Science.gov

Sample records for intermediate frequency system

  1. Complex magnetic field exposure system for in vitro experiments at intermediate frequencies.

    PubMed

    Lodato, Rossella; Merla, Caterina; Pinto, Rosanna; Mancini, Sergio; Lopresto, Vanni; Lovisolo, Giorgio A

    2013-04-01

    In occupational environments, an increasing number of electromagnetic sources emitting complex magnetic field waveforms in the range of intermediate frequencies is present, requiring an accurate exposure risk assessment with both in vitro and in vivo experiments. In this article, an in vitro exposure system able to generate complex magnetic flux density B-fields, reproducing signals from actual intermediate frequency sources such as magnetic resonance imaging (MRI) scanners, for instance, is developed and validated. The system consists of a magnetic field generation system and an exposure apparatus realized with a couple of square coils. A wide homogeneity (99.9%) volume of 210 × 210 × 110 mm(3) was obtained within the coils, with the possibility of simultaneous exposure of a large number of standard Petri dishes. The system is able to process any numerical input sequence through a filtering technique aimed at compensating the coils' impedance effect. The B-field, measured in proximity to a 1.5 T MRI bore during a typical examination, was excellently reproduced (cross-correlation index of 0.99). Thus, it confirms the ability of the proposed setup to accurately simulate complex waveforms in the intermediate frequency band. Suitable field levels were also attained. Moreover, a dosimetry index based on the weighted-peak method was evaluated considering the induced E-field on a Petri dish exposed to the reproduced complex B-field. The weighted-peak index was equal to 0.028 for the induced E-field, indicating an exposure level compliant with the basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Bioelectromagnetics 34:211-219, 2013. © 2012 Wiley Periodicals, Inc. PMID:23060274

  2. Simulation and analysis of an intermediate frequency (IF) distribution system with applications for Space Station

    NASA Technical Reports Server (NTRS)

    Costello, Thomas A.; Brandt, C. Maite

    1989-01-01

    Simulation and analysis results are described for a wideband fiber optic intermediate frequency distribution channel for a frequency division multiple access (FDMA) system where antenna equipment is remotely located from the signal processing equipment. The fiber optic distribution channel accommodates multiple signals received from a single antenna with differing power levels. Performance parameters addressed are intermodulation degradations, laser noise, and adjacent channel interference, as they impact the overall system design. Simulation results showed that the laser diode modulation level can be allowed to reach 100 percent without considerable degradation. The laser noise must be controlled as to provide a noise floor of less than -90 dBW/Hz. The fiber optic link increases the degradation due to power imbalance yet diminishes the effects of the transmit amplifier nonlinearity. Overall, optimal operation conditions can be found to yield a degradation level of about .1 dB caused by the fiber optic link.

  3. Development of multichannel intermediate frequency system for electron cyclotron emission radiometer on KSTAR Tokamak

    SciTech Connect

    Kogi, Yuichiro; Sakoda, Takuya; Mase, Atsushi; Ito, Naoki; Yokota, Yuya; Yamaguchi, Soichiro; Nagayama, Yoshio; Kawahata, Kazuo; Jeong, Seung H.; Kwon, Myeun

    2008-10-15

    Plasma experiments on KSTAR are scheduled to start up this year (2008). We have developed an electron cyclotron emission (ECE) radiometer to measure the radial electron temperature profiles in KSTAR experiments. The radiometer system consists, briefly, of two downconversion stages, amplifiers, bandpass filter banks, and video detectors. These components are made commercially or developed in house. The system detects ECE power in the frequency range from 110 to 196 GHz, the detected signal being resolved by means of 48 frequency windows. Before installation of this system on KSTAR, we installed a part of this system on large helical device (LHD) to study the system under similar plasma conditions. In this experiment, the signal amplitude, considered to be proportional to the electron temperature, is measured. The time-dependent traces of the electron temperature measured by this radiometer are in good agreement with those provided by the LHD Michelson spectrometer. The system noise level which limits the minimum measurable temperature (converted to the electron temperature) is about 30 eV.

  4. Development of multichannel intermediate frequency system for electron cyclotron emission radiometer on KSTAR Tokamak.

    PubMed

    Kogi, Yuichiro; Sakoda, Takuya; Mase, Atsushi; Ito, Naoki; Yokota, Yuya; Yamaguchi, Soichiro; Nagayama, Yoshio; Jeong, Seung H; Kwon, Myeun; Kawahata, Kazuo

    2008-10-01

    Plasma experiments on KSTAR are scheduled to start up this year (2008). We have developed an electron cyclotron emission (ECE) radiometer to measure the radial electron temperature profiles in KSTAR experiments. The radiometer system consists, briefly, of two downconversion stages, amplifiers, bandpass filter banks, and video detectors. These components are made commercially or developed in house. The system detects ECE power in the frequency range from 110 to 196 GHz, the detected signal being resolved by means of 48 frequency windows. Before installation of this system on KSTAR, we installed a part of this system on large helical device (LHD) to study the system under similar plasma conditions. In this experiment, the signal amplitude, considered to be proportional to the electron temperature, is measured. The time-dependent traces of the electron temperature measured by this radiometer are in good agreement with those provided by the LHD Michelson spectrometer. The system noise level which limits the minimum measurable temperature (converted to the electron temperature) is about 30 eV. PMID:19044599

  5. Intermediate frequency band digitized high dynamic range radiometer system for plasma diagnostics and real-time Tokamak control

    SciTech Connect

    Bongers, W. A.; Beveren, V. van; Westerhof, E.; Goede, A. P. H.; Krijger, B.; Berg, M. A. van den; Graswinckel, M. F.; Schueller, F. C.; Thoen, D. J.; Nuij, P. J. W. M.; Baar, M. R. de; Donne, A. J. H.; Hennen, B. A.; Kantor, M.

    2011-06-15

    An intermediate frequency (IF) band digitizing radiometer system in the 100-200 GHz frequency range has been developed for Tokamak diagnostics and control, and other fields of research which require a high flexibility in frequency resolution combined with a large bandwidth and the retrieval of the full wave information of the mm-wave signals under investigation. The system is based on directly digitizing the IF band after down conversion. The enabling technology consists of a fast multi-giga sample analog to digital converter that has recently become available. Field programmable gate arrays (FPGA) are implemented to accomplish versatile real-time data analysis. A prototype system has been developed and tested and its performance has been compared with conventional electron cyclotron emission (ECE) spectrometer systems. On the TEXTOR Tokamak a proof of principle shows that ECE, together with high power injected and scattered radiation, becomes amenable to measurement by this device. In particular, its capability to measure the phase of coherent signals in the spectrum offers important advantages in diagnostics and control. One case developed in detail employs the FPGA in real-time fast Fourier transform (FFT) and additional signal processing. The major benefit of such a FFT-based system is the real-time trade-off that can be made between frequency and time resolution. For ECE diagnostics this corresponds to a flexible spatial resolution in the plasma, with potential application in smart sensing of plasma instabilities such as the neoclassical tearing mode (NTM) and sawtooth instabilities. The flexible resolution would allow for the measurement of the full mode content of plasma instabilities contained within the system bandwidth.

  6. Development and evaluation of intermediate frequency magnetic field exposure system for studies of in vitro biological effects.

    PubMed

    Fujita, Atsushi; Hirota, Izuo; Kawahara, Yoshinobu; Omori, Hideki

    2007-10-01

    We have developed an intermediate frequency (IF) magnetic field exposure system for in vitro studies. Since there are no previous studies on exposure to heating-frequency magnetic fields generated from an induction heating (IH) cook top, there is a strong need for such an exposure system and for biological studies of IF magnetic fields. This system mainly consists of a magnetic-field-generating coil housed inside an incubator, inside which cultured cells can be exposed to magnetic field. Two systems were prepared to allow the experiment to be conducted in a double-blind manner. The level of the generated magnetic field was set to 532 microT rms in the exposure space, 23 kHz, 80 times the value in the International Commission on Non-ionizing Radiation Protection (ICNIRP) guidelines, with a spatial field uniformity better than 3.8%. The waveforms were nearly sinusoidal. It was also confirmed that the parasitic electric field was 157 V/m rms and the induced electric field was 1.9 V/m rms. The temperature was maintained at 36.5 +/- 0.5 degrees C for 2 h. Furthermore, leaked magnetic flux density was 0.7 microT rms or lower at extremely low frequency (ELF) and IF in the stopped system when the other system was being operated, and the environmental magnetic flux density was 0.1 microT rms or lower at the center of the coils. As a result, it was confirmed that this system could be successfully used to evaluate the biological effects of exposure to IF magnetic fields. PMID:17570495

  7. Intermediate water recovery system

    NASA Technical Reports Server (NTRS)

    Deckman, G.; Anderson, A. R. (Editor)

    1973-01-01

    A water recovery system for collecting, storing, and processing urine, wash water, and humidity condensates from a crew of three aboard a spacecraft is described. The results of a 30-day test performed on a breadboard system are presented. The intermediate water recovery system produced clear, sterile, water with a 96.4 percent recovery rate from the processed urine. Recommendations for improving the system are included.

  8. Intermediate Toda systems

    NASA Astrophysics Data System (ADS)

    Damianou, Pantelis A.; Sabourin, Hervé; Vanhaecke, Pol

    2015-05-01

    We construct a large family of Hamiltonian systems which interpolate between the classical Kostant-Toda lattice and the full Kostant-Toda lattice and we discuss their integrability. There is one such system for every nilpotent ideal I in a Borel subalgebra b+ of an arbitrary simple Lie algebra g. The classical Kostant-Toda lattice corresponds to the case of I = [n+, n+], where n+ is the unipotent ideal of b+, while the full Kostant-Toda lattice corresponds to I = {0}. We mainly focus on the case I = [[n+, n+], n+]. In this case, using the theory of root systems of simple Lie algebras, we compute the rank of the underlying Poisson manifolds and construct a set of (rational) functions in involution, large enough to ensure Liouville integrability. These functions are restrictions of well-chosen integrals of the full Kostant-Toda lattice, except for the case of the Lie algebras of type C and D where a different function (Casimir) is needed. The latter fact, and other ones listed in the paper, point at the Liouville integrability of all the systems we construct, but also at the nontriviality of obtaining the result in full generality.

  9. Conductivities of epidermis, dermis, and subcutaneous tissue at intermediate frequencies.

    PubMed

    Wake, K; Sasaki, K; Watanabe, S

    2016-06-21

    Novel data for the conductivities of the tissues composing the skin, which are the epidermis, dermis and subcutaneous tissue, were obtained at intermediate frequencies by in vitro measurement. The conductivity of the epidermis was determined from those of the dermis and bulk skin. The conductivities of the dermis and subcutaneous tissue were almost constant from 10 kHz to 1 MHz. On the other hand, a frequency dependence was observed for the epidermis; the conductivity decreases with decreasing frequency. It was found that the conductivity of bulk skin is not determined by that of the dermis but by that of the epidermis. The presented data are expected to contribute to the assessment of safety and to the research and development of medical applications. PMID:27224275

  10. Conductivities of epidermis, dermis, and subcutaneous tissue at intermediate frequencies

    NASA Astrophysics Data System (ADS)

    Wake, K.; Sasaki, K.; Watanabe, S.

    2016-06-01

    Novel data for the conductivities of the tissues composing the skin, which are the epidermis, dermis and subcutaneous tissue, were obtained at intermediate frequencies by in vitro measurement. The conductivity of the epidermis was determined from those of the dermis and bulk skin. The conductivities of the dermis and subcutaneous tissue were almost constant from 10 kHz to 1 MHz. On the other hand, a frequency dependence was observed for the epidermis; the conductivity decreases with decreasing frequency. It was found that the conductivity of bulk skin is not determined by that of the dermis but by that of the epidermis. The presented data are expected to contribute to the assessment of safety and to the research and development of medical applications.

  11. Interruption Phenomenon in Intermediate-Frequency Vacuum Arc

    NASA Astrophysics Data System (ADS)

    Jiang, Yuan; Wu, Jianwen

    2016-03-01

    In the condition of the 3 mm gap, experiments for 360 Hz intermediate-frequency vacuum arc are carried out in interrupters with the diameters being 41 mm and with the contact materials being CuCr50 and Cu-W-WC alloy respectively. The results indicate that the contacts material is closely related to the breaking capacity of the vacuum interrupters and characteristics of an intermediate-frequency vacuum arc. For contacts with the same diameter, the breaking capacity of CuCr50 is better than that of Cu-W-WC. When the current fails to be interrupted, the arcs overflow the gap and present irregular performances in the first half wave. Consequently a voltage spike appears. More macroscopic metal droplets can be seen in the arc column between CuCr50 contacts because of the lower melting point. It is observed that the droplet emission is much more severe during arc reignition than that in the first half wave. It is much more conspicuous that the high frequency arc voltage noises appear in Cu-W-WC contacts when the vacuum arcs reignite, for higher temperature and stronger electronic emission ability of Cu-W-WC contacts. supported by National Natural Science Foundation of China (No. 51377007), Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20131102130006), and Fundamental Research Funds for the Central Universities of China

  12. Digital intermediate frequency QAM modulator using parallel processing

    DOEpatents

    Pao, Hsueh-Yuan; Tran, Binh-Nien

    2008-05-27

    The digital Intermediate Frequency (IF) modulator applies to various modulation types and offers a simple and low cost method to implement a high-speed digital IF modulator using field programmable gate arrays (FPGAs). The architecture eliminates multipliers and sequential processing by storing the pre-computed modulated cosine and sine carriers in ROM look-up-tables (LUTs). The high-speed input data stream is parallel processed using the corresponding LUTs, which reduces the main processing speed, allowing the use of low cost FPGAs.

  13. Hybrid radio-intermediate-frequency oscillator with photonic-delay-matched frequency conversion pair.

    PubMed

    Dai, Yitang; Wang, Ruixin; Yin, Feifei; Dai, Jian; Zhou, Yue; Li, Jianqiang; Xu, Kun

    2015-06-15

    A low-phase-noise, single-loop radio-frequency (RF) oscillator is proposed and experimentally demonstrated where part of the oscillation is in intermediate-frequency (IF) domain by a pair of frequency conversions. Single-mode operation is achieved by IF filtering. The key design is the matched photonic delay between the two conversions, by which the large phase noise of the common external RF local oscillation (LO) shows no impact on the RF carrier passing through the conversion pair and the low-phase-noise oscillation is guaranteed. The phase-noise performance of the delay-matched conversion pair plus IF filtering is theoretically and experimentally studied. With the proposed scheme, we achieve 120 dBc/Hz phase noise at 10-kHz offset from 10-GHz carrier frequency through a 1-μs loop cavity. PMID:26076289

  14. Multi-frequency communication system and method

    DOEpatents

    Carrender, Curtis Lee; Gilbert, Ronald W.

    2004-06-01

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

  15. Frequency conversion system

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  16. Resonant oscillations of intermediate frequency in a stratified atmosphere.

    NASA Technical Reports Server (NTRS)

    Thompson, O. E.

    1973-01-01

    A class of solutions to a model of forced oscillations in a rotating stratified atmospheric layer is derived and analyzed. The basic model is found to reduce to a boundary value problem with a second-order linear partial differential equation of the hyperbolic type for this range of forcing frequencies. The forced solutions are shown to exhibit resonances with the normal modes of oscillation of the layer. The characteristics of the resonant modes are analyzed in terms of mean tropospheric values of temperature, temperature lapse, wind speed, horizontal and vertical wind shears, latitude, and the frequency and horizontal wavelength of the forcing mechanism. These solutions are compared with solutions to the model for a different (subinertial) range of forcing frequencies. This comparison leads to an elliptic boundary value problem. The solutions in that case do not exhibit the same type of resonance and generally decay away from the region of forcing.

  17. 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.

  18. FREQUENCY STABILIZING SYSTEM

    DOEpatents

    Kerns, Q.A.; Anderson, O.A.

    1960-05-01

    An electronic control circuit is described in which a first signal frequency is held in synchronization with a second varying reference signal. The circuit receives the first and second signals as inputs and produces an output signal having an amplitude dependent upon rate of phase change between the two signals and a polarity dependent on direction of the phase change. The output may thus serve as a correction signal for maintaining the desired synchronization. The response of the system is not dependent on relative phase angle between the two compared signals. By having practically no capacitance in the circuit, there is minimum delay between occurrence of a phase shift and a response in the output signal and therefore very fast synchronization is effected.

  19. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A.; Eide, S.A.

    1993-04-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  20. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A. ); Eide, S.A. )

    1993-01-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  1. Frequency conversion system

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  2. Elimination of Intermediate-Frequency Combustion Instability in the Fastrac Engine Thrust Chamber

    NASA Technical Reports Server (NTRS)

    Rocker, Marvin; Nesman, Tomas E.; Turner, Jim E. (Technical Monitor)

    2001-01-01

    A series of tests were conducted to measure the combustion performance of the Fastrac engine thrust chamber. The thrust chamber exhibited benign, yet marginally unstable combustion. The marginally unstable combustion was characterized by chamber pressure oscillations with large amplitudes and a frequency that was too low to be identified as acoustic or high-frequency combustion instability and too high to be identified as chug or low-frequency combustion instability. The source of the buzz or intermediate-frequency combustion instability was traced to the fuel venturi whose violently noisy cavitation caused resonance in the feedline downstream. Combustion was stabilized by increasing the throat diameter of the fuel venturi such that the cavitation would occur more quietly.

  3. Characterization of surface dielectric barrier discharge influenced by intermediate frequency for ozone production

    NASA Astrophysics Data System (ADS)

    Abdelaziz, Ayman A.; Ishijima, Tatsuo; Seto, Takafumi; Osawa, Naoki; Wedaa, Hassan; Otani, Yoshio

    2016-06-01

    The aim of this study is to investigate the effect of the intermediate frequency (1–10 kHz) of the sinusoidal driving voltage on the characteristics of a developed surface dielectric barrier discharge (SDBD)-based reactor having spikes on its discharge electrode. Moreover, its influence on the production of ozone and nitrogen oxide byproducts is evaluated. The results show that SDBD is operated in the filamentary mode at all the frequencies. Nevertheless, the pulses of the discharge current at high frequencies are much denser and have higher amplitudes than those at low frequencies. The analysis of the power consumed in the reactor shows that a small portion of the input power is dissipated in the dielectric material of SDBD source, whereas the major part of the power is consumed in the plasma discharge. The results of the ozone production show that higher frequencies have a slightly adverse effect on the ozone production at relatively high energy density values, where the ozone concentration is slightly decreased when the frequency is increased at the same energy density. The temperature of the discharge channels and gas is not a crucial factor for the decomposition of ozone in this reactor, while the results of the measurements of nitrogen oxides characteristics indicate that the formation of NO and NO2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect.

