center

    Kim, Younhee; Silver, Rita Elaine

    2016-01-01

    We present a micro-analysis of post observation conversations between classroom teachers and mentors. Using the approach of conversation analysis, we show how the sequential organization of an episode (i.e., who initiates the interaction, question format used by mentors) could potentially serve to provoke or hinder teacher reflection. Our analysis…

  14. How to Engage in Effective Conversation

    ERIC Educational Resources Information Center

    Hutchins, Robin L.

    2009-01-01

    Conversation skills are essential for success in social, school, and business settings. They are foundational to deep relationships and lifelong friendships. Job applicants leave a more favorable impression with good conversation skills. Employees with these skills are more likely to climb the company ladder than those who struggle with…

  15. Retrospective Conversion Manual: University Library Recon Project.

    ERIC Educational Resources Information Center

    Ramage, Pat

    This manual provides a brief description of the procedures employed by the University of South Alabama in converting their library records from print to computerized cataloging. A description of the procedure is followed by detailed instructions and examples. Rules for NOTIS-LCCN Conversion Records, OCLC--Telex Transfer, and Conversion of…

  16. Retrospective Conversion: Investing in the Future.

    ERIC Educational Resources Information Center

    Boss, Richard

    1984-01-01

    Report on developments in the retrospective conversion of manual library files to machine-readable form discusses planning and decision making; accommodating full records; conforming to standards; creating bibliographic records; sources of retrospective conversion support (bibliographic utilities, stand-alone systems); use of microcomputers;…

  17. 1982 annual report: Biomass Thermochemical Conversion Program

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1983-01-01

    This report provides a brief overview of the Thermochemical Conversion Program's activities and major accomplishments during fiscal year 1982. The objective of the Biomass Thermochemical Conversion Program is to generate scientific data and fundamental biomass converison process information that, in the long term, could lead to establishment of cost effective processes for conversion of biomass resources into clean fuels and petrochemical substitutes. The goal of the program is to improve the data base for biomass conversion by investigating the fundamental aspects of conversion technologies and exploring those parameters which are critical to these conversion processes. To achieve this objective and goal, the Thermochemical Conversion Program is sponsoring high-risk, long-term research with high payoff potential which industry is not currently sponsoring, nor is likely to support. Thermochemical conversion processes employ elevated temperatures to convert biomass materials into energy. Process examples include: combustion to produce heat, steam, electricity, direct mechanical power; gasification to produce fuel gas or synthesis gases for the production of methanol and hydrocarbon fuels; direct liquefaction to produce heavy oils or distillates; and pyrolysis to produce a mixture of oils, fuel gases, and char. A bibliography of publications for 1982 is included.

  18. Enhancing Classroom Conversation for All Students

    ERIC Educational Resources Information Center

    Goldsmith, William

    2013-01-01

    The author, a 5th-grade teacher, offers strategies intended to assist and encourage ELL students to participate in academic conversations. They include insisting that children take part in conversations despite their apprehension and teaching them the language they need to communicate their ideas. One strategy is Think, Pair, Share--a simple…

  19. Study of a condition for the mode conversion from purely perpendicular electrostatic waves to electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Kalaee, Mohammad Javad; Katoh, Yuto

    2016-07-01

    One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma waves (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.

  20. Radio frequency spectrum management

    NASA Astrophysics Data System (ADS)

    Sujdak, E. J., Jr.

    1980-03-01

    This thesis is a study of radio frequency spectrum management as practiced by agencies and departments of the Federal Government. After a brief introduction to the international agency involved in radio frequency spectrum management, the author concentrates on Federal agencies engaged in frequency management. These agencies include the National Telecommunications and Information Administration (NTIA), the Interdepartment Radio Advisory Committee (IRAC), and the Department of Defense (DoD). Based on an analysis of Department of Defense frequency assignment procedures, recommendations are given concerning decentralizing military frequency assignment by delegating broader authority to unified commanders. This proposal includes a recommendation to colocate the individual Service frequency management offices at the Washington level. This would result in reduced travel costs, lower manpower requirements, and a common tri-Service frequency management data base.