  4. The application of the intermediate disturbance hypothesis to physical systems: a case study on floodplain soils

    NASA Astrophysics Data System (ADS)

    Rayburg, Scott; Neave, Melissa; Thompson-Laing, Justin

    2010-05-01

    Disturbances, defined as discrete events that disrupt physical and/or biological systems, are a component of every natural system. Disturbance ecology has been dominated, for the last 30 years or so, by the intermediate disturbance hypothesis that states that biological diversity will be maximised where disturbance occurs at an intermediate level. A wide range of disturbances and organisms have been examined with respect to the intermediate disturbance hypothesis and in many cases (especially with respect to sessile organisms) the theory has proven valid. In rivers, lakes, wetlands and floodplains, the predominant agent of disturbance is flooding. In flood disturbed environments, the intermediate disturbance hypothesis has been shown to apply to terrestrial and aquatic vegetation, but conflicting results have been observed when dealing with mobile organisms like macroinvertebrates, fish or amphibians. The argument for the validity of the intermediate disturbance hypothesis (irrespective of disturbance type) stems from the notion that an intermediate frequency of disturbance promotes diversity by: 1) preventing the competitive exclusion by the dominant species that can arise in infrequently disturbed sites; and 2) facilitating greater diversity than that observed in highly-disturbed sites where only species tolerant of the disturbance can thrive. A singular omission in this logic, and indeed in research into the intermediate disturbance hypothesis more generally, has been the lack of focus on its application or relation to physical systems. This study addresses this lack by investigating whether an intermediate level of flood disturbance leads to a greater diversity of soil character (assessed using a wide range of physical and geochemical soil properties). Four flood frequency (or disturbance frequency) categories are included in this study spanning the range from frequent through to infrequent flood disturbance. These are: a high-inundation-frequency flood zone

  5. Automatic oscillator frequency control system

    NASA Technical Reports Server (NTRS)

    Smith, S. F. (Inventor)

    1985-01-01

    A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.

  6. Swept Frequency Laser Metrology System

    NASA Technical Reports Server (NTRS)

    Zhao, Feng (Inventor)

    2010-01-01

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

  7. Mobile high frequency vibrator system

    SciTech Connect

    Fair, D.W.; Buller, P.L.

    1985-01-08

    A carrier mounted seismic vibrator system that is primarily adapted for generation of high force, high frequency seismic energy into an earth medium. The apparatus includes first and second vibrators as supported by first and second lift systems disposed in tandem juxtaposition generally centrally in said vehicle, and the lift systems are designed to maintain equal hold-down force on the vibrator coupling baseplates without exceeding the weight of the carrier vehicle. The juxtaposed vibrators are then energized in synchronized relationship to propagate increased amounts of higher frequency seismic energy into an earth medium.

  8. Veritas Observations of Relativistic Outflows in - and Intermediate-Frequency BL Lac Objects

    NASA Astrophysics Data System (ADS)

    Prokoph, Heike

    2014-03-01

    The majority of blazars detected at very high energies (VHE; E > 100 GeV) are high-frequency-peaked BL Lac objects (HBLs). Low- and intermediate-frequency-peaked BL Lacs (LBLs/IBLs with synchrotron-peak frequencies in the infrared and optical regime) are generally more powerful, more luminous, and have a richer jet environment than HBLs. However, only a handful of these IBL and LBLs have been detected by ground-based gamma-ray telescopes, typically during high-flux states. The VERITAS array has been monitoring five known VHE LBLs/IBLs since 2009: 3C 66A, W Comae, PKS 1424+240, S5 0716+714 and BL Lacertae, with typical exposures of 5-10 hours per year. The results of these long-term observations are presented, including a bright, subhour-scale VHE flare of BL Lacertae in June 2011, the first low-state detections of 3C 66A and W Comae, and the detection and characterization of the IBL B2 1215+30.

  9. Plasticity of Intermediate Mechanics Students' Coordinate System Choice

    ERIC Educational Resources Information Center

    Sayre, Eleanor C.; Wittman, Michael C.

    2008-01-01

    We investigate the interplay between mathematics and physics resources in intermediate mechanics students. In the mechanics course, the selection and application of coordinate systems is a consistent thread. At the University of Maine, students often start the course with a strong preference to use Cartesian coordinates, in accordance with their…

  10. Initial detailed designs for intermediate photovoltaic systems: Branch bank

    NASA Astrophysics Data System (ADS)

    Obrien, G.; Herz, J.

    1981-12-01

    The first of four detailed PV system designs for intermediate applications with a peak electrical load of 20 to 500 kW is presented. The initial design for a 6 kW direct roof mount, fixed tilt, flat plate array is analyzed for performance and economics. A drawing set, specifications, and installation details are included for procurement and construction bids.

  11. 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.

  12. Definition and realization of the celestial intermediate reference system

    NASA Astrophysics Data System (ADS)

    Capitaine, N.

    2008-07-01

    The transformation between the International Terrestrial Reference System (ITRS) and the Geocentric Celestial Reference system (GCRS) is an essential part of the models to be used when dealing with Earth's rotation or when computing directions of celestial objects in various systems. The 2000 and 2006 IAU resolutions on reference systems have modified the way the Earth orientation is expressed and adopted high accuracy models for expressing the relevant quantities for the transformation from terrestrial to celestial systems. First, the IAU 2000 Resolutions have refined the definition of the astronomical reference systems and transformations between them and adopted the IAU 2000 precession-nutation. Then, the IAU 2006 Resolutions have adopted a new precession model that is consistent with dynamical theories and have addressed definition, terminology or orientation issues relative to reference systems and time scales that needed to be specified after the adoption of the IAU 2000 resolutions. These in particular provide a refined definition of the pole (the Celestial intermediate pole, CIP) and the origin (the Celestial intermediate origin, CIO) on the CIP equator as well as a rigorous definition of sidereal rotation of the Earth. These also allow an accurate realization of the celestial intermediate system linked to the CIP and the CIO that replaces the classical celestial system based on the true equator and equinox of date. This talk explains the changes resulting from the joint IAU 2000/2006 resolutions and reviews the consequences on the concepts, nomenclature, models and conventions in fundamental astronomy that are suitable for modern and future realizations of reference systems. Realization of the celestial intermediate reference system ensuring a micro-arc-second accuracy is detailed.

  13. Kinetic theory of turbulence for parallel propagation revisited: Low-to-intermediate frequency regime

    SciTech Connect

    Yoon, Peter H.

    2015-09-15

    A previous paper [P. H. Yoon, “Kinetic theory of turbulence for parallel propagation revisited: Formal results,” Phys. Plasmas 22, 082309 (2015)] revisited the second-order nonlinear kinetic theory for turbulence propagating in directions parallel/anti-parallel to the ambient magnetic field, in which the original work according to Yoon and Fang [Phys. Plasmas 15, 122312 (2008)] was refined, following the paper by Gaelzer et al. [Phys. Plasmas 22, 032310 (2015)]. The main finding involved the dimensional correction pertaining to discrete-particle effects in Yoon and Fang's theory. However, the final result was presented in terms of formal linear and nonlinear susceptibility response functions. In the present paper, the formal equations are explicitly written down for the case of low-to-intermediate frequency regime by making use of approximate forms for the response functions. The resulting equations are sufficiently concrete so that they can readily be solved by numerical means or analyzed by theoretical means. The derived set of equations describe nonlinear interactions of quasi-parallel modes whose frequency range covers the Alfvén wave range to ion-cyclotron mode, but is sufficiently lower than the electron cyclotron mode. The application of the present formalism may range from the nonlinear evolution of whistler anisotropy instability in the high-beta regime, and the nonlinear interaction of electrons with whistler-range turbulence.

  14. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  15. Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Alves, M. I. R.; Aniano, G.; Armitage-Caplan, C.; Arnaud, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Magalhães, A. M.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Noviello, F.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Rachen, J. P.; Reach, W. T.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Salerno, E.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wandelt, B. D.; Zacchei, A.; Zonca, A.

    2015-04-01

    Planck has mapped the intensity and polarization of the sky at microwave frequencies with unprecedented sensitivity. We use these data to characterize the frequency dependence of dust emission. We make use of the Planck 353 GHz I, Q, and U Stokes maps as dust templates, and cross-correlate them with the Planck and WMAP data at 12 frequencies from 23 to 353 GHz, over circular patches with 10° radius. The cross-correlation analysis is performed for both intensity and polarization data in a consistent manner. The results are corrected for the chance correlation between the templates and the anisotropies of the cosmic microwave background. We use a mask that focuses our analysis on the diffuse interstellar medium at intermediate Galactic latitudes. We determine the spectral indices of dust emission in intensity and polarization between 100 and 353 GHz, for each sky patch. Both indices are found to be remarkably constant over the sky. The mean values, 1.59 ± 0.02 for polarization and 1.51 ± 0.01 for intensity, for a mean dust temperature of 19.6 K, are close, but significantly different (3.6σ). We determine the mean spectral energy distribution (SED) of the microwave emission, correlated with the 353 GHz dust templates, by averaging the results of the correlation over all sky patches. We find that the mean SED increases for decreasing frequencies at ν< 60 GHz for both intensity and polarization. The rise of the polarization SED towards low frequencies may be accounted for by a synchrotron component correlated with dust, with no need for any polarization of the anomalous microwave emission. We use a spectral model to separate the synchrotron and dust polarization and to characterize the spectral dependence of the dust polarization fraction. The polarization fraction (p) of the dust emission decreases by (21 ± 6)% from 353 to 70 GHz. We discuss this result within the context of existing dust models. The decrease in p could indicate differences in polarization

  16. Variable frequency microwave furnace system

    DOEpatents

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

    1994-06-14

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

  17. Variable frequency microwave furnace system

    DOEpatents

    Bible, Don W.; Lauf, Robert J.

    1994-01-01

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

  18. Mode and Intermediate Waters in Earth System Models

    SciTech Connect

    Gnanadesikan, Anand; Sarmiento, Jorge L.

    2015-12-22

    This report describes work done as part of a joint Princeton-Johns Hopkins project to look at the impact of mode and intermediate waters in Earth System Models. The Johns Hopkins portion of this work focussed on the role of lateral mixing in ventilating such waters, with important implications for hypoxia, the uptake of anthropogenic carbon, the dynamics of El Nino and carbon pumps. The Johns Hopkins group also collaborated with the Princeton Group to help develop a watermass diagnostics framework.

  19. Intermediate phases in some rare earth-ruthenium systems

    NASA Technical Reports Server (NTRS)

    Sharifrazi, P.; Raman, A.; Mohanty, R. C.

    1984-01-01

    The phase equilibria and crystal structures of intermediate phases were investigated in eight representative RE-Ru systems using powder X-ray diffraction and metallographic techniques. The Fe3C, Mn5C2 and Er5Ru3 structures occur in all but the Ce-Ru systems. Phases analogous to Er5Ru3 possess an unknown crystal structure similar to Er5Rh3(I). MgCu2 and MgZn2 type Laves phases are encountered in the light rare earth and heavy rare earth systems, respectively, and RERu2 phases, where RE = Nd and Sm, possess both the Laves phase structures. An intermediate phase, NdRu, with an unknown structure, occurs only in the Nd-Ru system. A bcc structure with 40 atoms per unit cell is encountered in the phases Er3Ru2 and Y3Ru2. The behavior of cerium in Ce-Ru alloys is unique in that four unidentified structures, not encountered in other RE-Ru systems, have been encountered. Also a phase designated as Ce3Ru is found with the Th7Fe3 type structure.

  20. System Analysis on Absorption Chiller Utilizing Intermediate Wasted Heat

    NASA Astrophysics Data System (ADS)

    Yamada, Miki; Suzuki, Hiroshi; Usui, Hiromoto

    A system analysis has been performed for the multi-effect absorption chiller (MEAC) applied as a bottoming system of 30kW class hybrid system including micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system. In this paper, an intermediate wasted heat utilization (IWHU) system is suggested for lifting up the energy efficiency of the whole system and coefficient of performance (COP) of MEAC. From the results, the suggested IWHU system was found to show the very high energy efficiency compared with a terminal wasted heat utilization (TWHU) system that uses only the heat exhausted from the terminal of MGT/SOFC system. When TWHU system is applied for MEAC, the utilized heat from the MGT/SOFC system is found to remain low because the temperature difference between the high temperature generator and the wasted heat becomes small. Then, the energy efficiency does not become high in spite of high COP of MEAC. On the other hand, the IWHU system could increase the utilized heat for MEAC as performs effectively. The exergy efficiency of IWHU system is also revealed to be higher than that of a direct gas burning system of MEAC, because the wasted heat is effectively utilized in the IWHU system.

  1. Alternatives generation and analysis for phase I intermediate waste feed staging system design requirements

    SciTech Connect

    Britton, M.D.

    1996-10-02

    This document provides; a decision analysis summary; problem statement; constraints, requirements, and assumptions; decision criteria; intermediate waste feed staging system options and alternatives generation and screening; intermediate waste feed staging system design concepts; intermediate waste feed staging system alternative evaluation and analysis; and open issues and actions.

  2. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1990-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of the frequency during the pulse.

  3. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1989-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of th frequency during the pulse.

  4. Transponder System for High-Frequency Ranging

    NASA Technical Reports Server (NTRS)

    Lichtenberg, C. L.; Shores, P. W.; Kobayashi, H. S.

    1986-01-01

    Transponder system uses phase difference between transmitted and reflected high-frequency radio waves to measure distance to target. To suppress spurious measurements of reflections from objects near target at transmitted frequency and its harmonics, transponder at target generates return signal at half transmitted frequency. System useful in such applications as surveying, docking of ships, and short-range navigation.

  5. Intermediate frequency atmospheric disturbances: A dynamical bridge connecting western U.S. extreme precipitation with East Asian cold surges

    NASA Astrophysics Data System (ADS)

    Jiang, Tianyu; Evans, Katherine J.; Deng, Yi; Dong, Xiquan

    2014-04-01

    In this study, an atmospheric river (AR) detection algorithm is developed to investigate the downstream modulation of the eastern North Pacific ARs by another weather extreme, known as the East Asian cold surge (EACS), in both reanalysis data and high-resolution global model simulations. It is shown that following the peak of an EACS, atmospheric disturbances of intermediate frequency (IF; 10-30 day period) are excited downstream. This leads to the formation of a persistent cyclonic circulation anomaly over the eastern North Pacific that dramatically enhances the AR occurrence probability and the surface precipitation over the western U.S. between 30°N and 50°N. A diagnosis of the local geopotential height tendency further confirms the essential role of IF disturbances in establishing the observed persistent anomaly. This downstream modulation effect is then examined in the two simulations of the National Center for Atmospheric Research Community Climate System Model version 4 with different horizontal resolutions (T85 and T341) for the same period (1979-2005). The connection between EACS and AR is much better captured by the T341 version of the model, mainly due to a better representation of the scale interaction and the characteristics of IF atmospheric disturbances in the higher-resolution model. The findings here suggest that faithful representations of scale interaction in a global model are critical for modeling and predicting the occurrences of hydrological extremes in the western U.S. and for understanding their potential future changes.

  6. Orion ECLSS/Suit System Intermediate Pressure Integrated Suit Test

    NASA Technical Reports Server (NTRS)

    Barido, Richard A.

    2014-01-01

    The Intermediate Pressure Integrated Suit Test (IPIST) phase of the integrated system testing of the Orion Vehicle Atmosphere Revitalization System (ARS) technology was conducted for the Multipurpose Crew Vehicle (MPCV) Program within the National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate. This test was performed in the eleven-foot human-rated vacuum chamber at the NASA Johnson Space Center by the Crew and Thermal Systems Division. This testing is the second phase of suit loop testing to demonstrate the viability of the Environmental Control and Life Support System (ECLSS) being developed for Orion. The IPIST configuration consisted of development hardware that included the CAMRAS, air revitalization loop fan and suit loop regulator. Two test subjects were in pressure suits at varying suit pressures. Follow-on testing, to be conducted in 2014, will utilize the same hardware with human test subjects in pressure suits at vacuum. This paper will discuss the results and findings of IPIST and will also discuss future testing.

  7. Comparison of High, Intermediate, and Low Frequency Shock Wave Lithotripsy for Urinary Tract Stone Disease: Systematic Review and Network Meta-Analysis

    PubMed Central

    Kang, Dong Hyuk; Cho, Kang Su; Ham, Won Sik; Lee, Hyungmin; Kwon, Jong Kyou; Choi, Young Deuk

    2016-01-01

    Objectives To perform a systematic review and network meta-analysis of randomized controlled trials (RCTs) to determine the optimal shock wave lithotripsy (SWL) frequency range for treating urinary stones, i.e., high-frequency (100–120 waves/minute), intermediate-frequency (80–90 waves/minute), and low-frequency (60–70 waves/minute) lithotripsy. Materials and Methods Relevant RCTs were identified from electronic databases for meta-analysis of SWL success and complication rates. Using pairwise and network meta-analyses, comparisons were made by qualitative and quantitative syntheses. Outcome variables are provided as odds ratios (ORs) with 95% confidence intervals (CIs). Results Thirteen articles were included in the qualitative and quantitative synthesis using pairwise and network meta-analyses. On pairwise meta-analyses, comparable inter-study heterogeneity was observed for the success rate. On network meta-analyses, the success rates of low- (OR 2.2; 95% CI 1.5–2.6) and intermediate-frequency SWL (OR 2.5; 95% CI 1.3–4.6) were higher than high-frequency SWL. Forest plots from the network meta-analysis showed no significant differences in the success rate between low-frequency SWL versus intermediate-frequency SWL (OR 0.87; 95% CI 0.51–1.7). There were no differences in complication rate across different SWL frequency ranges. By rank-probability testing, intermediate-frequency SWL was ranked highest for success rate, followed by low-frequency and high-frequency SWL. Low-frequency SWL was also ranked highest for low complication rate, with high- and intermediate-frequency SWL ranked lower. Conclusions Intermediate- and low-frequency SWL have better treatment outcomes than high-frequency SWL when considering both efficacy and complication. PMID:27387279

  8. Liquefaction processes and systems and liquefaction process intermediate compositions

    DOEpatents

    Schmidt, Andrew J.; Hart, Todd R.; Billing, Justin M.; Maupin, Gary D.; Hallen, Richard T.; Anderson, Daniel B.