  1. Conversion Disorder— Mind versus Body: A Review

    PubMed Central

    Jabeen, Shagufta; Pate, Rebecca J.; Shahid, Marwah; Chinala, Sandhya; Nathani, Milankumar; Shah, Rida

    2015-01-01

    In this article, the authors accentuate the signs and symptoms of conversion disorder and the significance of clinical judgment and expertise in order to reach the right diagnosis. The authors review the literature and provide information on the etiology, prevalence, diagnostic criteria, and the treatment methods currently employed in the management of conversion disorder. Of note, the advancements of neuropsychology and brain imaging have led to emergence of a relatively sophisticated picture of the neuroscientific psychopathology of complex mental illnesses, including conversion disorder. The available evidence suggests new methods with which to test hypotheses about the neural circuits underlying conversion symptoms. In context of this, the authors also explore the neurobiological understanding of conversion disorder. PMID:26155375

  2. [Management of patients with conversion disorder].

    PubMed

    Vermeulen, Marinus; Hoekstra, Jan; Kuipers-van Kooten, Mariëtte J; van der Linden, Els A M

    2014-01-01

    The symptoms of conversion disorder are not due to conscious simulation. There should be no doubt that the symptoms of conversion disorder are genuine, even if scans do not reveal any abnormalities. The management of patients with conversion disorder starts with an explanation of the diagnosis. The essence of this explanation is that patients first hear about what the diagnosis actually means and only after this about what they do not have. When explaining the diagnosis it is a good idea to use metaphors. The treatment of patients with conversion disorder is carried out together with a physical therapist. The collaboration of healthcare professionals who are involved in the treatment of a patient with conversion disorder should preferably be coordinated by the patient's general practitioner.

  3. Conversion Disorder- Mind versus Body: A Review.

    PubMed

    Ali, Shahid; Jabeen, Shagufta; Pate, Rebecca J; Shahid, Marwah; Chinala, Sandhya; Nathani, Milankumar; Shah, Rida

    2015-01-01

    In this article, the authors accentuate the signs and symptoms of conversion disorder and the significance of clinical judgment and expertise in order to reach the right diagnosis. The authors review the literature and provide information on the etiology, prevalence, diagnostic criteria, and the treatment methods currently employed in the management of conversion disorder. Of note, the advancements of neuropsychology and brain imaging have led to emergence of a relatively sophisticated picture of the neuroscientific psychopathology of complex mental illnesses, including conversion disorder. The available evidence suggests new methods with which to test hypotheses about the neural circuits underlying conversion symptoms. In context of this, the authors also explore the neurobiological understanding of conversion disorder.

  4. A Conversation with Adam Heller.

    PubMed

    Heller, Adam; Cairns, Elton J

    2015-01-01

    Adam Heller, Ernest Cockrell Sr. Chair in Engineering Emeritus of the John J. McKetta Department of Chemical Engineering at The University of Texas at Austin, recalls his childhood in the Holocaust and his contributions to science and technology that earned him the US National Medal of Technology and Innovation in a conversation with Elton J. Cairns, Professor of Chemical and Biomolecular Engineering at the University of California, Berkeley. Dr. Heller, born in 1933, describes the enslavement of his father by Hungarians in 1942; the confiscation of his family's home, business, and all its belongings in 1944; and his incarceration in a brick factory with 18,000 Jews who were shipped by the Hungarians to be gassed by Germans in Auschwitz. Dr. Heller and his immediate family survived the Holocaust and arrived in Israel in 1945. He studied under Ernst David Bergmann at the Hebrew University, and then worked at Bell Laboratories and GTE Laboratories, where he headed Bell Lab's Electronic Materials Research Department. At GTE Laboratories, he built in 1966 the first neodymium liquid lasers and in 1973 with Jim Auborn conceived and engineered the lithium thionyl chloride battery, one of the first to be manufactured lithium batteries, which is still in use. After joining the faculty of engineering of The University of Texas at Austin, he cofounded with his son Ephraim Heller TheraSense, now a major part of Abbott Diabetes Care, which produced a microcoulometer that made the monitoring of glucose painless by accurately measuring the blood glucose concentration in 300 nL of blood. He also describes the electrical wiring of enzymes, the basis for Abbott's state-of-the-art continuous glucose monitoring system. He discusses his perspective of reducing the risk of catastrophic global warming in a wealth-accumulating, more-energy-consuming world and provides advice for students entering careers in science or engineering.

  5. Adaptability of solar energy conversion systems on ships

    NASA Astrophysics Data System (ADS)

    Visa, I.; Cotorcea, A.; Neagoe, M.; Moldovan, M.

    2016-08-01

    International trade of goods largely uses maritime/transoceanic ships driven by engines using fossil fuels. This two centuries tradition is technologically mature but significantly adds to the CO2 emissions; therefore, recent trends focus on on-board implementation of systems converting the solar energy into power (photovoltaic systems) or heat (solar-thermal systems). These systems are carbon-emissions free but are still under research and plenty of effort is devoted to fast reach maturity and feasibility. Unlike the systems implemented in a specific continental location, the design of solar energy conversion systems installed on shipboard has to face the problem generated by the system base motion along with the ship travelling on routes at different latitudes: the navigation direction and sense and roll-pitch combined motion with reduced amplitude, but with relatively high frequency. These raise highly interesting challenges in the design and development of mechanical systems that support the maximal output in terms of electricity or heat. The paper addresses the modelling of the relative position of a solar energy conversion surface installed on a ship according to the current position of the sun; the model is based on the navigation trajectory/route, ship motion generated by waves and the relative sun-earth motion. The model describes the incidence angle of the sunray on the conversion surface through five characteristic angles: three used to define the ship orientation and two for the solar angles; based on, their influence on the efficiency in solar energy collection is analyzed by numerical simulations and appropriate recommendations are formulated for increasing the solar energy conversion systems adaptability on ships.

  6. Observation of frequency doubling in tantalum doped silica fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    Second harmonic conversion efficients of 3 x 0,0001 in tantalum-doped silica fibers prepared by the seeding technique are reported. A series of experiments were conducted to characterize the frequency doubling in this fiber and to compare the results to the behavior observed in germanosilicate and rare earth-doped aluminosilicate fibers.

  7. Technology for satellite power conversion

    NASA Technical Reports Server (NTRS)

    Gouker, M. A.; Campbell, D. P.; Gallagher, J. J.

    1987-01-01

    Components were examined that will be needed for high frequency rectenna devices. The majority of the effort was spent on measuring the directivity and efficiency of the half-wave dipole antenna. It is felt that the antenna and diode should be roughly optimized before they are combined into a rectenna structure. An integrated low pass filter had to be added to the antenna structure in order to facilitate the field pattern measurements. A calculation was also made of the power density of the Earth's radiant energy as seen by satellites in Earth orbit. Finally, the feasibility of using a Metal-Oxide-Metal (MOM) diode for rectification of the received power was assessed.

  8. Technology for satellite power conversion

    NASA Technical Reports Server (NTRS)

    Gouker, M. A.; Campbell, D. P.; Gallagher, J. J.

    1986-01-01

    The work performed in this reporting period has concentrated on the metal-oxide-metal (MOM) diode. The fabrication procedure begins with the deposition of gold probing pads to provide a non-oxidizing contact to test the dc characteristics to the diode accurately. A thin patch capped with an insulating SiO2 layer, is deposited next to form the first half of the diode. The other half of the diode, typically Ni, is deposited completing the conduction path from the oxidized edge of the Ni patch to the opposite gold probing pad. It is important in this step that the last metallization take place without exposing the newly oxidized surface to the atmosphere. Successful production of diodes has been achieved. Work on millimeter wave frequency rectennas incorporating known semiconductor diode technology has been initiated.

  9. Phase-dependent interference between frequency doubled comb lines in a χ(2) phase-matched aluminum nitride microring.

    PubMed

    Jung, Hojoong; Guo, Xiang; Zhu, Na; Papp, Scott B; Diddams, Scott A; Tang, Hong X

    2016-08-15

    Nonlinear optical conversion with frequency combs is important for self-referencing and for generating shorter wavelength combs. Here we demonstrate efficient frequency comb doubling through the combination of second-harmonic generation (SHG) and sum-frequency generation (SFG) of an input comb with a high Q, phase-matched χ(2) microring resonator. Phase coherence of the SHG and SFG nonlinear conversion processes is confirmed by sinusoidal phase-dependent interference between frequency doubled comb lines.