    2014-07-12

    Liquefaction processes are provided that can include: providing a biomass slurry solution having a temperature of at least 300.degree. C. at a pressure of at least 2000 psig; cooling the solution to a temperature of less than 150.degree. C.; and depressurizing the solution to release carbon dioxide from the solution and form at least part of a bio-oil foam. Liquefaction processes are also provided that can include: filtering the biomass slurry to remove particulates; and cooling and depressurizing the filtered solution to form the bio-oil foam. Liquefaction systems are provided that can include: a heated biomass slurry reaction zone maintained above 300.degree. C. and at least 2000 psig and in continuous fluid communication with a flash cooling/depressurization zone maintained below 150.degree. C. and between about 125 psig and about atmospheric pressure. Liquefaction systems are also provided that can include a foam/liquid separation system. Liquefaction process intermediate compositions are provided that can include a bio-oil foam phase separated from an aqueous biomass solids solution.

  9. "Intermediate" seed storage physiology: populus as a natural model system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    “Intermediate” seeds are short lived because they have low tolerance to the combined stresses of low moisture and temperature during storage. We hypothesize that intermediate seeds either 1) exhibit intermediate sensitivity to desiccation compared to orthodox and recalcitrant seeds; 2) are damaged b...

  10. "Intermediate" seed storage physiology: populus as a natural model system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    “Intermediate” seeds are short lived because they are sensitive to the combined stresses of low moisture and temperature during storage. We hypothesize that intermediate seeds either 1) exhibit intermediate sensitivity to desiccation compared to orthodox and recalcitrant seeds; 2) are damaged by sub...

  11. High frequency power distribution system

    NASA Technical Reports Server (NTRS)

    Patel, Mikund R.

    1986-01-01

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

  12. Longitudinal impedance of a smooth toroidal chamber at low and intermediate frequencies

    SciTech Connect

    Ng, King-Yuen; Warnock, R.

    1989-03-01

    We evaluate the longitudinal coupling impedance of a toroidal chamber with rectangular cross section in the frequency domain below the synchronous resonant modes. With infinite wall conductivity the impedance is purely reactive and consists of a ''space charge'' term, proportional to ..gamma../sup /minus/2/, and a ''curvature'' term which survives at large ..gamma... The curvature term is well represented as a quadratic function of frequency. 3 refs., 3 figs.

  13. Materials System for Intermediate Temperature Solid Oxide Fuel Cell

    SciTech Connect

    Uday B. Pal; Srikanth Gopalan

    2006-01-12

    The objective of this work was to obtain a stable materials system for intermediate temperature solid oxide fuel cell (SOFC) capable of operating between 600-800 C with a power density greater than 0.2 W/cm{sup 2}. The solid electrolyte chosen for this system was La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3}, (LSGM). To select the right electrode materials from a group of possible candidate materials, AC complex impedance spectroscopy studies were conducted between 600-800 C on symmetrical cells that employed the LSGM electrolyte. Based on the results of the investigation, LSGM electrolyte supported SOFCs were fabricated with La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3}-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSCF-LSGM) composite cathode and Nickel-Ce{sub 0.6}La{sub 0.4}O{sub 3} (Ni-LDC) composite anode having a barrier layer of Ce{sub 0.6}La{sub 0.4}O{sub 3} (LDC) between the LSGM electrolyte and the Ni-LDC anode. Electrical performance and stability of these cells were determined and the electrode polarization behavior as a function of cell current was modeled between 600-800 C. The electrical performance of the anode-supported SOFC was simulated assuming an electrode polarization behavior identical to the LSGM-electrolyte-supported SOFC. The simulated electrical performance indicated that the selected material system would provide a stable cell capable of operating between 600-800 C with a power density between 0.2 to 1 W/cm{sup 2}.

  14. Nanoelectromechanical systems: Nanodevice motion at microwave frequencies

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

  15. Materials System for Intermediate Temperature Solid Oxide Fuel Cell

    SciTech Connect

    Uday B. Pal; Srikanth Gopalan

    2005-01-24

    AC complex impedance spectroscopy studies were conducted between 600-800 C on symmetrical cells that employed strontium-and-magnesium-doped lanthanum gallate electrolyte, La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSGM). The objective of the study was to identify the materials system for fabrication and evaluation of intermediate temperature (600-800 C) solid oxide fuel cells (SOFCs). The slurry-coated electrode materials had fine porosity to enhance catalytic activity. Cathode materials investigated include La{sub 1-x}Sr{sub x}MnO{sub 3} (LSM), LSCF (La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3}), a two-phase particulate composite consisting of LSM-doped-lanthanum gallate (LSGM), and LSCF-LSGM. The anode materials were Ni-Ce{sub 0.85}Gd{sub 0.15}O{sub 2} (Ni-GDC) and Ni-Ce{sub 0.6}La{sub 0.4}O{sub 2} (Ni-LDC) composites. Experiments conducted with the anode materials investigated the effect of having a barrier layer of GDC or LDC in between the LSGM electrolyte and the Ni-composite anode to prevent adverse reaction of the Ni with lanthanum in LSGM. For proper interpretation of the beneficial effects of the barrier layer, similar measurements were performed without the barrier layer. The ohmic and the polarization resistances of the system were obtained over time as a function of temperature (600-800 C), firing temperature, thickness, and the composition of the electrodes. The study revealed important details pertaining to the ohmic and the polarization resistances of the electrode as they relate to stability and the charge-transfer reactions that occur in such electrode structures.

  16. Racah materials: role of atomic multiplets in intermediate valence systems

    PubMed Central

    Shick, A. B.; Havela, L.; Lichtenstein, A. I.; Katsnelson, M. I.

    2015-01-01

    We address the long-standing mystery of the nonmagnetic insulating state of the intermediate valence compound SmB6. Within a combination of the local density approximation (LDA) and an exact diagonalization (ED) of an effective discrete Anderson impurity model, the intermediate valence ground state with the f-shell occupation 〈n4f〉 = 5.6 is found for the Sm atom in SmB6. This ground state is a singlet, and the first excited triplet state ~3 meV higher in the energy. SmB6 is a narrow band insulator already in LDA, with the direct band gap of ~10 meV. The electron correlations increase the band gap which now becomes indirect. Thus, the many-body effects are relevant to form the indirect band gap, crucial for the idea of “topological Kondo insulator" in SmB6. Also, an actinide analog PuB6 is considered, and the intermediate valence singlet ground state is found for the Pu atom. We propose that [Sm, Pu]B6 belong to a new class of the intermediate valence materials with the multi-orbital “Kondo-like" singlet ground-state. Crucial role of complex spin-orbital f  n–f  n+1 multiplet structure differently hybridized with ligand states in such Racah materials is discussed. PMID:26490021

  17. MIMO system identification using frequency response data

    NASA Technical Reports Server (NTRS)

    Medina, Enrique A.; Irwin, R. D.; Mitchell, Jerrel R.; Bukley, Angelia P.

    1992-01-01

    A solution to the problem of obtaining a multi-input, multi-output statespace model of a system from its individual input/output frequency responses is presented. The Residue Identification Algorithm (RID) identifies the system poles from a transfer function model of the determinant of the frequency response data matrix. Next, the residue matrices of the modes are computed guaranteeing that each input/output frequency response is fitted in the least squares sense. Finally, a realization of the system is computed. Results of the application of RID to experimental frequency responses of a large space structure ground test facility are presented and compared to those obtained via the Eigensystem Realization Algorithm.

  18. Occupational exposures to high frequency electromagnetic fields in the intermediate range ( >300 Hz-10 MHz).

    PubMed

    Floderus, Birgitta; Stenlund, Carin; Carlgren, Frank

    2002-12-01

    The aim of this study was to identify work situations with electromagnetic fields of 300 Hz-10 MHz and to characterize the occupational exposure. Work place investigations included descriptions of the work environment and physical measurements. We estimated electric (E) and magnetic (H) fields by spot measurements in air, by logged exposure data, and when possible, we recorded induced currents in limbs. The instruments used were Wandel and Golterman EFA-3, NARDA 8718, Holaday HI-3702. The exposure sources comprised five induction furnaces, seven induction heaters, one surface treatment equipment, four units of electronic article surveillance (EAS), and medical devices for surgery and muscle stimulation. The induction furnaces operated at 480 Hz-7 kHz, and the maximum values of logged data varied between 512-2,093 V/m (E field) and 10.5-87.3 A/m (H field). The induction heaters (3.8 kHz-1.25 MHz) also showed high maximum exposure values of both E and H fields. Three EAS units, an electromagnetic plate at a library, a luggage control unit, and an antitheft gate, showed E fields reaching 658-1,069 V/m. The H fields were comparatively lower, except for the antitheft gate (5 and 7.5 kHz) showing a maximum value of 27.2 A/m (recorded during repair). Induced currents of 5-13 mA were measured for the medical devices. The study improves the basis for an exposure assessment for epidemiological studies of long term effects of exposures to high frequency electromagnetic fields. PMID:12395411

  19. Seismic isolation systems with distinct multiple frequencies

    DOEpatents

    Wu, Ting-shu; Seidensticker, Ralph W.

    1990-01-01

    A method and apparatus for isolating a building or other structure from smic vibratory motion which provides increased assurance that large horizontal motion of the structure will not occur than is provided by other isolation systems. Increased assurance that large horizontal motion will not occur is achieved by providing for change of the natural frequency of the support and structure system in response to displacement of the structure beyond a predetermined value. The natural frequency of the support and structure system may be achieved by providing for engaging and disengaging of the structure and some supporting members in response to motion of the supported structure.

  20. Digital Intermediate Frequency Receiver Module For Use In Airborne Sar Applications

    DOEpatents

    Tise, Bertice L.; Dubbert, Dale F.

    2005-03-08

    A digital IF receiver (DRX) module directly compatible with advanced radar systems such as synthetic aperture radar (SAR) systems. The DRX can combine a 1 G-Sample/sec 8-bit ADC with high-speed digital signal processor, such as high gate-count FPGA technology or ASICs to realize a wideband IF receiver. DSP operations implemented in the DRX can include quadrature demodulation and multi-rate, variable-bandwidth IF filtering. Pulse-to-pulse (Doppler domain) filtering can also be implemented in the form of a presummer (accumulator) and an azimuth prefilter. An out of band noise source can be employed to provide a dither signal to the ADC, and later be removed by digital signal processing. Both the range and Doppler domain filtering operations can be implemented using a unique pane architecture which allows on-the-fly selection of the filter decimation factor, and hence, the filter bandwidth. The DRX module can include a standard VME-64 interface for control, status, and programming. An interface can provide phase history data to the real-time image formation processors. A third front-panel data port (FPDP) interface can send wide bandwidth, raw phase histories to a real-time phase history recorder for ground processing.

  1. Frequency and properties of bars in cluster and field galaxies at intermediate redshifts

    NASA Astrophysics Data System (ADS)

    Barazza, F. D.; Jablonka, P.; Desai, V.; Jogee, S.; Aragón-Salamanca, A.; De Lucia, G.; Saglia, R. P.; Halliday, C.; Poggianti, B. M.; Dalcanton, J. J.; Rudnick, G.; Milvang-Jensen, B.; Noll, S.; Simard, L.; Clowe, D. I.; Pelló, R.; White, S. D. M.; Zaritsky, D.

    2009-04-01

    We present a study of large-scale bars in field and cluster environments out to redshifts of ~0.8 using a final sample of 945 moderately inclined disk galaxies drawn from the EDisCS project. We characterize bars and their host galaxies and look for relations between the presence of a bar and the properties of the underlying disk. We investigate whether the fraction and properties of bars in clusters are different from their counterparts in the field. The properties of bars and disks are determined by ellipse fits to the surface brightness distribution of the galaxies using HST/ACS images in the F814W filter. The bar identification is based on quantitative criteria after highly inclined (> 60°) systems have been excluded. The total optical bar fraction in the redshift range z = 0.4-0.8 (median z = 0.60), averaged over the entire sample, is 25% (20% for strong bars). For the cluster and field subsamples, we measure bar fractions of 24% and 29%, respectively. We find that bars in clusters are on average longer than in the field and preferentially found close to the cluster center, where the bar fraction is somewhat higher (~31%) than at larger distances (~18%). These findings however rely on a relatively small subsample and might be affected by small number statistics. In agreement with local studies, we find that disk-dominated galaxies have a higher optical bar fraction (~45%) than bulge-dominated galaxies (~15%). This result is based on Hubble types and effective radii and does not change with redshift. The latter finding implies that bar formation or dissolution is strongly connected to the emergence of the morphological structure of a disk and is typically accompanied by a transition in the Hubble type. The question whether internal or external factors are more important for bar formation and evolution cannot be answered definitely. On the one hand, the bar fraction and properties of cluster and field samples of disk galaxies are quite similar, indicating that

  2. MATERIALS SYSTEM FOR INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELL

    SciTech Connect

    Uday B. Pal; Srikanth Gopalan

    2004-02-15

    AC complex impedance spectroscopy studies were conducted on symmetrical cells of the type [gas, electrode/LSGM electrolyte/electrode, gas]. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support. The electrodes selected for this investigation are candidate materials for SOFC electrodes. Cathode materials include La{sub 1-x}Sr{sub x}MnO{sub 3} (LSM), LSCF (La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3}), a two-phase particulate composite consisting of LSM + doped-lanthanum gallate (LSGM), and LSCF + LSGM. Pt metal electrodes were also used for the purpose of comparison. Anode material investigated was the Ni + GDC composite. The study revealed important details pertaining to the charge-transfer reactions that occur in such electrodes. The information obtained can be used to design electrodes for intermediate temperature SOFCs based on LSGM electrolyte.

  3. Frequency domain state-space system identification

    NASA Technical Reports Server (NTRS)

    Chen, Chung-Wen; Juang, Jer-Nan; Lee, Gordon

    1992-01-01

    An algorithm for identifying state-space models from frequency response data of linear systems is presented. A matrix-fraction description of the transfer function is employed to curve-fit the frequency response data, using the least-squares method. The parameters of the matrix-fraction representation are then used to construct the Markov parameters of the system. Finally, state-space models are obtained through the Eigensystem Realization Algorithm using Markov parameters. The main advantage of this approach is that the curve-fitting and the Markov parameter construction are linear problems which avoid the difficulties of nonlinear optimization of other approaches. Another advantage is that it avoids windowing distortions associated with other frequency domain methods.

  4. Odd-frequency Superconductivity in Driven Systems

    NASA Astrophysics Data System (ADS)

    Triola, Christopher; Balatsky, Alexander

    We show that Berezinskii's classification of the symmetries of Cooper pair amplitudes in terms of parity under transformations that invert spin, space, time, and orbital degrees of freedom holds for driven systems even in the absence of translation invariance. We then discuss the conditions under which pair amplitudes which are odd in frequency can emerge in driven systems. Considering a model Hamiltonian for a superconductor coupled to an external driving potential, we investigate the influence of the drive on the anomalous Green's function, density of states, and spectral function. We find that the anomalous Green's function develops odd in frequency component in the presence of an external drive. Furthermore we investigate how these odd-frequency terms are related to satellite features in the density of states and spectral function. Supported by US DOE BES E 304.

  5. SYNCHROTRON RADIO FREQUENCY PHASE CONTROL SYSTEM

    DOEpatents

    Plotkin, M.; Raka, E.C.; Snyder, H.S.

    1963-05-01

    A system for canceling varying phase changes introduced by connecting cables and control equipment in an alternating gradient synchrotron is presented. In a specific synchrotron embodiment twelve spaced accelerating stations for the proton bunches are utilized. In order to ensure that the protons receive their boost or kick at the exact instant necessary it is necessary to compensate for phase changes occurring in the r-f circuitry over the wide range of frequencies dictated by the accelerated velocities of the proton bunches. A constant beat frequency is utilized to transfer the r-f control signals through the cables and control equipment to render the phase shift constant and readily compensable. (AEC)

  6. Distinguishing defect induced intermediate frequency modes from combination modes in the Raman spectrum of single walled carbon nanotubes

    SciTech Connect

    Singh, Dilip K.; Iyer, Parameswar K.; Giri, P. K.

    2012-03-15

    Understanding of the origin of some of the intermediate frequency modes (IFMs) in the Raman spectrum of carbon nanotubes has remained controversial in the literature. In this work, through controlled introduction and elimination of defects in carbon nanotubes, we attempt to isolate the IFMs due to structural defects from that of the combination modes in single walled carbon nanotubes (SWCNTs). Our investigations on pristine and defect engineered SWCNTs using ion-irradiation, thermal annealing, and laser processing show systematic changes in the IFMs in the range 400-1200 cm{sup -1} and its manipulation with the processing parameters. In particular, we found that the intensity of IFM at 929 cm{sup -1} scale up with the increasing defect concentration, while that at 668 cm{sup -1} follows opposite behavior. New IFM peaks were observed upon the creation of a controlled amount of structural defects through 30 keV N{sup +} ion irradiation. Elimination of defects through vacuum annealing results into reduction of intensity of some IFMs identified as defect related, while the intensity of characteristic combination modes correspondingly increases. Our results show that the IFMs observed at 709, 805, 868, 926, and 1189 cm{sup -1} are due to structural defects in the SWCNTs, while those in the range 400-550 cm{sup -1} and at 669 cm{sup -1} are due to the combination modes. Our x-ray photoelectron spectroscopy analysis on ion irradiated SWCNTs supports the Raman results.

  7. Single frequency RF powered ECG telemetry system

    NASA Technical Reports Server (NTRS)

    Ko, W. H.; Hynecek, J.; Homa, J.

    1979-01-01

    It has been demonstrated that a radio frequency magnetic field can be used to power implanted electronic circuitry for short range telemetry to replace batteries. A substantial reduction in implanted volume can be achieved by using only one RF tank circuit for receiving the RF power and transmitting the telemetered information. A single channel telemetry system of this type, using time sharing techniques, was developed and employed to transmit the ECG signal from Rhesus monkeys in primate chairs. The signal from the implant is received during the period when the RF powering radiation is interrupted. The ECG signal is carried by 20-microsec pulse position modulated pulses, referred to the trailing edge of the RF powering pulse. Satisfactory results have been obtained with this single frequency system. The concept and the design presented may be useful for short-range long-term implant telemetry systems.

  8. Initial detailed designs for intermediate photovoltaic systems: Office building

    NASA Astrophysics Data System (ADS)

    Herz, J.; Obrien, G.

    1982-07-01

    A detailed design is presented for a 140 kW ground mounted flat plate array photovoltaic system to serve a three story office building. The design is analyzed for performance and economics. Building architectural features and load demands are defined. Photovoltaic array, electrical system design, and system installation are discussed, along with alternative design choices. Specifications and installation details are included.