  10. A deep-UV optical frequency comb at 205 nm.

    PubMed

    Peters, E; Diddams, S A; Fendel, P; Reinhardt, S; Hänsch, T W; Udem, Th

    2009-05-25

    By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser at 820 nm we generate a frequency comb at 205 nm with nearly bandwidth-limited pulses. The nonlinear frequency conversion is accomplished by two successive frequency doubling stages that take place in resonant cavities that are matched to the pulse repetition rate of 82 MHz. This allows for an overall efficiency of 4.5 % and produces an output power of up to 70 mW for a few minutes and 25 mW with continuous operation for hours. Such a deep UV frequency comb may be employed for direct frequency comb spectroscopy in cases where it is less efficient to convert to these short wavelengths with continuous wave lasers.

  11. 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.

  12. Modeling of frequency doubling and tripling with converter refractive index spatial non-uniformities due to gravitational sag

    SciTech Connect

    De Yoreo, J J; Auerbach, J M; Barker, C E; Couture, S A; Eimerl, D; Hackel, L A; Hibbard, R L; Liou, L W; Norton, M; Wegner, P J

    1998-08-03

    Accurate predictions of the performance of frequency conversion requires knowledge of the spatial variation of departures from the phase-matching condition in the converter crystals. This variation is caused by processes such as crystal growth and crystal surface finishing. Gravitational sag and mounting configurations also lead to deformation and stresses which cause spatially varying departures from the phase-matching condition. We have modeled the effect of gravitational forces on conversion efficiency performance of horizontal converter crystals and have shown for the NIF mounting configurations that gravity has very little effect on conversion efficiency. Keywords: Frequency conversion, ICF, Nonlinear optics, KDP crystals

  13. The Growing Regulation of Conversion Therapy

    PubMed Central

    Drescher, Jack; Schwartz, Alan; Casoy, Flávio; McIntosh, Christopher A.; Hurley, Brian; Ashley, Kenneth; Barber, Mary; Goldenberg, David; Herbert, Sarah E.; Lothwell, Lorraine E.; Mattson, Marlin R.; McAfee, Scot G.; Pula, Jack; Rosario, Vernon; Tompkins, D. Andrew

    2016-01-01

    Conversion therapies are any treatments, including individual talk therapy, behavioral (e.g. aversive stimuli), group therapy or milieu (e.g. “retreats or inpatient treatments” relying on all of the above methods) treatments, which attempt to change an individual’s sexual orientation from homosexual to heterosexual. However these practices have been repudiated by major mental health organizations because of increasing evidence that they are ineffective and may cause harm to patients and their families who fail to change. At present, California, New Jersey, Oregon, Illinois, Washington, DC, and the Canadian Province of Ontario have passed legislation banning conversion therapy for minors and an increasing number of US States are considering similar bans. In April 2015, the Obama administration also called for a ban on conversion therapies for minors. The growing trend toward banning conversion therapies creates challenges for licensing boards and ethics committees, most of which are unfamiliar with the issues raised by complaints against conversion therapists. This paper reviews the history of conversion therapy practices as well as clinical, ethical and research issues they raise. With this information, state licensing boards, ethics committees and other regulatory bodies will be better able to adjudicate complaints from members of the public who have been exposed to conversion therapies. PMID:27754500

  14. Ownership Conversions and Nursing Home Performance

    PubMed Central

    Grabowski, David C; Stevenson, David G

    2008-01-01

    Objective To examine the effects of ownership conversions on nursing home performance. Data Source Online Survey, Certification, and Reporting system data from 1993 to 2004, and the Minimum Data Set (MDS) facility reports from 1998 to 2004. Study Design Regression specification incorporating facility fixed effects, with terms to identify trends in the pre- and postconversion periods. Principal Findings The annual rate of nursing home conversions almost tripled between 1994 and 2004. Our regression results indicate converting facilities are generally different throughout the pre/postconversion years, suggesting little causal effect of ownership conversions on nursing home performance. Before and after conversion, nursing homes converting from nonprofit to for-profit status generally exhibit deterioration in their performance, while nursing homes converting from for-profit to nonprofit status generally exhibit improvement. Conclusions Policy makers have expressed concern regarding the implications of ownership conversions for nursing home performance. Our results imply that regulators and policy makers should not only monitor the outcomes of nursing home conversions, but also the targets of these conversions. PMID:18355255

  15. Propagation and linear mode conversion of magnetosonic and electromagnetic ion cyclotron waves in the radiation belts