  9. Automotive Electrical and Electronic System II; Automotive Mechanics-Intermediate: 9045.04.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This automotive electrical and electronic system course is an intermediate course designed for the student who has completed automotive Electrical and Electronic System I. The theory and principles of operation of the components of the starting and charging systems and other electrical accessory systems in the automobile will be learned by the…

  10. Static Frequency Converter System Installed and Tested

    NASA Technical Reports Server (NTRS)

    Brown, Donald P.; Sadhukhan, Debashis

    2003-01-01

    A new Static Frequency Converter (SFC) system has been installed and tested at the NASA Glenn Research Center s Central Air Equipment Building to provide consistent, reduced motor start times and improved reliability for the building s 14 large exhausters and compressors. The operational start times have been consistent around 2 min, 20 s per machine. This is at least a 3-min improvement (per machine) over the old variable-frequency motor generator sets. The SFC was designed and built by Asea Brown Boveri (ABB) and installed by Encompass Design Group (EDG) as part of a Construction of Facilities project managed by Glenn (Robert Scheidegger, project manager). The authors designed the Central Process Distributed Control Systems interface and control between the programmable logic controller, solid-state exciter, and switchgear, which was constructed by Gilcrest Electric.

  11. Standard infralow-frequency vibration system

    SciTech Connect

    Chistyakov, V.A.; Korytko, E.P.; Pevzner, B.N.; Prosikov, A.A.

    1985-06-01

    Precision test systems working in the range 0.01-20 Hz are required to determine the metrological characteristics of seismic equipment used in seismic observations and in research on the earth's physical properties. An experimental seismometric test system (STS) has been built to produce sinusoidal oscillations in the horizontal plane in the range 0.01-20 Hz with amplitudes of 0.1-20 mm for instruments of mass up to 25 kg. The apparatus contains a computer and the programmable GZ-110 oscillator, which provide good scope for automating the processing and specifying the working modes in checking equipment with high accuracy and throughput. The STS enables one to record the frequency response, the phase response, and the amplitude characteristics for means of measuring the parameters of infralow-frequency vibrations, as well as to determine the conversion factors for seismic detectors and the metrological parameters of instruments.

  12. Optimal System Realization in Frequency Domain

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Maghami, Peiman G.

    1999-01-01

    Several approaches are presented to identify an experimental system model directly from frequency response data. The formulation begins with a matrix-fraction description as the model structure. Frequency weighting such as exponential weighting is introduced to solve a weighted least-squares problem to obtain the coefficient matrices for the matrix-fraction description. A multi-variable state-space model can then be formed using the coefficient matrices of the matrix-fraction description. An approach is introduced to fine-tune the model using non-linear programming methods to minimize the desired cost function. The method deals with the model in the real Schur or modal form and reassigns a subset of system poles using a nonlinear optimizer. At every optimization step, the input and output influence matrices are refined through least-squares procedures. The proposed approaches are used to identify an analytical model for a NASA testbed from experimental data.

  13. Initial detailed designs for intermediate photovoltaic systems: Bottling plant

    NASA Astrophysics Data System (ADS)

    Herz, J.; Obrien, G.

    1982-08-01

    The detailed design of a 155 kW roof mounted PV-thermal concentrating array system is described and is analyzed for performance and economics. The building architectural features and load demands of the bottling plant are defined, and photovoltaic array, electrical system design, and system installation are defined and discussed. Alternative mechanical design choices are also presented. Appended are a drawing set list, specifications, and installation details.

  14. Running, hopping and trotting: tuning step frequency to the resonant frequency of the bouncing system favors larger animals.

    PubMed

    Cavagna, Giovanni A; Legramandi, Mario A

    2015-10-01

    A long-lasting challenge in comparative physiology is to understand why the efficiency of the mechanical work done to maintain locomotion increases with body mass. It has been suggested that this is due to a more elastic step in larger animals. Here, we show in running, hopping and trotting animals, and in human running during growth, that the resonant frequency of the bouncing system decreases with increasing body mass and is, surprisingly, independent of species or gait. Step frequency roughly equals the resonant frequency in trotting and running, whereas it is about half the resonant frequency in hopping. The energy loss by elastic hysteresis during loading and unloading the bouncing system from its equilibrium position decreases with increasing body mass. Similarity to a symmetrical bounce increases with increasing body mass and, for a given body mass, seems to be maximal in hopping, intermediate in trotting and minimal in running. We conclude that: (1) tuning step frequency to the resonant frequency of the bouncing system coincides with a lower hysteresis loss in larger, more-compliant animals; (2) the mechanism of gait per se affects similarity with a symmetrical bounce, independent of hysteresis; and (3) the greater efficiency in larger animals may be due, at least in part, to a lower hysteresis loss. PMID:26347555

  15. Collaborative Project. Mode and Intermediate Waters in Earth System Models

    SciTech Connect

    Sarmiento, Jorge L.; Dufour, Carolina; Rodgers, Keith B.

    2015-12-16

    The focus of this grant was on diagnosing the physical mechanisms controlling upper ocean water mass formation and carbon distribution in Earth System Models (ESMs), with the goal of improving the physics that controls their formation.

  16. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-12-31

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  17. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-10-01

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  18. Study of photovoltaic cost elements. Volume 5: Installation cost model for intermediate PV systems: Users manual

    NASA Astrophysics Data System (ADS)

    Ayers, J. B.

    1981-07-01

    A cost modeling methodology is presented for estimating installation costs associated with intermediate photovoltaic (PV) systems. With only a parametric description of an intermediate power system, the model can be used to develop an installation cost estimate for that system. The model is based on conventional cost-estimating procedures widely used by the construction industry and was validated by comparing estimates for the same 10 systems made independently by a cost engineering firm. A description of the model is included as well as an example of its use with a 200 KW solar breeder plant design to be located in Rockville, Maryland.

  19. Early Exposure to Intermediate-Frequency Magnetic Fields Alters Brain Biomarkers without Histopathological Changes in Adult Mice

    PubMed Central

    Win-Shwe, Tin-Tin; Ohtani, Shin; Ushiyama, Akira; Kunugita, Naoki

    2015-01-01

    Recently we have reported that intermediate-frequency magnetic field (IF-MF) exposure transiently altered the mRNA expression levels of memory function-related genes in the hippocampi of adult male mice. However, the effects of IF-MF exposure during brain development on neurological biomarkers have not yet been clarified. In the present study, we investigated the effect of IF-MF exposure during development on neurological and immunological markers in the mouse hippocampus in 3- and 7-week-old male mice. Pregnant C57BL/6J mice were exposed to IF-MF (21 kHz, 3.8 mT) for one hour per day from organogenesis period day 7 to 17. At adolescence, some IF-MF-exposed mice were further divided into exposure, recovery, and sham-exposure groups. The adolescent-exposure groups were exposed again to IF-MF from postnatal day 27 to 48. The expression of mRNA in the hippocampi was examined using a real-time RT-PCR method, and microglia activation was examined by immunohistochemical analysis. The expression levels of NR1 and NR2B as well as transcription factors (CaMKIV, CREB1), inflammatory mediators (COX2, IL-1 β,TNF-α), and the oxidative stress marker heme-oxygenase (HO)-1 were significantly increased in the IF-MF-exposed mice, compared with the control group, in the 7-week-old mice, but not in the 3-week-old mice. Microglia activation was not different between the control and other groups. This study provides the first evidence that early exposure to IF-MF reversibly affects the NMDA receptor, its related signaling pathways, and inflammatory mediators in the hippocampus of young adult mice; these changes are transient and recover after termination of exposure without histopathological changes. PMID:25913185

  20. Early exposure to intermediate-frequency magnetic fields alters brain biomarkers without histopathological changes in adult mice.

    PubMed

    Win-Shwe, Tin-Tin; Ohtani, Shin; Ushiyama, Akira; Kunugita, Naoki

    2015-04-01

    Recently we have reported that intermediate-frequency magnetic field (IF-MF) exposure transiently altered the mRNA expression levels of memory function-related genes in the hippocampi of adult male mice. However, the effects of IF-MF exposure during brain development on neurological biomarkers have not yet been clarified. In the present study, we investigated the effect of IF-MF exposure during development on neurological and immunological markers in the mouse hippocampus in 3- and 7-week-old male mice. Pregnant C57BL/6J mice were exposed to IF-MF (21 kHz, 3.8 mT) for one hour per day from organogenesis period day 7 to 17. At adolescence, some IF-MF-exposed mice were further divided into exposure, recovery, and sham-exposure groups. The adolescent-exposure groups were exposed again to IF-MF from postnatal day 27 to 48. The expression of mRNA in the hippocampi was examined using a real-time RT-PCR method, and microglia activation was examined by immunohistochemical analysis. The expression levels of NR1 and NR2B as well as transcription factors (CaMKIV, CREB1), inflammatory mediators (COX2, IL-1 b,TNF-α), and the oxidative stress marker heme-oxygenase (HO)-1 were significantly increased in the IF-MF-exposed mice, compared with the control group, in the 7-week-old mice, but not in the 3-week-old mice. Microglia activation was not different between the control and other groups. This study provides the first evidence that early exposure to IF-MF reversibly affects the NMDA receptor, its related signaling pathways, and inflammatory mediators in the hippocampus of young adult mice; these changes are transient and recover after termination of exposure without histopathological changes. PMID:25913185

  1. A highly triaxial N-body system tumbling about is intermediate axis

    NASA Technical Reports Server (NTRS)

    Duncan, Martin J.; Levison, Harold F.

    1989-01-01

    The results are presented of an N-body simulation which shows that it is possible for a highly triaxial self-gravitating system in dynamical equilibrium to exhibit stable figure rotation about its intermediate axis. The system is long-lived, lasting at least 20 half-mass crossing times of the final system. The nature of the simulation is summarized.

  2. A Walk through TRIDEC's intermediate Tsunami Early Warning System

    NASA Astrophysics Data System (ADS)

    Hammitzsch, M.; Reißland, S.; Lendholt, M.

    2012-04-01

    The management of natural crises is an important application field of the technology developed in the project Collaborative, Complex, and Critical Decision-Support in Evolving Crises (TRIDEC), co-funded by the European Commission in its Seventh Framework Programme. TRIDEC is based on the development of the German Indonesian Tsunami Early Warning System (GITEWS) and the Distant Early Warning System (DEWS) providing a service platform for both sensor integration and warning dissemination. In TRIDEC new developments in Information and Communication Technology (ICT) are used to extend the existing platform realising a component-based technology framework for building distributed tsunami warning systems for deployment, e.g. in the North-eastern Atlantic, the Mediterranean and Connected Seas (NEAM) region. The TRIDEC system will be implemented in three phases, each with a demonstrator. Successively, the demonstrators are addressing challenges, such as the design and implementation of a robust and scalable service infrastructure supporting the integration and utilisation of existing resources with accelerated generation of large volumes of data. These include sensor systems, geo-information repositories, simulation tools and data fusion tools. In addition to conventional sensors also unconventional sensors and sensor networks play an important role in TRIDEC. The system version presented is based on service-oriented architecture (SOA) concepts and on relevant standards of the Open Geospatial Consortium (OGC), the World Wide Web Consortium (W3C) and the Organization for the Advancement of Structured Information Standards (OASIS). In this way the system continuously gathers, processes and displays events and data coming from open sensor platforms to enable operators to quickly decide whether an early warning is necessary and to send personalized warning messages to the authorities and the population at large through a wide range of communication channels. The system

  3. Legacy Vehicle Fuel System Testing with Intermediate Ethanol Blends

    SciTech Connect

    Davis, G. W.; Hoff, C. J.; Borton, Z.; Ratcliff, M. A.

    2012-03-01

    The effects of E10 and E17 on legacy fuel system components from three common mid-1990s vintage vehicle models (Ford, GM, and Toyota) were studied. The fuel systems comprised a fuel sending unit with pump, a fuel rail and integrated pressure regulator, and the fuel injectors. The fuel system components were characterized and then installed and tested in sample aging test rigs to simulate the exposure and operation of the fuel system components in an operating vehicle. The fuel injectors were cycled with varying pulse widths during pump operation. Operational performance, such as fuel flow and pressure, was monitored during the aging tests. Both of the Toyota fuel pumps demonstrated some degradation in performance during testing. Six injectors were tested in each aging rig. The Ford and GM injectors showed little change over the aging tests. Overall, based on the results of both the fuel pump testing and the fuel injector testing, no major failures were observed that could be attributed to E17 exposure. The unknown fuel component histories add a large uncertainty to the aging tests. Acquiring fuel system components from operational legacy vehicles would reduce the uncertainty.

  4. Extreme low frequency acoustic measurement system

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)

    2013-01-01

    The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.

  5. Optimum frequency assignment for satellite SCPC systems

    NASA Astrophysics Data System (ADS)

    Okinaka, H.; Yasuda, Y.; Hirata, Y.

    A technique for deriving a quasi-optimum solution for IM-minimum channel allocation for single-level SCPC systems is presented. Two types of IM products are considered as the dominant components in an RF band. The third order IM product is proportional to the product of the power of concerned carriers, allowing a weighting function to be defined for calculating the IM noise. An IM minimum channel allocation technique can then be used to reduce the IM noise occurring in the carrier slots through frequency assignment. The worst carrier is automatically deleted with an initial channel allocation and the process is iterated until the maximum noise reduction is obtained. The first two or three carriers are assigned to unused frequency slots with low noise. The method is also viable when dealing with a larger number of carriers.

  6. Scanned Image Projection System Employing Intermediate Image Plane

    NASA Technical Reports Server (NTRS)

    DeJong, Christian Dean (Inventor); Hudman, Joshua M. (Inventor)

    2014-01-01

    In imaging system, a spatial light modulator is configured to produce images by scanning a plurality light beams. A first optical element is configured to cause the plurality of light beams to converge along an optical path defined between the first optical element and the spatial light modulator. A second optical element is disposed between the spatial light modulator and a waveguide. The first optical element and the spatial light modulator are arranged such that an image plane is created between the spatial light modulator and the second optical element. The second optical element is configured to collect the diverging light from the image plane and collimate it. The second optical element then delivers the collimated light to a pupil at an input of the waveguide.

  7. A high frequency electromagnetic impedance imaging system

    SciTech Connect

    Tseng, Hung-Wen; Lee, Ki Ha; Becker, Alex

    2003-01-15

    Non-invasive, high resolution geophysical mapping of the shallow subsurface is necessary for delineation of buried hazardous wastes, detecting unexploded ordinance, verifying and monitoring of containment or moisture contents, and other environmental applications. Electromagnetic (EM) techniques can be used for this purpose since electrical conductivity and dielectric permittivity are representative of the subsurface media. Measurements in the EM frequency band between 1 and 100 MHz are very important for such applications, because the induction number of many targets is small and the ability to determine the subsurface distribution of both electrical properties is required. Earlier workers were successful in developing systems for detecting anomalous areas, but quantitative interpretation of the data was difficult. Accurate measurements are necessary, but difficult to achieve for high-resolution imaging of the subsurface. We are developing a broadband non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using an EM impedance approach similar to the MT exploration technique. Electric and magnetic sensors were tested to ensure that stray EM scattering is minimized and the quality of the data collected with the high-frequency impedance (HFI) system is good enough to allow high-resolution, multi-dimensional imaging of hidden targets. Additional efforts are being made to modify and further develop existing sensors and transmitters to improve the imaging capability and data acquisition efficiency.

  8. High-frequency laser sonar system

    NASA Astrophysics Data System (ADS)

    Cray, Benjamin A.; Sarma, Ashwin; Kirsteins, Ivars P.

    2002-11-01

    A set of measurements recently completed at the Naval Undersea Warfare Center (NUWC) demonstrated that a laser-based sonar system can be used to detect acoustic particle velocity on the surface of a thin acoustically-compliant plate embedded beneath a standard acoustic window. The theoretical acoustic and measured surface particle velocity varied by less than 1 dB (reference m/s) over a wide frequency band (10 kHz to 100 kHz). However, the Polytec Model PSV-100 Scanning Laser Vibrometer System (SLVS) used in the experiments had relatively poor acoustic sensitivity, presumably due to high electronic noise, speckle noise, stand-off distance, and drifting laser focus. The laser's acoustic sensitivity appears to be inversely proportional to the backscatter signal level. The existing SLVS can sample a grid of 512 by 512 points, with each grid point having a spot size of approximately 10 mm (0.0004 in.). Such fine sampling may be used to create essentially a continuous aperture, eliminating acoustic grating lobes at all frequencies of practical sonar interest.

  9. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated... System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies for automated systems....

  10. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated... System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies for automated systems....

  11. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated... System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies for automated systems....

  12. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated... System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies for automated systems....

  13. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated... System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for automated systems....

  14. Carrier: Interference ratios for frequency sharing between satellite systems transmitting frequency modulated and digital television signals

    NASA Technical Reports Server (NTRS)

    Barnes, S. P.

    1979-01-01

    Results are presented of subjective and quantitative tests describing the results of interference to a particular digital television system from a frequency modulated (FM) television system, and for interference to an FM television system from a digital television system.

  15. Sustainable Thorium Nuclear Fuel Cycles: A Comparison of Intermediate and Fast Neutron Spectrum Systems

    DOE PAGESBeta

    Brown, Nicholas R.; Powers, Jeffrey J.; Feng, B.; Heidet, F.; Stauff, N.; Zhang, G.; Todosow, Michael; Worrall, Andrew; Gehin, Jess C.; Kim, T. K.; et al

    2015-05-21

    This paper presents analyses of possible reactor representations of a nuclear fuel cycle with continuous recycling of thorium and produced uranium (mostly U-233) with thorium-only feed. The analysis was performed in the context of a U.S. Department of Energy effort to develop a compendium of informative nuclear fuel cycle performance data. The objective of this paper is to determine whether intermediate spectrum systems, having a majority of fission events occurring with incident neutron energies between 1 eV and 105 eV, perform as well as fast spectrum systems in this fuel cycle. The intermediate spectrum options analyzed include tight lattice heavymore » or light water-cooled reactors, continuously refueled molten salt reactors, and a sodium-cooled reactor with hydride fuel. All options were modeled in reactor physics codes to calculate their lattice physics, spectrum characteristics, and fuel compositions over time. Based on these results, detailed metrics were calculated to compare the fuel cycle performance. These metrics include waste management and resource utilization, and are binned to accommodate uncertainties. The performance of the intermediate systems for this selfsustaining thorium fuel cycle was similar to a representative fast spectrum system. However, the number of fission neutrons emitted per neutron absorbed limits performance in intermediate spectrum systems.« less

  16. Sustainable Thorium Nuclear Fuel Cycles: A Comparison of Intermediate and Fast Neutron Spectrum Systems

    SciTech Connect

    Brown, Nicholas R.; Powers, Jeffrey J.; Feng, B.; Heidet, F.; Stauff, N.; Zhang, G.; Todosow, Michael; Worrall, Andrew; Gehin, Jess C.; Kim, T. K.; Taiwo, T. A.

    2015-05-21

    This paper presents analyses of possible reactor representations of a nuclear fuel cycle with continuous recycling of thorium and produced uranium (mostly U-233) with thorium-only feed. The analysis was performed in the context of a U.S. Department of Energy effort to develop a compendium of informative nuclear fuel cycle performance data. The objective of this paper is to determine whether intermediate spectrum systems, having a majority of fission events occurring with incident neutron energies between 1 eV and 105 eV, perform as well as fast spectrum systems in this fuel cycle. The intermediate spectrum options analyzed include tight lattice heavy or light water-cooled reactors, continuously refueled molten salt reactors, and a sodium-cooled reactor with hydride fuel. All options were modeled in reactor physics codes to calculate their lattice physics, spectrum characteristics, and fuel compositions over time. Based on these results, detailed metrics were calculated to compare the fuel cycle performance. These metrics include waste management and resource utilization, and are binned to accommodate uncertainties. The performance of the intermediate systems for this selfsustaining thorium fuel cycle was similar to a representative fast spectrum system. However, the number of fission neutrons emitted per neutron absorbed limits performance in intermediate spectrum systems.

  17. Seismic isolation systems designed with distinct multiple frequencies

    SciTech Connect

    Wu, Ting-shu; Seidensticker, R.W.

    1991-01-01

    Two systems for seismic base isolation are presented. The main feature of these system is that, instead of only one isolation frequency as in conventional isolation systems, they are designed to have two distinct isolation frequencies. When the responses during an earthquake exceed the design value(s), the system will automatically and passively shift to the secondly isolation frequency. Responses of these two systems to different ground motions including a harmonic motion with frequency same as the primary isolation frequency, show that no excessive amplification will occur. Adoption of these new systems certainly will greatly enhance the safety and reliability of an isolated superstructure against future strong earthquakes. 3 refs.

  18. Seismic isolation systems designed with distinct multiple frequencies

    SciTech Connect

    Wu, Ting-shu; Seidensticker, R.W.

    1991-12-31

    Two systems for seismic base isolation are presented. The main feature of these system is that, instead of only one isolation frequency as in conventional isolation systems, they are designed to have two distinct isolation frequencies. When the responses during an earthquake exceed the design value(s), the system will automatically and passively shift to the secondly isolation frequency. Responses of these two systems to different ground motions including a harmonic motion with frequency same as the primary isolation frequency, show that no excessive amplification will occur. Adoption of these new systems certainly will greatly enhance the safety and reliability of an isolated superstructure against future strong earthquakes. 3 refs.

  19. Construction of a tunable multi-enzyme-coordinate expression system for biosynthesis of chiral drug intermediates

    PubMed Central

    Jiang, Wei; Fang, Baishan

    2016-01-01

    Systems that can regulate and coordinate the expression of multiple enzymes for metabolic regulation and synthesis of important drug intermediates are poorly explored. In this work, a strategy for constructing a tunable multi-enzyme-coordinate expression system for biosynthesis of chiral drug intermediates was developed and evaluated by connecting protein-protein expressions, regulating the strength of ribosome binding sites (RBS) and detecting the system capacity for producing chiral amino acid. Results demonstrated that the dual-enzyme system had good enantioselectivity, low cost, high stability, high conversion rate and approximately 100% substrate conversion. This study has paved a new way of exploring metabolic mechanism of functional genes and engineering whole cell-catalysts for synthesis of chiral α-hydroxy acids or chiral amino acids. PMID:27456301

  20. Retrofit photovoltaic systems for intermediate sized applications-A design and market study

    SciTech Connect

    Noel, G.T.; Hagely, J.R.

    1982-09-01

    An assessment of the technical and economic feasibility of retrofitting a significant portion of the existing intermediate sector building/application inventory with photovoltaic systems is presented. The assessment includes the development of detailed engineering and architectural designs as well as cost estimates for 12 representative installations. Promising applications include retail stores, warehouses, office buildings, religious buildings, shopping centers, education buildings, hospitals, and industrial sites. A market study indicates that there is a national inventory of 1.5 to 2.0 million feasible intermediate sector applications, with the majority being in the 20 to 400 kW size range. The present cost of the major systems components and the cost of necessary building modifications are the primary current barriers to the realization of a large retrofit photovoltaic system market. The development of standardized modular system designs and installation techniques are feasible ways to minimize costs.

  1. General frequency response program calculates frequency response of system, open at any specified element

    NASA Technical Reports Server (NTRS)

    Prosch, J.

    1967-01-01

    The general frequency response program provides the frequency response of any linear feedback control system including the open loop control system. The system characteristic matrix, obtained from the Laplace transformations of the dynamic and control equations, is input to the program. A variety of outputs are available.

  2. Sub-millimeter wave frequency heterodyne detector system

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

    2009-01-01

    The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

  3. Sub-millimeter wave frequency heterodyne detector system

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

    2010-01-01

    The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

  4. Intermediate Frequency Gravitational Wave Determination in the 10 micro-Hertz to 20 milli-Hertz Band Using Dense Pulsar Timing Campaigns

    NASA Astrophysics Data System (ADS)

    Dolch, Timothy; Lam, Michael; Ellis, Justin; Chatterjee, Shami; Cordes, James; Madison, Dustin; Chernoff, David; Nanograv Collaboration; Ipta Collaboration

    2015-04-01

    Dense, continuous pulsar timing observations over a 24-hr period provide a method for probing intermediate gravitational wave (GW) frequencies of 10 micro-Hertz to 20 milli-Hertz. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav), the Parkes Pulsar Timing Array, the European Pulsar Timing Array, and the entire International Pulsar Timing Array all use millisecond pulsar observations to constrain GWs typically at nano-Hz frequencies. In the case of the IPTA's nine-telescope 1713 24-Hour Global Campaign on millisecond pulsar J1713 + 0747 (Dolch et al. 2014), gravitational wave limits in the intermediate frequency regime can be produced. These limits overlap with limits from Cassini Doppler tracking. The negligible change in dispersion measure allows for a white noise model to be used with the timing residuals in order to constrain any contributions from GWs. We show the current status of GW limiting using the 1713 global data. We then discuss the relevant GW sources, and the advantages of using the 1713 global data to limit contributions from such sources. Future campaigns using simultaneous, continuous observations of multiple pulsars will also be discussed.

  5. Prediction of vibrational frequencies of possible intermediates and side products of the methanol synthesis on ZnO(0001) by ab initio calculations.

    PubMed

    Kossmann, Jörg; Rossmüller, Guido; Hättig, Christof

    2012-01-21

    We used ab initio density functional theory in combination with an embedded cluster approach to calculate vibrational spectra and formation enthalpies of possible intermediates and side products (spectator species) in the synthesis of methanol out of syngas on the ZnO(0001) surface. Our investigations are based upon our previous work on possible reaction pathways and activation barriers for this reaction at oxygen vacancies on ZnO(0001). We present and discuss calculated vibrational frequencies of short-living formyl, hydroxymethylene, formaldehyde, acetale, and hydroxymethyl intermediates and compare the calculated frequencies of formate and methoxy species as well as CO and CO(2) species, at the defect free surface and at oxygen vacancies, with recent experimental findings. All investigated species show characteristic features in their spectra. Therefore, the analysis of their vibrational frequencies is a suitable mean to distinguish them and gain new insights in this reaction which is of recent experimental interest. We are able to identify the structure and characteristics of different surface species, such as monodentate and polydentate carbonate and formate species, in agreement with experimental results. PMID:22280776

  6. Simulation of ground-water flow in the Intermediate and Floridan aquifer systems in Peninsular Florida

    USGS Publications Warehouse

    Sepulveda, Nicasio

    2002-01-01

    A numerical model of the intermediate and Floridan aquifer systems in peninsular Florida was used to (1) test and refine the conceptual understanding of the regional ground-water flow system; (2) develop a data base to support subregional ground-water flow modeling; and (3) evaluate effects of projected 2020 ground-water withdrawals on ground-water levels. The four-layer model was based on the computer code MODFLOW-96, developed by the U.S. Geological Survey. The top layer consists of specified-head cells simulating the surficial aquifer system as a source-sink layer. The second layer simulates the intermediate aquifer system in southwest Florida and the intermediate confining unit where it is present. The third and fourth layers simulate the Upper and Lower Floridan aquifers, respectively. Steady-state ground-water flow conditions were approximated for time-averaged hydrologic conditions from August 1993 through July 1994 (1993-94). This period was selected based on data from Upper Floridan a quifer wells equipped with continuous water-level recorders. The grid used for the ground-water flow model was uniform and composed of square 5,000-foot cells, with 210 columns and 300 rows.

  7. Robust Blind Frequency and Transition Time Estimation for Frequency Hopping Systems

    NASA Astrophysics Data System (ADS)

    Fu, Kuo-Ching; Chen, Yung-Fang

    2010-12-01

    In frequency hopping spread spectrum (FHSS) systems, two major problems are timing synchronization and frequency estimation. A blind estimation scheme is presented for estimating frequency and transition time without using reference signals. The scheme is robust in the sense that it can avoid the unbalanced sampling block problem that occurs in existing maximum likelihood-based schemes, which causes large errors in one of the estimates of frequency. The proposed scheme has a lower computational cost than the maximum likelihood-based greedy search method. The estimated parameters are also used for the subsequent time and frequency tracking. The simulation results demonstrate the efficacy of the proposed approach.

  8. a Pre-Emphasis Technique to Broaden the Usable Frequency Range in Swept-Frequency Systems

    NASA Astrophysics Data System (ADS)

    Gammell, Paul M.; Maruvada, Subha; Liu, Yunbo; Harris, Gerald R.

    2010-02-01

    The usable frequency range of an ultrasonic swept-frequency system can be compromised because of transducer bandwidth limitations or sample frequency response and corresponding signal-to-noise (S/N) considerations. By adding a variable gain amplifier together with an arbitrary waveform generator that is synchronized with the frequency sweep, the dynamic range of the receiver can be accommodated over a wider frequency range. This pre-emphasis approach has been demonstrated for two applications: substitution calibration of hydrophones and attenuation measurements.

  9. Utilization of polymer enclosed intermediate class arresters to improve the performance of modern power systems

    SciTech Connect

    Sakich, J.D.; Lenk, D.W. ); Koepfinger, J.L. )

    1992-07-01

    This paper introduces the first commercially available polymer enclosed intermediate class metal oxide surge arrester. It describes the unique construction of the design, including reduced size, increased flexibility, a collared seal on the polymer housing and an open webbed fiberglass-epoxy module which houses the metal oxide disc elements. Performance advantages are discussed. These include improved short term contamination performance of the insulator-like polymer design when compared to multi-unit porcelain housed designs. Data will show that polymer housed open-webbed fiberglass module construction extends the pressure relief capability beyond that of typical porcelain enclosed designs. The capability of the polymer enclosed design to withstand repeated pressure relief tests, simulating system reclose on a failed arrester, is also discussed. This paper discusses the circumstances at one utility which has considered utilizing polymer enclosed intermediate class arresters to effectively upgrade their system protection capabilities.

  10. Coherent Frequency Reference System for the NASA Deep Space Network

    NASA Technical Reports Server (NTRS)

    Tucker, Blake C.; Lauf, John E.; Hamell, Robert L.; Gonzaler, Jorge, Jr.; Diener, William A.; Tjoelker, Robert L.

    2010-01-01

    The NASA Deep Space Network (DSN) requires state-of-the-art frequency references that are derived and distributed from very stable atomic frequency standards. A new Frequency Reference System (FRS) and Frequency Reference Distribution System (FRD) have been developed, which together replace the previous Coherent Reference Generator System (CRG). The FRS and FRD each provide new capabilities that significantly improve operability and reliability. The FRS allows for selection and switching between frequency standards, a flywheel capability (to avoid interruptions when switching frequency standards), and a frequency synthesis system (to generate standardized 5-, 10-, and 100-MHz reference signals). The FRS is powered by redundant, specially filtered, and sustainable power systems and includes a monitor and control capability for station operations to interact and control the frequency-standard selection process. The FRD receives the standardized 5-, 10-, and 100-MHz reference signals and distributes signals to distribution amplifiers in a fan out fashion to dozens of DSN users that require the highly stable reference signals. The FRD is also powered by redundant, specially filtered, and sustainable power systems. The new DSN Frequency Distribution System, which consists of the FRS and FRD systems described here, is central to all operational activities of the NASA DSN. The frequency generation and distribution system provides ultra-stable, coherent, and very low phase-noise references at 5, l0, and 100 MHz to between 60 and 100 separate users at each Deep Space Communications Complex.

  11. Responses of an isolation system with distinct multiple frequencies

    SciTech Connect

    Wu, Ting-shu; Seidensticker, R.W.

    1991-01-01

    Base isolation systems are generally designed with a single natural frequency. A major concern for these isolation systems is that, if the dominant frequency of a future earthquake is equal or close to the system's natural frequency, the ground motion will be greatly amplified because of resonance,and the superstructure would suffer severe damages. This paper present an isolation system designed with two distinct frequencies. Its responses to different ground motions, including a harmonic motion, show that no excessive amplification will occur. Adoption of this isolation system would greatly enhance the safety of an isolated superstructure against future strong earthquakes. 3 refs., 4 figs., 2 tabs.

  12. The system design of a rubidium maser frequency standard

    NASA Technical Reports Server (NTRS)

    Xiong, C. X.

    1984-01-01

    The Rubidium Maser Frequency Standard is a precision frequency source with excellent short-term stability. A type PBR-II Rb maser frequency standard was developed by the Beijing Institute of Radio Metrology and Measurement (BIRMM). The time-domain frequency stability (two-sample variance) of this frequency standard is less than 1/5 times 10 to the 13th power for t=10ms yields 1.0s, fh=1.0 KHz. Two PBR-II frequency standards were used as reference frequency sources in a frequency stability measurement system. Some important system characteristics for the PBR-II Rb maser frequency standard such as phase noise and frequency stability transfer characteristics are discussed. Furthermore, the design of the frequency standard for optimum frequency stability of the output signal; the choice of a voltage controlled crystal oscillator for the frequency standard; the design of the phase-locked loop; and the frequency stability test results on the PBR-II are discussed.

  13. Ultra-wideband communication system prototype using orthogonal frequency coded SAW correlators.

    PubMed

    Gallagher, Daniel R; Kozlovski, Nikolai Y; Malocha, Donald C

    2013-03-01

    This paper presents preliminary ultra-wideband (UWB) communication system results utilizing orthogonal frequency coded SAW correlators. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for spread-spectrum UWB. The use of OFC spectrally spreads a PN sequence beyond that of CDMA; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach, but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are typically needed in the intermediate frequency (IF) section in the transmitter and receiver, and greatly reduces the signal processing requirements. Development and results of an experimental prototype system with center frequency of 250 MHz are presented. The prototype system is configured using modular RF components and benchtop pulse generator and frequency source. The SAW correlation filters used in the test setup were designed using 7 chip frequencies within the transducer. The fractional bandwidth of approximately 29% was implemented to exceed the defined UWB specification. Discussion of the filter design and results are presented and are compared with packaged device measurements. A prototype UWB system using OFC SAW correlators is demonstrated in wired and wireless configurations. OFC-coded SAW filters are used for generation of a transmitted spread-spectrum UWB and matched filter correlated reception. Autocorrelation and cross-correlation system outputs are compared. The results demonstrate the feasibility of UWB SAW correlators for use in UWB communication transceivers. PMID:23475929

  14. MCNP5 CRITICALITY VALIDATION AND BIAS FOR INTERMEDIATE ENRICHED URANIUM SYSTEMS

    SciTech Connect

    FINFROCK SH

    2009-12-10

    The purpose of this analysis is to validate the Monte Carlo N-Particle 5 (MCNP5) code Version 1.40 (LA-UR-03-1987, 2005) and its cross-section database for k-code calculations of intermediate enriched uranium systems on INTEL{reg_sign} processor based PC's running any version of the WINDOWS operating system. Configurations with intermediate enriched uranium were modeled with the moderator range of 39 {le} H/Fissile {le} 1438. See Table 2-1 for brief descriptions of selected cases and Table 3-1 for the range of applicability for this validation. A total of 167 input cases were evaluated including bare and reflected systems in a single body or arrays. The 167 cases were taken directly from the previous (Version 4C [Lan 2005]) validation database. Section 2.0 list data used to calculate k-effective (k{sub eff}) for the 167 experimental criticality benchmark cases using the MCNP5 code v1.40 and its cross section database. Appendix B lists the MCNP cross-section database entries validated for use in evaluating the intermediate enriched uranium systems for criticality safety. The dimensions and atom densities for the intermediate enriched uranium experiments were taken from NEA/NSC/DOC(95)03, September 2005, which will be referred to as the benchmark handbook throughout the report. For these input values, the experimental benchmark k{sub eff} is approximately 1.0. The MCNP validation computer runs ran to an accuracy of approximately {+-} 0.001. For the cases where the reported benchmark k{sub eff} was not equal to 1.0000 the MCNP calculational results were normalized. The difference between the MCNP validation computer runs and the experimentally measured k{sub eff} is the MCNP5 v1.40 bias. The USLSTATS code (ORNL 1998) was utilized to perform the statistical analysis and generate an acceptable maximum k{sub eff} limit for calculations of the intermediate enriched uranium type systems.

  15. Low-frequency radio navigation system

    NASA Technical Reports Server (NTRS)

    Wallis, D. E. (Inventor)

    1983-01-01

    A method of continuous wave navigation using four transmitters operating at sufficiently low frequencies to assure essentially pure groundwave operation is described. The transmitters are keyed to transmit constant bursts (1/4 sec) in a time-multiplexed pattern with phase modulation of at least one transmitter for identification of the transmitters and with the ability to identify the absolute phase of the modulated transmitter and the ability to modulate low rate data for transmission. The transmitters are optimally positioned to provide groundwave coverage over a service region of about 50 by 50 km for the frequencies selected in the range of 200 to 500 kHz, but their locations are not critical because of the beneficial effect of overdetermination of position of a receiver made possible by the fourth transmitter. Four frequencies are used, at least two of which are selected to provide optimal resolution. All transmitters are synchronized to an average phase as received by a monitor receiver.

  16. Limiting amplifier for instantaneous frequency measuring system

    NASA Astrophysics Data System (ADS)

    Askew, R. E.

    1984-12-01

    The microwave integrated-circuit limiting amplifier (LA) described in this article was designed to provide a constant output signal level over a wide (8 to 11 GHz) frequency band while the input signal level varies over the range of -50 to 0 dBm. A salient feature of the LA is the slope of the output power versus frequency response. This slope allows the LA to function as a wide-band limiter/discriminator when a suitable detector is added to the output.