    NASA Astrophysics Data System (ADS)

    Horne, Richard B.; Miyoshi, Yoshizumi

    2016-10-01

    Magnetosonic waves and electromagnetic ion cyclotron (EMIC) waves are important for electron acceleration and loss from the radiation belts. It is generally understood that these waves are generated by unstable ion distributions that form during geomagnetically disturbed times. Here we show that magnetosonic waves could be a source of EMIC waves as a result of propagation and a process of linear mode conversion. The converse is also possible. We present ray tracing to show how magnetosonic (EMIC) waves launched with large (small) wave normal angles can reach a location where the wave normal angle is zero and the wave frequency equals the so-called crossover frequency whereupon energy can be converted from one mode to another without attenuation. While EMIC waves could be a source of magnetosonic waves below the crossover frequency, magnetosonic waves could be a source of hydrogen band waves but not helium band waves.

  16. Quantum non-Gaussianity of frequency up-converted single photons.

    PubMed

    Baune, Christoph; Schönbeck, Axel; Samblowski, Aiko; Fiurášek, Jaromír; Schnabel, Roman

    2014-09-22

    Nonclassical states of light are an important resource in today's quantum communication and metrology protocols. Quantum up-conversion of nonclassical states is a promising approach to overcome frequency differences between disparate subsystems within a quantum information network. Here, we present the generation of heralded narrowband single photons at 1550 nm via cavity enhanced spontaneous parametric down-conversion (SPDC) and their subsequent up-conversion to 532 nm. Quantum non-Gaussianity (QNG), which is an important feature for applications in quantum information science, was experimentally certified for the first time in frequency up-converted states.

  17. Cooled Ion Frequency Standard

    DTIC Science & Technology

    1988-09-27

    on Frequency Standards and Metrology, Ancona , Italy (Springer Verlag, 1988) to be published. 8. "High Accuracy Spectroscopy of Stored Ions," D.J...Wineland, W.M. Itano, J.S. Bergquist, J.J. Bollinger, F. Diedrich and S.L. Gilbert, Proc. 4th Symp. on Frequency Standards and Metrology, Ancona , Italy...Proc. 4th Symp. on Frequency Standards and Metrology, Ancona , Italy (Springer Verlag, 1988) to be published. 10. "Quantative Study of Laser Cooling in

  18. Processing of Microalgae: Acoustic Cavitation and Hydrothermal Conversion

    NASA Astrophysics Data System (ADS)

    Greenly, Justin Michael

    The production of energy dense fuels from renewable algal biomass feedstocks -- if sustainably developed at a sufficiently large scale -- may reduce the consumption of petroleum from fossil fuels and provide many environmental benefits. Achieving economic feasibility has several technical engineering challenges that arise from dilute concentration of growing algae in aqueous media, small cell sizes, and durable cell walls. For microalgae to be a sustainable source of biofuels and co-products, efficient fractionation and conversion of the cellular contents is necessary. Research was carried out to address two processing options for efficient microalgae biofuel production: 1. Ultrasonic cavitation for cell disruption and 2. Hydrothermal conversion of a model algal triglyceride. 1. Ultrasonic cell disruption, which relies on cavitating bubbles in the suspension to produce damaging shock waves, was investigated experimentally over a range of concentrations and species types. A few seconds of high intensity sonication at fixed frequency yielded significant cell disruption, even for the more durable cells. At longer exposure times, effectiveness was seen to decline and was attributed, using acoustic measurements, to ultrasonic power attenuation in the ensuing cloud of cavitating bubbles. Processing at higher cell concentrations slowed cell disintegration marginally, but increased the effectiveness of dissipating ultrasonic energy. A theoretical study effectively predicted optimal conditions for a variety of parameters that were inaccessible in this experimental investigation. In that study, single bubble collapse was modeled to identify operating conditions that would increase cavitation, and thus cell disruption. Simulations were conducted by varying frequency and pressure amplitude of the ultrasound wave, and initial bubble size. The simulation results indicated that low frequency, high sound wave amplitudes, and small initial bubble size generate the highest shock

  19. Energy conversion & storage program. 1994 annual report

    SciTech Connect

    Cairns, E.J.

    1995-04-01

    The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  20. Energy Conversion & Storage Program, 1993 annual report

    SciTech Connect

    Cairns, E.J.