  17. Allan deviation computations of a linear frequency synthesizer system using frequency domain techniques

    NASA Technical Reports Server (NTRS)

    Wu, Andy

    1995-01-01

    Allan Deviation computations of linear frequency synthesizer systems have been reported previously using real-time simulations. Even though it takes less time compared with the actual measurement, it is still very time consuming to compute the Allan Deviation for long sample times with the desired confidence level. Also noises, such as flicker phase noise and flicker frequency noise, can not be simulated precisely. The use of frequency domain techniques can overcome these drawbacks. In this paper the system error model of a fictitious linear frequency synthesizer is developed and its performance using a Cesium (Cs) atomic frequency standard (AFS) as a reference is evaluated using frequency domain techniques. For a linear timing system, the power spectral density at the system output can be computed with known system transfer functions and known power spectral densities from the input noise sources. The resulting power spectral density can then be used to compute the Allan Variance at the system output. Sensitivities of the Allan Variance at the system output to each of its independent input noises are obtained, and they are valuable for design trade-off and trouble-shooting.

  18. Tolerance of the frequency deviation of LO sources at a MIMO system

    NASA Astrophysics Data System (ADS)

    Xiao, Jiangnan; Li, Xingying; Zhang, Zirang; Xu, Yuming; Chen, Long; Yu, Jianjun

    2015-11-01

    We analyze and simulate the tolerance of frequency offset at a W-band optical-wireless transmission system. The transmission system adopts optical polarization division multiplexing (PDM), and multiple-input multiple-output (MIMO) reception. The transmission signal adopts optical quadrature phase shift keying (QPSK) modulation, and the generation of millimeter-wave is based on the optical heterodyning technique. After 20-km single-mode fiber-28 (SMF-28) transmission, tens of Gb/s millimeter-wave signal is delivered. At the receiver, two millimeter-wave signals are down-converted into electrical intermediate-frequency (IF) signals in the analog domain by mixing with two electrical local oscillators (LOs) with different frequencies. We investigate the different frequency LO effect on the 2×2 MIMO system performance for the first time, finding that the process during DSP of implementing frequency offset estimation (FOE) before cascaded multi-modulus-algorithm (CMMA) equalization can get rid of the inter-channel interference (ICI) and improve system bit-error-ratio (BER) performance in this type of transmission system.

  19. NSLS-II Radio Frequency Systems

    SciTech Connect

    Rose J.; Gao F.; Goel, A.; Holub, B.; Kulpin, J.; Marques, C.; Yeddulla, M.

    2015-05-03

    The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. The NSLS-II RF system consists of the master oscillator, digital low level RF controllers, linac, booster and storage ring RF sub-systems, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system.

  20. Frequency response characteristics of the fuzzy polar power system stabilizer

    SciTech Connect

    Ortmeyer, T.H.; Hiyama, Takashi

    1995-06-01

    The fuzzy polar power system stabilizer (FPPSS) which has been recently developed is analyzed using frequency domain methods. the frequency domain approach allows the PSS designer to compare the new FPPSS with more conventional controllers. The significance of the three FPPSS design parameters are readily seen from the frequency response data, and their relationship to the conventional lead-lag design approach can be evaluated. Furthermore, the frequency response data for the FPPSS allows an alternate design approach for this stabilizer, and can be used to develop information concerning the small signal stability of the resulting system.

  1. A New Model of Frequency Delay in Power Systems

    SciTech Connect

    Nutaro, James; Protopopescu, Vladimir

    2012-11-01

    Observations of slow frequency signals in power systems have been explained by continuum wave equations that approximate the system's electromechanical dynamics. These continuum models predict that the signal speed is a function of the rotational inertia of the generators and impedances of the transmission lines. Here, we show that frequency signals with speeds modulated by these factors are predicted by the swing and Kirchhoff equations, without resorting to a continuum model. Our analysis also shows that the precision of the sensors used to measure frequency has a significant impact on the apparent speed of the frequency signal.

  2. Frequency Control Concerns in the North American Electric Power System

    SciTech Connect

    Kirby, B.J.

    2003-03-26

    This paper examines the relationship between system frequency, reliability and markets. It was prompted by the frequency deviations recently experienced at 2200 hours daily but is more generally concerned with the question of what frequency control is necessary. The paper does not provide new information or document new research. Nor is it intended to educate readers concerning power system engineering. Instead, the purpose is to reexamine well known truths concerning the power system and to freshly explore the basic relationship between frequency, reliability and markets: stepping back, if you will, to see if we are collectively missing something. The concern of this paper is with frequency and reliability. Off-nominal frequency can impact reliability and markets efficiency (as we are using the term here) in four ways. It could damage equipment (generation, transmission, or load). It could degrade the quality of the product being delivered to end users (too low and lights would flicker unacceptably, for example). It could result in the collapse of the power system itself (by triggering protective system actions, for example). Or it could result in overloading transmission lines as various generators try to restore system frequency impacting markets efficiency. Often these causes operate in concert. Generator protective systems take action to prevent generator damage, for example, but exacerbate the overall generation/load imbalance. The paper is divided into two sections. The Introduction is followed by a section titled ''A Perspective on Frequency Control'' which addresses the physical requirements of the power system and how market transactions interact with the physical system. The ''Frequency Standards and Control Performance'' section discusses the various NERC and regional reliability council policies that govern utility performance and how these relate to frequency and reliability. Finally, Conclusions are provided.

  3. The Role of Time and Frequency in Future Systems

    NASA Technical Reports Server (NTRS)

    Stein, Samuel R.; Gifford, Al; Celano, Tom

    1996-01-01

    Over the past twenty years, the Global Positioning System (GPS) has revolutionized the performance and the geographical availability of time and frequency discrimination, while at the same time reducing the cost to the individual user. This paper examines the question of what comes next for time and frequency dissemination. The question has two motivations: How can improved performance be achieved in the future, and how can redundant sources of time and frequency be provided to critical systems? A model is developed for time and frequency dissemination based on the time management performed in GPS. Several candidate systems for future time and frequency distribution are identified. One system - SONET telecommunications - is discussed in detail. Performance requirements and hardware implementation are presented.

  4. Frequency domain system identification methods - Matrix fraction description approach

    NASA Technical Reports Server (NTRS)

    Horta, Luca G.; Juang, Jer-Nan

    1993-01-01

    This paper presents the use of matrix fraction descriptions for least-squares curve fitting of the frequency spectra to compute two matrix polynomials. The matrix polynomials are intermediate step to obtain a linearized representation of the experimental transfer function. Two approaches are presented: first, the matrix polynomials are identified using an estimated transfer function; second, the matrix polynomials are identified directly from the cross/auto spectra of the input and output signals. A set of Markov parameters are computed from the polynomials and subsequently realization theory is used to recover a minimum order state space model. Unevenly spaced frequency response functions may be used. Results from a simple numerical example and an experiment are discussed to highlight some of the important aspect of the algorithm.

  5. The Earth's entropy production budget as simulated by a climate system model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Kleidon, A.; Fraedrich, K.; Lunkeit, F.; Jansen, H.

    2003-04-01

    The Earth is an open thermodynamic system far from equilibrium. It has been suggested that processes within such systems evolve to states of maximum entropy production. Here we report on the entropy production budget of the climate system as simulated by the intermediate complexity climate model PUMA, which consists of an atmospheric general circulation model of coarse resolution, a land surface representation, and a mixed-layer ocean model. We expanded the model to explicitly calculate entopy production for absorption of solar and terrestrial radiation, turbulent fluxes of sensible and latent heat, atmospheric and oceanic heat transport, and entropy production associated with biotic productivity. We present the general methodology, the entropy production budget for the present-day climatic mean, and the sensitivity to vegetation related land surface characteristics.

  6. Radio Sources Associated with Intermediate X-ray Luminosity Objects in Merging Galaxy Systems

    NASA Technical Reports Server (NTRS)

    Neff, S. G.; Ulvestad, J. S.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    We present new, high-resolution 6, 3.6, and 2 cm radio images of a time-ordered sequence of merging galaxy systems. The new data have a resolution of less than 100pc and a sensitivity comparable to a few x Cas A. We detect compact radio sources in all systems, generally embedded in more diffuse radio emission at the longer wavelengths. Several of the compact radio sources are coincident with compact Intermediate-luminosity X-ray Objects (IXOs) in these systems, and many more are within the 3$/sigma$ Chandra position errors for other IXOs. The fraction of radio identifications and the nature of the radio sources changes as a function of merger stage. These data suggest that the IXOs are associated with complexes of supernova remnants, and therefore with star formation that has occurred within the last $/sim$10$circumflex7$ yr, but are not located in HII regions where copious star formation is occurring currently.

  7. Planck intermediate results. XVII. Emission of dust in the diffuse interstellar medium from the far-infrared to microwave frequencies

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Abergel, A.; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Aniano, G.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bonaldi, A.; Bond, J. R.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Joncas, G.; Jones, A.; Jones, W. C.; Juvela, M.; Kalberla, P.; Keihänen, E.; Kerp, J.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Spencer, L. D.; Starck, J.-L.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Verstraete, L.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Winkel, B.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-06-01

    The dust-Hi correlation is used to characterize the emission properties of dust in the diffuse interstellar medium (ISM) from far infrared wavelengths to microwave frequencies. The field of this investigation encompasses the part of the southern sky best suited to study the cosmic infrared and microwave backgrounds. We cross-correlate sky maps from Planck, the Wilkinson Microwave Anisotropy Probe (WMAP), and the diffuse infrared background experiment (DIRBE), at 17 frequencies from 23 to 3000 GHz, with the Parkes survey of the 21 cm line emission of neutral atomic hydrogen, over a contiguous area of 7500 deg2 centred on the southern Galactic pole. We present a general methodology to study the dust-Hi correlation over the sky, including simulations to quantify uncertainties. Our analysis yields four specific results. (1) We map the temperature, submillimetre emissivity, and opacity of the dust per H-atom. The dust temperature is observed to be anti-correlated with the dust emissivity and opacity. We interpret this result as evidence of dust evolution within the diffuse ISM. The mean dust opacity is measured to be (7.1 ± 0.6) × 10-27 cm2 H-1 × (ν/ 353 GHz)1.53 ± 0.03 for 100 ≤ ν ≤ 353 GHz. This is a reference value to estimate hydrogen column densities from dust emission at submillimetre and millimetre wavelengths. (2) We map the spectral index βmm of dust emission at millimetre wavelengths (defined here as ν ≤ 353 GHz), and find it to be remarkably constant at βmm = 1.51 ± 0.13. We compare it with the far infrared spectral index βFIR derived from greybody fits at higher frequencies, and find a systematic difference, βmm - βFIR = - 0.15, which suggests that the dust spectral energy distribution (SED) flattens at ν ≤ 353 GHz. (3) We present spectral fits of the microwave emission correlated with Hi from 23 to 353 GHz, which separate dust and anomalous microwave emission (AME). We show that the flattening of the dust SED can be accounted for with

  8. High frequency analysis of a plate carrying a concentrated nonlinear spring-mass system

    NASA Astrophysics Data System (ADS)

    Culver, Dean; Dowell, Earl

    2016-09-01

    Examining the behavior of dynamical systems with many degrees of freedom undergoing random excitation at high frequency often requires substantial computation. These requirements are even more stringent for nonlinear systems. One approach for describing linear systems, Asymptotic Modal Analysis (AMA), has been extended to nonlinear systems in this paper. A prototypical system, namely a thin plate carrying a concentrated hardening cubic spring-mass, is explored. The study focuses on the response of three principal variables to random, frequency-bounded excitation: the displacement of the mounting location of the discrete spring-mass, the relative displacement of the discrete mass to this mounting location, and the absolute displacement of the discrete mass. The results indicate that extending AMA to nonlinear systems for input frequency bands containing a large number of modes is feasible. Several advantageous properties of nonlinear AMA are found, and an additional reduced frequency-domain modal method, Dominance-Reduced Classical Modal Analysis (DRCMA), is proposed that is intermediate in accuracy and the cost of computation between AMA and Classical Modal Analysis (CMA).

  9. Beat frequency ultrasonic microsphere contrast agent detection system

    NASA Technical Reports Server (NTRS)

    Pretlow, III, Robert A. (Inventor); Yost, William T. (Inventor); Cantrell, Jr., John H. (Inventor)

    1997-01-01

    A system for and method of detecting and measuring concentrations of an ultrasonically-reflective microsphere contrast agent involving detecting non-linear sum and difference beat frequencies produced by the microspheres when two impinging signals with non-identical frequencies are combined by mixing. These beat frequencies can be used for a variety of applications such as detecting the presence of and measuring the flow rates of biological fluids and industrial liquids, including determining the concentration level of microspheres in the myocardium.

  10. Progress on radio frequency auxiliary heating system designs in ITER

    SciTech Connect

    Makowski, M.; Bosia, G.; Elio, F.

    1996-09-01

    ITER will require over 100 MW of auxiliary power for heating, on- and off-axis current drive, accessing the H-mode, and plasma shut-down. The Electron Cyclotron Range of Frequencies (ECRF) and Ion Cyclotron Range of Frequencies (ICRF) are two forms of Radio Frequency (RF) auxiliary power being developed for these applications. Design concepts for both the ECRF and ICRF systems are presented, key features and critical design issues are discussed, and projected performances outlined.

  11. Development of optical fiber frequency and time distribution systems

    NASA Technical Reports Server (NTRS)

    Lutes, G.

    1982-01-01

    The development of ultra stable optical fiber distribution systems for the dissemination of frequency and timing references is reported. The ultimate design goals for these systems are a frequency stability of 10 to the -17 power for tau or = 100 sec and time stability of + or - 0.1 ns for 1 year and operation over distances or = 30 km. A prototype system is reviewed and progress is discussed.

  12. A Simple Joint Estimation Method of Residual Frequency Offset and Sampling Frequency Offset for DVB Systems

    NASA Astrophysics Data System (ADS)

    Kwon, Ki-Won; Cho, Yongsoo

    This letter presents a simple joint estimation method for residual frequency offset (RFO) and sampling frequency offset (STO) in OFDM-based digital video broadcasting (DVB) systems. The proposed method selects a continual pilot (CP) subset from an unsymmetrically and non-uniformly distributed CP set to obtain an unbiased estimator. Simulation results show that the proposed method using a properly selected CP subset is unbiased and performs robustly.

  13. Dynamic analysis of parametrically excited system under uncertainties and multi-frequency excitations

    NASA Astrophysics Data System (ADS)

    Wei, Sha; Han, Qinkai; Peng, Zhike; Chu, Fulei

    2016-05-01

    Some system parameters in mechanical systems are always uncertain due to uncertainties in geometric and material properties, lubrication condition and wear. For a more reasonable estimation of dynamic analysis of the parametrically excited system, the effect of uncertain parameters should be taken into account. This paper presents a new non-probabilistic analysis method for solving the dynamic responses of parametrically excited systems under uncertainties and multi-frequency excitations. By using the multi-dimensional harmonic balance method (MHBM) and the Chebyshev inclusion function (CIF), an interval multi-dimensional harmonic balance method (IMHBM) is obtained. To illustrate the accuracy of the proposed method, a time-varying geared system of wind turbine with different kinds of uncertainties is demonstrated. By comparing with the results of the scanning method, it is shown that the presented method is valid and effective for the parametrically excited system with uncertainties and multi-frequency excitations. The effects of some uncertain system parameters including uncertain mesh stiffnesses and uncertain bearing stiffnesses on the frequency responses of the system are also discussed in detail. It is shown that the dynamic responses of the system are insensitive to the uncertain mesh stiffness and bearing stiffnesses of the planetary gear stage. The uncertain bearing stiffnesses of the intermediate and high-speed stages will lead to relatively large uncertainties in the dynamic responses around resonant regions. It will provide valuable guidance for the optimal design and condition monitoring of wind turbine gearboxes.

  14. Hydrogeologic framework and geochemistry of the intermediate aquifer system in parts of Charlotte, De Soto, and Sarasota counties, Florida

    USGS Publications Warehouse

    Torres, A.E.; Sacks, L.A.; Yobbi, D.K.; Knochenmus, L.A.; Katz, B.G.

    2001-01-01

    The hydrogeologic framework underlying the 600-square-mile study area in Charlotte, De Soto, and Sarasota Counties, Florida, consists of the surficial aquifer system, the intermediate aquifer system, and the Upper Floridan aquifer. The hydrogeologic framework and the geochemical processes controlling ground-water composition were evaluated for the study area. Particular emphasis was given to the analysis of hydrogeologic and geochemical data for the intermediate aquifer system. Flow regimes are not well understood in the intermediate aquifer system; therefore, hydrogeologic and geochemical information were used to evaluate connections between permeable zones within the intermediate aquifer system and between overlying and underlying aquifer systems. Knowledge of these connections will ultimately help to protect ground-water quality in the intermediate aquifer system. The hydrogeology was interpreted from lithologic and geophysical logs, water levels, hydraulic properties, and water quality from six separate well sites. Water-quality samples were collected from wells located along six ground-water flow paths and finished at different depth intervals. The selection of flow paths was based on current potentiometric-surface maps. Ground-water samples were analyzed for major ions; field parameters (temperature, pH, specific conductance, and alkalinity); stable isotopes (deuterium, oxygen-18, and carbon-13); and radioactive isotopes (tritium and carbon-14). The surficial aquifer system is the uppermost aquifer, is unconfined, relatively thin, and consists of unconsolidated sand, shell, and limestone. The intermediate aquifer system underlies the surficial aquifer system and is composed of clastic sediments interbedded with carbonate rocks. The intermediate aquifer system is divided into three permeable zones, the Tamiami/Peace River zone (PZ1), the Upper Arcadia zone (PZ2), and the Lower Arcadia zone (PZ3). The Tamiami/Peace River zone (PZ1) is the uppermost zone and is

  15. Evidence for a New Intermediate Phase in a Strongly Correlated 2D System near Wigner Crystallization

    NASA Astrophysics Data System (ADS)

    Gao, Xuan; Qiu, Richard; Goble, Nicholas; Serafin, Alex; Yin, Liang; Xia, Jian-Sheng; Sullivan, Neil; Pfeiffer, Loren; West, Ken

    How the two dimensional (2D) quantum Wigner crystal (WC) transforms into the metallic liquid phase remains an outstanding problem in physics. In theories considering the 2D WC to liquid transition in the clean limit, it was suggested that a number of intermediate phases might exist. We have studied the transformation between the metallic fluid phase and the low magnetic field reentrant insulating phase (RIP) which was interpreted as due to the WC [Qiu et al., PRL 108, 106404 (2012)], in a strongly correlated 2D hole system in GaAs quantum well with large interaction parameter rs (~20-30) and high mobility. Instead of a sharp transition, we found that increasing density (or lowering rs) drives the RIP into a state where the incipient RIP coexists with Fermi liquid. This apparent mixture phase intermediate between Fermi liquid and WC also exhibits a non-trivial temperature dependent resistivity behavior which can be qualitatively understood by the reversed melting of WC in the mixture, in analogy to the Pomeranchuk effect in the solid-liquid mixture of Helium-3. X.G. thanks NSF (DMR-0906415) for supporting work at CWRU. Experiments at the NHMFL High B/T Facility were supported by NSF Grant 0654118 and the State of Florida. L.P. thanks the Gordon and Betty Moore Foundation and NSF MRSEC (DMR-0819860) for support.

  16. Study on an Efficient Dehumidifying Air-conditioning System utilizing Phase Change of Intermediate Pressure Refrigerant

    NASA Astrophysics Data System (ADS)

    Maeda, Kensaku; Inaba, Hideo

    The present study has proven a new dehumidifying system that aimed to reduce the sensible heat factor(SHF) of cooling process without using additional heat to relieve the internationally indicated conflict between energy saving and dehumidification necessary for keeping adequate indoor air quality (IAQ). In this system, we used intermediate pressure refrigerant in a vapor compression refrigerating cycle as heat transfer medium of a characteristic heat exchanger to precool the process air entering into an evaporator as well as to reheat the process air leaving from the evaporator. By this system, the present results achieved higher moisture removal and consequently higher efficiency of dehumidifying process. In addition to this fact, since this system has capability of integration into air-conditioning apparatus(HVAC system), it will be able to work for wide range of cooling load by variable SHF function. In the present paper, technical information, experimental results, and simulation results which assumed to apply this system into HVAC system are reported.

  17. 7. Survivable low frequency communication system pathway, looking east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Survivable low frequency communication system pathway, looking east - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  18. Controlled oscillator system with a time dependent output frequency

    NASA Technical Reports Server (NTRS)

    Winkelstein, R. A. (Inventor)

    1973-01-01

    A controlled oscillator system is presented for providing an output with a frequency which changes with respect to time and with a phase which is within established phase error limits. The system includes a frequency synthesizer with a symmetrical search oscillator, capable of tuning the output with a range of + or - 100 Hz about any fixed frequency to which the synthesizer is set. For a tuning range of 200 Hz (+ or - 100 Hz) an expanded search oscillator output of a frequency range of 4 MHz (from 1 MHz to 5 MHz) is provided. A counter counts continuously the expanded output cycles and at each of fixed sampling intervals, for every 0.1 second, the count or number accumulated in the counter is read out. The sample number is compared with a theoretical number which should be present in the counter at the particular sampling instant for proper synthesizer's output frequency and phase.

  19. Composite cathode materials development for intermediate temperature solid oxide fuel cell systems

    NASA Astrophysics Data System (ADS)

    Qin, Ya

    Solid oxide fuel cell (SOFC) systems are of particular interest as electrochemical power systems that can operate on various hydrocarbon fuels with high fuel-to-electrical energy conversion efficiency. Within the SOFC stack, La0.8Sr 0.2Ga0.8Mg0.115Co0.085O3-delta (LSGMC) has been reported as an optimized composition of lanthanum gallate based electrolytes to achieve higher oxygen ionic conductivity at intermediate temperatures, i.e., 500-700°C. The electrocatalytic properties of interfaces between LSGMC electrolytes and various candidate intermediate-temperature SOFC cathodes have been investigated. Sm0.5Sr0.5CoO 3-delta (SSC), and La0.6Sr0.4Co0.2Fe 0.8O3-delta (LSCF), in both pure and composite forms with LSGMC, were investigated with regards to both oxygen reduction and evolution, A range of composite cathode compositions, having ratios of SSC (in wt.%) with LSGMC (wt.%) spanning the compositions 9:1, 8:2, 7:3, 6:4 and 5:5, were investigated to determine the optimal cathode-electrolyte interface performance at intermediate temperatures. All LSGMC electrolyte and cathode powders were synthesized using the glycine-nitrate process (GNP). Symmetrical electrochemical cells were investigated with three-electrode linear dc polarization and ac impedance spectroscopy to characterize the kinetics of the interfacial reactions in detail. Composite cathodes were found to perform better than the single phase cathodes due to significantly reduced polarization resistances. Among those composite SSC-LSGMC cathodes, the 7:3 composition has demonstrated the highest current density at the equivalent overpotential values, indicating that 7:3 is an optimal mixing ratio of the composite cathode materials to achieve the best performance. For the composite SC-LSGMC cathode/LSGMC interface, the cathodic overpotential under 1 A/cm2 current density was as low as 0.085 V at 700°C, 0.062V at 750°C and 0.051V at 800°C in air. Composite LSCF-LSGMC cathode/LSGMC interfaces were found to have

  20. Advanced high frequency partial discharge measuring system

    NASA Technical Reports Server (NTRS)

    Karady, George G.

    1994-01-01

    This report explains the Advanced Partial Discharge Measuring System in ASU's High Voltage Laboratory and presents some of the results obtained using the setup. While in operation an insulation is subjected to wide ranging temperature and voltage stresses. Hence, it is necessary to study the effect of temperature on the behavior of partial discharges in an insulation. The setup described in this report can be used to test samples at temperatures ranging from -50 C to 200 C. The aim of conducting the tests described herein is to be able to predict the behavior of an insulation under different operating conditions in addition to being able to predict the possibility of failure.

  1. Intermediate-scale high-solids anaerobic digestion system operational development

    SciTech Connect

    Rivard, C.J.

    1995-02-01

    Anaerobic bioconversion of solid organic wastes represents a disposal option in which two useful products may be produced, including a medium Btu fuel gas (biogas) and a compost-quality organic residue. The application of high-solids technology may offer several advantages over conventional low-solids digester technology. Operation of the anaerobic digestion process at high solids reduces the level of process water and thereby the size and capital costs for the digester system. In addition, by virtue of the lack of available water, the microbial catalysts are more productive in feedstock polymer hydrolysis. The National Renewable Energy Laboratory (NREL) has developed a unique digester system capable of uniformly mixing high-solids materials at low cost. Information gained from laboratory-scale digester research was used to develop die intermediate-scale digester system. This system represents a 50-fold scale-up of the original digester system and includes continuous feed addition and computer monitoring and control. During the first 1.15 years of operation, a variety of modifications and improvements were instituted to increase the safety, reliability, and performance of the system. Those improvements -- which may be critical in further scale-up efforts using the NREL high-solids digester design -- are detailed in this report.

  2. Frequency content selection for dynamic analysis of marine systems

    SciTech Connect

    Garrett, D.L.; Gu, G.Z.; Watters, A.J.

    1995-12-31

    A recommended discretization of a wave spectrum for numerical analysis of the structural response of compliant marine systems is presented. Error estimates for the variance of structural response are presented as a function of system damping and spacing of frequencies in the discrete wave spectrum. Application of the recommended frequency spacing to calculation of the tendon tension response of a Tension Leg Platform, with particular attention to resonant pitch response, is presented. The applicability of the recommended discretization to time domain simulation is discussed and recommended frequency spacings and simulation lengths are presented.

  3. Alternatives generation and analysis for the Phase I intermediate waste feed staging system design requirements

    SciTech Connect

    Claghorn, R.D., Fluor Daniel Hanford

    1997-02-06

    This alternatives generation and analysis (AGA) addresses the question: What is the design basis for the facilities required to stage low-level waste (LLW) feed to the Phase I private contractors? Alternative designs for the intermediate waste feed staging system were developed, analyzed, and compared. Based on these analyses, this document recommends installing mixer pumps in the central pump pit of double-shell tanks 241-AP-102 and 241-AP-104. Also recommended is installing decant/transfer pumps at these tanks. These recommendations have clear advantages in that they provide a low shedule impact/risk and the highest operability of all the alternatives investigated. This revision incorporates comments from the decision board.

  4. Fission dynamics of intermediate-fissility systems: A study within a stochastic three-dimensional approach

    NASA Astrophysics Data System (ADS)

    Vardaci, E.; Nadtochy, P. N.; Di Nitto, A.; Brondi, A.; La Rana, G.; Moro, R.; Rath, P. K.; Ashaduzzaman, M.; Kozulin, E. M.; Knyazheva, G. N.; Itkis, I. M.; Cinausero, M.; Prete, G.; Fabris, D.; Montagnoli, G.; Gelli, N.

    2015-09-01

    The system of intermediate fissility 132Ce has been studied experimentally and theoretically to investigate the dissipation properties of nuclear matter. Cross sections of fusion-fission and evaporation-residue channels together with light charged particle multiplicities in both channels, their spectra, light charged particle-evaporation residue angular correlations, and mass-energy distribution of fission fragments have been measured. Theoretical analysis has been performed using a multidimensional stochastic approach coupled with a Hauser-Feshbach treatment of particle evaporation. The main conclusions are that the full one-body shape-dependent dissipation mechanism allows the reproduction of the full set of experimental data and that after a time τd=5 ×10-21 s from the equilibrium configuration of the compound nucleus, fission decay can occur in a time that can span several orders of magnitude.

  5. Custom Turnkey Time and Frequency Systems: A structured, expandable approach

    NASA Technical Reports Server (NTRS)

    Wright, David F.

    1995-01-01

    Radiocode Clocks Ltd. have developed a Turnkey Time and Frequency Generation and Distribution, System strategy based upon a bus of three, 'core' signals from which any Time code, Pulse rate or Frequency can be produced. The heart of the system is a ruggedized 19 inch, 3U Single Eurocard chassis constructed from machined 10mm aluminum alloy plate and designed to meet stringent Military, Security and Telecommunications specifications. The chassis is fitted with an advanced multilayer backplane with separate ground planes for analog and digital signals ensuring no degradation of low noise frequency references in the proximity of high speed digital pulse transmissions. The system has been designed to be used in three possible configurations: 1) As a stand alone generation and distribution instrument; 2) As a primary distribution unit in a turnkey Time and Frequency system; and 3) As a secondary distribution unit at a remote location from the Turnkey Time and Frequency System providing regeneration of core signals and correction for transmission delays. When configured as a secondary distribution unit the system will continue to provide usable outputs when one, two or even all three of the 'core' signals are lost. The instrument's placement within a system as a possible single point of system failure has required the development of very high reliability translator, synthesizer, phase locked loop and distribution modules together with a comprehensive alarm and monitoring strategy.

  6. Seismic visibility of a deep subduction channel - insights from numerical simulation of high-frequency seismic waves emitted from intermediate depth earthquakes

    NASA Astrophysics Data System (ADS)

    Friederich, W.; Lambrecht, L.; Stöckhert, B.; Wassmann, S.; Moos, C.

    2014-03-01

    Return flow in a deep subduction channel (DSC) has been proposed to explain rapid exhumation of high pressure-low temperature metamorphic rocks, entirely based on the fossil rock record. Supported by thermo-mechanical models, the DSC is envisioned as a thin layer on top of the subducted plate reaching down to minimum depths of about 150 km. We perform numerical simulations of high-frequency seismic wave propagation (1-5 Hz) to explore potential seismological evidence for the in situ existence of a DSC. Motivated by field observations, for modeling purposes we assume a simple block-in-matrix (BIM) structure with eclogitic blocks floating in a serpentinite matrix. Homogenization calculations for BIM structures demonstrate that effective seismic velocities in such composites are lower than in the surrounding oceanic crust and mantle, with nearly constant values along the entire length of the DSC. Synthetic seismograms for receivers at the surface computed for intermediate depth earthquakes in the subducted oceanic crust for models with and without DSC turn out to be markedly influenced by its presence or absence. While for both models P and S waveforms are dominated by delayed high-amplitude guided waves, models with DSC exhibit a very different pattern of seismic arrivals compared to models without DSC. The main reason for the difference is the greater length and width of the low-velocity channel when a DSC is present. Seismic velocity heterogeneity within the DSC or oceanic crust is of minor importance. The characteristic patterns allow for definition of typical signatures by which models with and without DSC may be discriminated. The signatures stably recur in slightly modified form for earthquakes at different depths inside subducted oceanic crust. Available seismological data from intermediate depth earthquakes recorded in the forearc of the Hellenic subduction zone exhibit similar multi-arrival waveforms as observed in the synthetic seismograms for models with

  7. Non-stationary frequency domain system identification using time-frequency representations

    NASA Astrophysics Data System (ADS)

    Guo, Yanlin; Kareem, Ahsan

    2016-05-01

    System properties of buildings and bridges may vary with time due to temperature changes, aging or extreme loadings. To identify these time-varying system properties, this study proposes a new output-only non-stationary system identification (SI) framework based on instantaneous or marginal spectra derived from the time-frequency representation, e.g., short time Fourier or wavelet transform. Spectra derived from these time-frequency representations are very popular in tracking time-varying frequencies; however, they have seldom been used to identify the time-varying damping ratio because a short window needed to capture the time-varying information amplifies the bandwidth significantly, which may lead to considerably overestimating the damping ratio. To overcome this shortcoming, this study modifies the theoretical frequency response function (FRF) to explicitly account for the windowing effect, and therefore enables SI directly using instantaneous or marginal spectra derived from the wavelet or short time Fourier transform. The response spectrum estimated using the short time window and the modified FRF are both influenced by the same time window, thus the instantaneous or time-localized marginal spectrum of response can be fitted to the modified FRF to identify frequency and damping ratio at each time instant. This spectral-based SI framework can reliably identify damping in time-varying systems under non-stationary excitations. The efficacy of the proposed framework is demonstrated by both numerical and full-scale examples, and also compared to the time-domain SI method, stochastic subspace identification (SSI), since the time-domain SI approaches and their extensions are popular in identifying time-varying systems utilizing recursive algorithms or moving windows.

  8. Switch over to the high frequency rf systems near transition

    SciTech Connect

    Brennan, J.M.; Wei, J.

    1988-01-01

    The purpose of this note is to point out that since bunch narrowing naturally occurs in the acceleration process in the vicinity of transition, it should be possible to switch over to the high frequency system close to transition when the bunch has narrowed enough to fit directly into the high frequency bucket. The advantage of this approach is the simplicity, no extra components or gymnastics are required of the low frequency system. The disadvantage, of course, is for protons which do not go through transition. But on the other hand, there is no shortage of intensity for protons and so it should be possible to keep the phase space area low for protons, and then matching to the high frequency bucket should be easily accomplished by adiabatic compression. 3 refs., 7 figs.

  9. Distributed Frequency Control of Prosumer-Based Electric Energy Systems

    SciTech Connect

    Nazari, MH; Costello, Z; Feizollahi, MJ; Grijalva, S; Egerstedt, M

    2014-11-01

    In this paper, we propose a distributed frequency regulation framework for prosumer-based electric energy systems, where a prosumer (producer-consumer) is defined as an intelligent agentwhich can produce, consume, and/or store electricity. Despite the frequency regulators being distributed, stability can be ensured while avoiding inter-area oscillations using a limited control effort. To achieve this, a fully distributed one-step model-predictive control protocol is proposed and analyzed, whereby each prosumer communicates solely with its neighbors in the network. The efficacy of the proposed frequency regulation framework is shown through simulations on two real-world electric energy systems of different scale and complexity. We show that prosumers can indeed bring frequency and power deviations to their desired values after small perturbations.

  10. Status of frequency and time support for NASA systems

    NASA Technical Reports Server (NTRS)

    Kuhnle, Paul F.; Kushmeider, Paul J.; Wardrip, S. Clark

    1994-01-01

    NASA has frequency and timing systems at many facilities and centers. Timing systems with specifications tighter than several microseconds are covered. These ground based systems support scientific experiments and spacecraft tracking for the following programs; NASA Satellite Laser Ranging (NSLR); Network Mission Operations Support (NMOS); Kennedy Space Center (KSC); Very Long Baseline Interferometry (VLBI); Tracking Data Relay Satellite System (TDRSS) Ground Terminal Network; and the Deep Space Network (DSN). Major equipment assemblies, specifications, performance, and requirements, both present and future, are presented.

  11. Autonomous Frequency-Domain System-Identification Program

    NASA Technical Reports Server (NTRS)

    Yam, Yeung; Mettler, Edward; Bayard, David S.; Hadaegh, Fred Y.; Milman, Mark H.; Scheid, Robert E.

    1993-01-01

    Autonomous Frequency Domain Identification (AU-FREDI) computer program implements system of methods, algorithms, and software developed for identification of parameters of mathematical models of dynamics of flexible structures and characterization, by use of system transfer functions, of such models, dynamics, and structures regarded as systems. Software considered collection of routines modified and reassembled to suit system-identification and control experiments on large flexible structures.

  12. Multi-frequency EIT hardware system based on DSP.

    PubMed

    Zhang, Shuai; Xu, Guizhi; Wu, Huanli; Geng, Duyan; Yan, Weili

    2006-01-01

    Electrical impedance tomography (EIT) is a new functional imaging technique in the biomedical engineering. A multi-frequency hardware EIT system based on digital signal processor (DSP) has been developed, and the system also has been designed using modular structure. Some experiments in vitro tissue are done and their images are generated with the filtered back-projection algorithm using this system in real time. The results show that this system is feasible, stable, convenient and extended. PMID:17959484

  13. Phase equilibrium and intermediate phases in the Eu-Sb system

    SciTech Connect

    Abdusalyamova, M.N.

    2011-10-15

    Rapid heating rate thermal analysis, X-ray diffraction, fluorescence spectrometry, and differential dissolution method were used to study the high-temperature phase equilibrium in the Eu-Sb system within the composition range between 37 and 96 at% Sb. The techniques were effective in determination of the vapor-solid-liquid equilibrium since intermediate phases except Eu{sub 4}Sb{sub 3} evaporated incongruently after melting. A thermal procedure was developed to determine the liquidus and solidus lines of the T-x diagram. Six stable phases were identified: two phases, EuSb{sub 2} and Eu{sub 4}Sb{sub 3}, melt congruently at 1045{+-}10 deg. C and 1600{+-}15 deg. C, the Eu{sub 2}Sb{sub 3}, Eu{sub 11}Sb{sub 10}, Eu{sub 5}Sb{sub 4}, and Eu{sub 5}Sb{sub 3} phases melt incongruently at 850{+-}8 deg. C, 950{+-}10 deg. C, 1350{+-}15 deg. C, and 1445{+-}15 deg. C, respectively. The exact composition shifting of Sb-rich decomposable phases towards Eu{sub 4}Sb{sub 3}, the most refractory compound, was determined. The topology of the Eu-Sb phase diagram was considered together with that of the Yb-Sb system. - Graphical abstract: The high-temperature range of the T-x phase diagram for the Eu-Sb system. Highlights: > The phase relations in the Eu-Sb system were studied over a large composition and temperature scale. > The liquidus and solidus lines of the T-x diagram were well established using effective techniques. > In the system, six binary phases are stable and they melt incongruently except EuSb{sub 2} and Eu{sub 4}Sb{sub 3}. > Incongruent evaporation was found to be typical of all the phases besides Eu{sub 4}Sb{sub 3}.