    1994-06-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  1. Technique for measuring gas conversion factors

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Sprinkle, D. R. (Inventor)

    1985-01-01

    A method for determining hydrocarbon conversion factors for a flowmeter. A mixture of air, O2 and C sub x H sub y is burned and the partial paressure of O2 in the resulting gas is forced to equal the partial pressure of O2 in air. The flowrate of O2 flowing into the mixture is measured by flowmeter and the flowrate of C sub x H sub y flowing into the mixture is measured by the flowmeter conversion factor is to be determined. These measured values are used to calculate the conversion factor.

  2. Thermionic Energy Conversion (TEC) topping thermoelectrics

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1981-01-01

    Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

  3. Thermionic energy conversion technology - Present and future

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Morris, J. F.

    1977-01-01

    Aerospace and terrestrial applications of thermionic direct energy conversion and advances in direct energy conversion (DEC) technology are surveyed. Electrode materials, the cesium plasma drop (the difference between the barrier index and the collector work function), DEC voltage/current characteristics, conversion efficiency, and operating temperatures are discussed. Attention is centered on nuclear reactor system thermionic DEC devices, for in-core or out-of-core operation. Thermionic fuel elements, the radiation shield, power conditions, and a waste heat rejection system are considered among the thermionic DEC system components. Terrestrial applications include topping power systems in fossil fuel and solar power generation.

  4. Multi-Frequency Synthesis

    NASA Astrophysics Data System (ADS)

    Sault, R. J.; Conway, J. E.

    Multi-frequency synthesis is the practice of using visibility data measured over a range of frequencies when forming a continuum image. Because observing frequency is easier to vary than antenna location, it is an effective way of filling the (u,v) plane for an observation. Here we consider the artifacts in MFS images caused by source spectral variation. For frequency ranges of about 30%, for observations where only modest dynamic range is required, the artifacts of MFS can be completely ignored. For higher dynamic range observations, some calibration techniques and deconvolution algorithms are described which minimize the artifacts.

  5. Frequency Response Analysis Tool

    SciTech Connect

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

    2014-12-01

    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.

  6. Probability and Relative Frequency

    NASA Astrophysics Data System (ADS)

    Drieschner, Michael

    2016-01-01

    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. 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

  8. 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.

  9. Nonlinear resonance converse magnetoelectric effect modulated by voltage for the symmetrical magnetoelectric laminates under magnetic and thermal loadings

    NASA Astrophysics Data System (ADS)

    Zhou, Hao-Miao; Liu, Hui; Zhou, Yun; Hu, Wen-Wen

    2016-12-01

    Based on the tri-layer symmetrical magnetoelectric laminates, a equivalent circuit for the nonlinear resonance converse magnetoelectric coupling effect is established. Because the nonlinear thermo-magneto-mechanical constitutive equations of magnetostrictive material were introduced, a converse magnetoelectric coefficient model was derived from the equivalent circuit, which can describe the influence of bias electric field, bias magnetic field and ambient temperature on the resonance converse magnetoelectric coupling effect. Especially, the model can well predict the modulation effect of bias electric field/voltage on the magnetism of magnetoelectric composite or the converse magnetoelectric coefficient, which is absolutely vital in applications. Both of the converse magnetoelectric coefficient and the resonance frequency predicted by the model have good agreements with the existing experimental results in qualitatively and quantitatively, and the validity of the model is confirmed. On this basis, according to the model, the nonlinear trends of the resonance converse magnetoelectric effect under different bias voltages, bias magnetic fields and ambient temperatures are predicted. From the results, it can be found that the bias voltage can effectively modulate the curve of the resonance converse magnetoelectric coefficient versus bias magnetic field, and then change the corresponding optimal bias magnetic field of the maximum converse magnetoelectric coefficient; with the increasing volume ratio of piezoelectric layers, the modulation effect of bias voltage becomes more obvious; under different bias magnetic fields, the modulation effect of bias voltage on the converse magnetoelectric effect has nonvolatility in a wide temperature region.

  10. Frequency Scale Correction of Fourier Spectrometers in the Visible

    NASA Astrophysics Data System (ADS)

    Serdyukov, V. I.

    2016-05-01

    It has been found that when visible molecular absorption spectra are recorded with the IFS-125M Fourier spectrometer, a shift in the frequency scale is observed which increases nonlinearly toward higher frequencies. It is proposed that the frequency scale be corrected using absorption lines of iodine vapor and water, beginning with calibration of the wavelength scale where the correction function is linear to a good approximation, followed by conversion of the calibration to a wave number scale. The error in determining the wave numbers of the absorption lines does not exceed ±0.003 cm-1.

  11. Gallium nitride based power switches for next generation of power conversion

    SciTech Connect

    Chowdhury, S

    2015-03-17

    Power conversion impacts all areas of electricity consumption, including motion control, lighting, air conditioning, and information technology. Si, the workhorse of the industry, has served well so far but reached its material limits. To keep up with the advancement of technologies enabling new conveniences, power conversion techniques need to go through significant transformation that calls for the next generation semiconductor for power switching. SiC and GaN, which have the potential to push the envelope beyond Si providing solutions for the entire range of power conversion at higher efficiencies and reduced form factors. GaN HEMTs have an added advantage over SiC MOSFETs owing to the high-mobility electron channel formed at the AlGaN/GaN interface, which has been the basis of radio frequency amplifiers. GaN has enabled systems that can run with lesser cooling at frequencies at least ten times higher than current Si-based systems, significantly reducing the form factor both electrically (passive components) and mechanically (heat sinks). The high current and voltage required for high power conversion application make the chip area in a lateral topology uneconomical and difficult to manufacture. Vertical GaN devices on bulk GaN substrates complete the portfolio of power switches required to address the power conversion market.

  12. Passenger and Cell Phone Conversations in Simulated Driving

    ERIC Educational Resources Information Center

    Drews, Frank A.; Pasupathi, Monisha; Strayer, David L.

    2008-01-01

    This study examines how conversing with passengers in a vehicle differs from conversing on a cell phone while driving. We compared how well drivers were able to deal with the demands of driving when conversing on a cell phone, conversing with a passenger, and when driving without any distraction. In the conversation conditions, participants were…

  13. Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role of Laser Linewidth

    DTIC Science & Technology

    2007-11-02

    fiber optic sensors ; atomic frequency standards, applied laser spectroscopy, laser chemistry, atmospheric propagation and beam control, LIDAR/LADAR...SMC-TR-99-11 AEROSPACE REPORT NO. TR-98(8555)-14 Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role of Laser ...1999 3. REPORT TYPE AND DATES COVERED 4. TITLE AND SUBTITLE Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role

  14. Linear mode conversion of Langmuir and ordinary waves in unmagnetized and magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Keller, S.; Kim, E.; Johnson, J.; Cairns, I. H.; Labelle, J. W.

    2012-12-01

    Linear mode conversion (LMC) between Langmuir waves and EM radiation that occurs in inhomogeneous density profiles at frequencies close to the local electron plasma frequency ωpe is relevant to various ionospheric, solar, and heliospheric radio emissions. In this study, we investigate LMC in warm unmagnetized plasmas using a full wave model and wave simulation code including a density gradient. We calculate the power (ɛs) and energy (ɛ) conversion efficiencies for various wave frequencies (ω), incidence angles (θ), density scale lengths, and β = vth2/c2, where vth is the electron thermal speed. We also investigate the effects of various different electron density profiles on LMC, e.g. various E and F region ionospheric density profiles. For unmagnetized plasmas, we show that (a) both ɛs and ɛ are almost a constant as a function of ω for constant ωpe. However, for ω/ ωpe → 1, the angular mode conversion window (Δθ) is clearly reduced and the maximum conversion efficiency (ɛmax and ɛsmax ) increases; (b) When β increases from 0.01 to 0.2, ɛmax linearly increases from 5 to 20% and Δθ of ɛ also becomes wider, while ɛsmax and Δθ ( ɛs= ɛsmax) are not changed and Δθ for ɛs slightly increases.

  15. Transcriptional effects on double-strand break-induced gene conversion tracts.

    PubMed

    Weng, Y S; Xing, D; Clikeman, J A; Nickoloff, J A

    2000-10-16

    Transcription stimulates spontaneous homologous recombination, but prior studies have not investigated the effects of transcription on double-strand break (DSB)-induced recombination in yeast. We examined products of five ura3 direct repeat substrates in yeast using alleles that were transcribed at low or high levels. In each strain, recombination was stimulated by DSBs created in vivo at an HO site in one copy of ura3. Increasing transcription levels in donor or recipient alleles did not further stimulate DSB-induced recombination, nor did it alter the relative frequencies of conversion and deletion (pop-out) events. This result is consistent with the idea that transcription enhances spontaneous recombination by increasing initiation. Gene conversion tracts were measured using silent restriction fragment length polymorphisms (RFLPs) at approximately 100bp intervals. Transcription did not alter average tract lengths, but increased transcription in donor alleles increased both the frequency of promoter-proximal (5') unidirectional tracts and conversion of 5' markers. Increased transcription in recipient alleles increased the frequency of bidirectional tracts. We demonstrate that these effects are due to transcription per se, and not just transcription factor binding. These results suggest that transcription influences aspects of gene conversion after initiation, such as strand invasion and/or mismatch repair (MMR).

  16. Enhancement of optics-to-THz conversion efficiency by metallic slot waveguides.

    PubMed

    Ruan, Zhichao; Veronis, Georgios; Vodopyanov, Konstantin L; Fejer, Marty M; Fan, Shanhui

    2009-08-03

    A metallic slot waveguide, with a dielectric strip embedded within, is investigated for the purpose of enhancing the optics-to-THz conversion efficiency using the difference-frequency generation (DFG) process. To describe the frequency conversion process in such lossy waveguides, a fully-vectorial coupled-mode theory is developed. Using the coupled-mode theory, we outline the basic theoretical requirements for efficient frequency conversion, which include the needs to achieve large coupling coefficients, phase matching, and low propagation loss for both the optical and THz waves. Following these requirements, a metallic waveguide is designed by considering the trade-off between modal confinement and propagation loss. Our numerical calculation shows that the conversion efficiency in these waveguide structures can be more than one order of magnitude larger than what has been achieved using dielectric waveguides. Based on the distinct impact of the slot width on the optical and THz modal dispersion, we propose a two-step method to realize the phase matching for general pump wavelengths.

  17. Terrestrial solar thermionic energy conversion systems concept

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Swerdling, M.

    1975-01-01

    Results obtained from studies of a (1) solar concentrator, (2) solar energy receiver - thermionic converter system, and (3) solar thermionic topping system are described. Peripheral subsystems, which are required for any solar energy conversion system, are also discussed.

  18. Conversion of asphaltene-containing charge stocks

    SciTech Connect

    Conner, A.J.; Hutchings, L.E.

    1982-11-09

    A process is claimed for the conversion of an asphaltene-containing, hydrocarbonaceous black oil in a catalytic slurry reaction zone wherein an admixture of converted hydrocarbonaceous oil and unconverted asphaltenes is recycled to the reaction zone.

  19. Persuasive Conversational Agent with Persuasion Tactics

    NASA Astrophysics Data System (ADS)

    Narita, Tatsuya; Kitamura, Yasuhiko

    Persuasive conversational agents persuade people to change their attitudes or behaviors through conversation, and are expected to be applied as virtual sales clerks in e-shopping sites. As an approach to create such an agent, we have developed a learning agent with the Wizard of Oz method in which a person called Wizard talks to the user pretending to be the agent. The agent observes the conversations between the Wizard and the user, and learns how to persuade people. In this method, the Wizard has to reply to most of the user's inputs at the beginning, but the burden gradually falls because the agent learns how to reply as the conversation model grows.

  20. Condenser design for AMTEC power conversion

    NASA Technical Reports Server (NTRS)

    Crowley, Christopher J.

    1991-01-01

    The condenser and the electrodes are the two elements of an alkali metal thermal-to-electric conversion (AMTEC) cell which most greatly affect the energy conversion performance. A condenser is described which accomplishes two critical functions in an AMTEC cell: management of the fluid under microgravity conditions and optimization of conversion efficiency. The first function is achieved via the use of a controlled surface shape, along with drainage grooves and arteries to collect the fluid. Capillary forces manage the fluid in microgravity and dominate hydrostatic effects on the ground so the device is ground-testable. The second function is achieved via a smooth film of highly reflective liquid sodium on the condensing surface, resulting in minimization of parasitic heat losses due to radiation heat transfer. Power conversion efficiencies of 25 percent to 30 percent are estimated with this condenser using present technology for the electrodes.