  14. Time-domain control of ultrahigh-frequency nanomechanical systems.

    PubMed

    Liu, N; Giesen, F; Belov, M; Losby, J; Moroz, J; Fraser, A E; McKinnon, G; Clement, T J; Sauer, V; Hiebert, W K; Freeman, M R

    2008-12-01

    Nanoelectromechanical systems could have applications in fields as diverse as ultrasensitive mass detection and mechanical computation, and can also be used to explore fundamental phenomena such as quantized heat conductance and quantum-limited displacement. Most nanomechanical studies to date have been performed in the frequency domain. However, applications in computation and information storage will require transient excitation and high-speed time-domain operation of nanomechanical systems. Here we show a time-resolved optical approach to the transduction of ultrahigh-frequency nanoelectromechanical systems, and demonstrate that coherent control of nanomechanical oscillation is possible through appropriate pulse programming. A series of cantilevers with resonant frequencies ranging from less than 10 MHz to over 1 GHz are characterized using the same pulse parameters. PMID:19057589

  15. Instantaneous high-resolution multiple-frequency measurement system based on frequency-to-time mapping technique.

    PubMed

    Nguyen, Tuan A; Chan, Erwin H W; Minasian, Robert A

    2014-04-15

    A new microwave photonic instantaneous frequency measurement system that can simultaneously measure multiple-frequency signals while achieving very high resolution and wide frequency measurement range is presented. It is based on the frequency-to-time mapping technique implemented using a frequency shifting recirculating delay line loop and a narrowband optical filter realized by the in-fiber stimulated Brillouin scattering effect. Experimental results demonstrate the realization of a multiple-frequency measurement capability over a frequency range of 0.1-20 GHz that can be extended to 90 GHz, and with a measurement resolution of 250 MHz. PMID:24979008

  16. Intermediate-dominated controllable biomimetic synthesis of gold nanoparticles in a quasi-biological system

    NASA Astrophysics Data System (ADS)

    Cui, Ran; Zhang, Ming-Xi; Tian, Zhi-Quan; Zhang, Zhi-Ling; Pang, Dai-Wen

    2010-10-01

    A new biomimetic strategy of creating a quasi-biological system (an aqueous solution containing electrolytes, peptide, enzyme and coenzyme) for the preparation of gold nanoparticles with uniform and tunable sizes has been put forward and validated, adopting environmentally-friendly reducing agents and a biocompatible capping ligand in aqueous solution at room temperature. The biomimetic synthetic route has the characteristics for good stability of the resulting AuNPs capped with glutathione via strong Au-S bond in aqueous solution, an appropriate composition of the intermediate with a redox potential favorable for the biomimetic reduction under mild conditions, suitable pH values to adjust the rate of the reduction, and the addition of enzyme catalyzing the reduction. By only adjusting the concentration of the reducing agent NADPH, a series of AuNPs with narrow size-distribution could be controllably synthesized. This method of rational utilization of biological processes could provide a new way for the sustainable development of nanotechnology.A new biomimetic strategy of creating a quasi-biological system (an aqueous solution containing electrolytes, peptide, enzyme and coenzyme) for the preparation of gold nanoparticles with uniform and tunable sizes has been put forward and validated, adopting environmentally-friendly reducing agents and a biocompatible capping ligand in aqueous solution at room temperature. The biomimetic synthetic route has the characteristics for good stability of the resulting AuNPs capped with glutathione via strong Au-S bond in aqueous solution, an appropriate composition of the intermediate with a redox potential favorable for the biomimetic reduction under mild conditions, suitable pH values to adjust the rate of the reduction, and the addition of enzyme catalyzing the reduction. By only adjusting the concentration of the reducing agent NADPH, a series of AuNPs with narrow size-distribution could be controllably synthesized. This method

  17. Analysis of reflector antenna system including frequency selective surfaces

    NASA Astrophysics Data System (ADS)

    Zimmerman, M. L.; Lee, S. W.; Fujikawa, G.

    1992-10-01

    Frequency selective surfaces (FSS's) are often used in spaceborne applications of reflector antennas due to their ability to allow multiple feeds to utilize the same reflector dish. The problems inherent in evaluating the FSS separately from the reflector system are discussed. A method of integrating the FSS effects into the reflector system analysis is presented. An example is given for the proposed Advanced Tracking and Delay Relay Satellite System (ATDRSS) single-access triband reflector antenna.

  18. Analysis of reflector antenna system including frequency selective surfaces

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. L.; Lee, S. W.; Fujikawa, G.

    1992-01-01

    Frequency selective surfaces (FSS's) are often used in spaceborne applications of reflector antennas due to their ability to allow multiple feeds to utilize the same reflector dish. The problems inherent in evaluating the FSS separately from the reflector system are discussed. A method of integrating the FSS effects into the reflector system analysis is presented. An example is given for the proposed Advanced Tracking and Delay Relay Satellite System (ATDRSS) single-access triband reflector antenna.

  19. Exploration Depth of Multi-frequency Helicopter EM Systems

    NASA Astrophysics Data System (ADS)

    Yin, C.; Hodges, G.

    2004-05-01

    Due to the high resolution of hilicopter electromagnetic (HEM) systems, they are being widely used for shallow earth resistivity mapping problems. The traditional investigation of the exploration depth of a HEM system is based on the model of a single-frequency coil array over a layered earth. In this paper we extend the study to the multi-frequency HEM systems. We first determine for each frequency channel of a HEM system the maximal depth of a target, beyond which it cannot be identified from the EM signal. This is mathemically realized by assuming that the abnormal signal from the target is three times larger than the noise level of the HEM channel. Since each frequency channel of an HEM system has a different noise level and for different frequency channel the EM field has different penetration depth, we choose the biggest value of these depths as the depth of exploration. Different models are implemented in the study of this paper, including a layered earth model, a dipping plate or a dyke, a 3D ore body, etc. We use as example the Fugro DIGHEM system with three horizontal coplanar (HCP) coils (380 or 900, 7200, 56kHz) and two vertical coaxial (VCX) coils (900, 5500Hz). The following conclusions are obtained: 1. Except for a steeply dipping sheet, the HCP coil array has a larger depth of exploration than the VCX coil array; 2. The depth of exploration may be obtained from different frequency channels for different target geometries and different conductivity contrasts between the target and host rocks. This means that for a specific target geometry and conductivity contrast, we need to search such a frequency channel that offers the maximal value for depth of exploration; 3. Among the factors that influence the depth of exploration, the noise level of the HEM system is the key. The other factors include the geometry of the target and the conductivity contrast between the target and the host rocks, and the relative location between the HEM system and the target

  20. Electromechanical system frequency response equilization using three different methods

    NASA Astrophysics Data System (ADS)

    Prezelj, Jurij; Čudina, Mirko

    2007-01-01

    The frequency response of different electromechanical systems like sensors and actuators is in many cases the most important parameter for their evaluation. In some cases, when a short time delay does not play an important role and the flatness of frequency response is more important, an approximate of inverse system for frequency response compensation can be used. We equalized the frequency response of a non-minimum phase linear time-invariant electromechanical system using a digital finite impulse response (FIR) filter. Three different deconvolution methods for determination of the approximate of inverse filter impulse response were used and the results of the compensation using three different inverse filters are compared. The first method is based on the solution of the system of linear equations, while the second method is based on a simple direct inverse Fourier transformation. The third method uses an active noise control algorithm based on a least mean square adaptive algorithm. The results of all three methods can be applied in a FIR filter realized on DSP boards to perform real time compensation. The theoretical simulations are compared with experiments. Compensation of arbitrary systems is an interesting subject and it can be applied in numerous different fields from sensors and actuators to measurement and acoustics.

  1. Experimental study on resonant frequency of the thermoacoustic cooling system

    NASA Astrophysics Data System (ADS)

    Sakamoto, Shin-ichi; Hirano, Hiroyuki; Fujita, Takashi; Watanabe, Yoshiaki

    2006-05-01

    The purpose of our study is to construct a new cooling system applying the thermoacoustic effect. Stainless loop-tube is employed as our thermoacoustic cooling system and temperature decrease of 40 degrees C from the room temperature has been confirmed. In this paper, it is investigated that the relation between the viscosity boundary layer and the resonant frequency of the generated sound is investigated. Also, the sound pressure and temperature variation are observed with various total lengths of the loop-tube, with the view toward improvement in the cooling effect of the thermoacoustic cooling system. It was generally considered that the sound generated in the thermoacoustic cooling system is resonated with the tube length by 1 wavelength. However, when the total length of the loop-tube is over 2600 mm and inner pressure is 0.1 MPa, the resonant wavelength is 2. This is resulted from the influence of the viscosity boundary layer. It is found that the loop-tube decides the resonant frequency so that the thickness of the viscosity boundary layer is smaller than the stack channel radius. As a result, the resonant wavelength is 2 in a certain condition. The frequency is an important parameter for the thermoacoustic cooling system. From obtained results, one of the factors to select the frequency is found.

  2. Operating experience of the EBR-II intermediate heat exchanger and the steam generator system

    SciTech Connect

    Buschman, H.W.; Longua, K.J.; Penney, W.H.

    1983-01-01

    Experimental Breeder Reactor-II (EBR-II) is an experimental liquid metal fast breeder reactor located at the Idaho National Engineering Laboratory. It consists of an unmoderated, heterogeneous, sodium-cooled reactor with a nominal thermal power output of 62.5 MW; an intermediate closed loop of secondary sodium coolant; and a steam plant that produces 20 MW of electrical power through a conventional turbine generator. The EBR-II heat transport system continues to operate satisfactorily after 18 years. This represents about 89,000 hours of steaming, which results in a total integrated thermal power production of about 215,000 MWd. In this time, the steam generator has experienced over 580 plant startups and 349 reactor scrams. The plant capacity factor for the past five years has been in excess of 70%, and in fact has averaged almost 60% over the last thirteen years. This excellent record is partly attributable to the trouble-free operation of the steam generator which, aside from an initial construction tube-to-tubesheet weld defect, has had a plant availability of 100%.

  3. Distribution and origin of salinity in the surficial and intermediate aquifer systems, southwestern Florida

    USGS Publications Warehouse

    Schmerge, David L.

    2001-01-01

    Chloride concentrations in the surficial and intermediate aquifer systems in southwestern Florida indicate a general trend of increasing salinity coastward and with depth. There are some notable exceptions to this trend. Brackish water is present in the sandstone and mid-Hawthorn aquifers in several inland areas in Lee County. In an area near the coast in Collier County, the lower Tamiami aquifer contains freshwater, with brackish water present farther inland. Saline water is present in the lower Tamiami aquifer along the coast in Collier County, but water is brackish in the underlying mid-Hawthorn and Upper Floridan aquifers. The analyses of major ions, hydrogen and oxygen isotopes, and strontium isotopes indicate the primary sources of salinity are underlying aquifers and the Gulf of Mexico. Based on these data, much of the salinity is from upward leakage of brackish water from underlying aquifers. Discharge as diffuse upward leakage and artesian wells are two possible pathways of saltwater intrusion from underlying aquifers. Artesian wells open to multiple aquifers have been pathways of saltwater intrusion in the sandstone and mid-Hawthorn aquifers in much of Lee County. The source of brackish water in the lower Tamiami and mid-Hawthorn aquifers in Collier County may be natural diffuse leakage from underlying aquifers. The source of the saline water in the lower Tamiami aquifer in Collier County is apparently the Gulf of Mexico; it is unclear however, whether this saline water is residual water from former Pleistocene sea invasions or recent saltwater intrusion.

  4. Visualization and Classification of Power System Frequency Data Streams

    SciTech Connect

    Bank, Jason N; Omitaomu, Olufemi A; Fernandez, Steven J; Liu, Yilu

    2009-01-01

    Two challenges in the realization of the smart grid technology are the ability to visualize the deluge of expected data streams for global situational awareness and the ability to detect disruptive and classify events from spatially-distributed high-speed power system frequency measurements while minimizing false alarms and eliminating missed detection. This paper presents an interactive visualization model for high speed power system frequency data streams that presents both local and global views of the data streams for decision making process. It also presents a K-Median for clustering and identifying disruptive events in spatially-distributed data streams. The results from experimental evaluation on a variety of datasets show that K-Median achieve better performance and empowers analysts with the ability to make sense of a deluge of frequency measurements in a real-time situation.

  5. Radio frequency telemetry system for sensors and actuators

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor); Miranda, Felix A. (Inventor)

    2003-01-01

    The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote powering/receiving device. Such technology has many applications, but is especially useful in the biomedical area.

  6. Radio Frequency Telemetry System for Sensors and Actuators

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor); Miranda, Felix A. (Inventor)

    2003-01-01

    The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote poweringheceiving device. Such technology has many applications, but is especially useful in the biomedical area.

  7. Low-frequency switching voltage regulators for terrestrial photovoltaic systems

    NASA Technical Reports Server (NTRS)

    Delombard, R.

    1984-01-01

    The photovoltaic technology project and the stand alone applications project are discussed. Two types of low frequency switching type regulators were investigated. The design, operating characteristics and field application of these regulators is described. The regulators are small in size, low in cost, very low in power dissipation, reliable and allow considerable flexibility in system design.

  8. A Frequency-Domain Substructure System Identification Algorithm

    NASA Technical Reports Server (NTRS)

    Blades, Eric L.; Craig, Roy R., Jr.

    1996-01-01

    A new frequency-domain system identification algorithm is presented for system identification of substructures, such as payloads to be flown aboard the Space Shuttle. In the vibration test, all interface degrees of freedom where the substructure is connected to the carrier structure are either subjected to active excitation or are supported by a test stand with the reaction forces measured. The measured frequency-response data is used to obtain a linear, viscous-damped model with all interface-degree of freedom entries included. This model can then be used to validate analytical substructure models. This procedure makes it possible to obtain not only the fixed-interface modal data associated with a Craig-Bampton substructure model, but also the data associated with constraint modes. With this proposed algorithm, multiple-boundary-condition tests are not required, and test-stand dynamics is accounted for without requiring a separate modal test or finite element modeling of the test stand. Numerical simulations are used in examining the algorithm's ability to estimate valid reduced-order structural models. The algorithm's performance when frequency-response data covering narrow and broad frequency bandwidths is used as input is explored. Its performance when noise is added to the frequency-response data and the use of different least squares solution techniques are also examined. The identified reduced-order models are also compared for accuracy with other test-analysis models and a formulation for a Craig-Bampton test-analysis model is also presented.

  9. A parallel Atmosphere-Ocean Global Circulation Model of intermediate complexity for Earth system climate research

    NASA Astrophysics Data System (ADS)

    Silva, T. A.; Schmittner, A.

    2007-12-01

    We present the evolution of an Earth System model of intermediate complexity featuring an ocean global circulation model to include a fully coupled 3D primitive equations atmospheric model. The original Earth System climate model, UVic ESCM (Weaver et al. 2001), uses an ocean global circulation model coupled to a one layer atmospheric energy-moisture balance model. It also comprises a viscous-plastic rheology sea ice model, a mechanical land ice model, land surface, oceanic and terrestrial carbon models and a simple 3D marine ecosystem model (Schmittner et al. 2005). A spectral atmospheric, model, PUMA (Fraedrich et al. 2005), was coupled to the UVic ESCM to provide an atmosphere with nonlinear dynamics in target resolutions of T21, T31 and T42, as required. The coupling with the atmosphere, which involves data transfer, preprocessing and interpolation, is done through the OASIS3 coupler. During a run there are 2 + 2N parallel processes: the UVic ESCM, the Oasis3 coupler and the PUMA model with its domain split across 2N processes. The choice of N allows to balance more or less complex configurations of UVic model (e.g. higher level marine ecosystem model or number of biogeochemical tracers) with the atmospheric model at different resolutions, in order to maintain computational efficiency. The relatively simple parameterizations make this new atmosphere-ocean global circulation model much faster than a state-of-the-art Atmosphere-Ocean Global Circulation Model, and so optimally geared for decadal to millennial scale integrations. The latter require special care with the conservation of fluxes during coupling. A second order conservative interpolation method was applied (Jones 1999) and this is compared with the use of typical non-conservative methods.

  10. Regional projections of climate change using an Earth system model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Sobie, S. R.; Murdock, T. Q.

    2011-12-01

    Earth system models of intermediate complexity have been generally employed in experiments studying global temperature changes, carbon-cycle responses and millennial-scale climate variability. Their reduced computational demands mean many different greenhouse gas emissions scenarios can be examined, including exploring thresholds of dangerous climate change and geo-engineering schemes. In response to requests from users for more information on regional climate change under both more optimistic and more pessimistic emissions scenarios than the range provided by SRES, EMICs are able to produce additional climate change projections relatively rapidly. However, as a result of their parameterizations and reduced complexity, EMICs have been generally avoided when examining sub-global spatial scales in favour of GCMs or RCMs. To investigate these concerns, we compare responses to changes in radiative forcing from both the University of Victoria Earth system climate model and an ensemble of CMIP3 global climate models at a variety of sub-global spatial scales. Temperature trends and anomalies from commonly used intervals in the 20th and 21st centuries (e.g. 1961-1990, 2046-2065) are evaluated for both model types under standard emissions scenarios. Results indicate that the UVIC model produces statistically similar regional temperature responses as those of the ensemble average of the IPCC AR4 global climate models. Precipitation anomalies display fewer statistical matches with rainfall increases underestimated and snowfall decreases overestimated by the UVIC model. The results suggest regional consequences of more varied emissions scenarios could be examined in certain cases using the UVIC model (and potentially other EMICs) instead of GCMs or RCMs. A selection of regional climate change responses comparing the UVIC model to the AR4 ensemble average will be presented for a variety of areas.

  11. Effects of frequency/polarization allocations and the zero-dispersion frequency on FDM lightwave transmission systems

    NASA Astrophysics Data System (ADS)

    Onishi, Jun; Kojima, Shinya; Numai, Takahiro

    2008-07-01

    In long-haul frequency-division-multiplexing lightwave transmission systems, transmission characteristics are degraded by four-wave mixing (FWM) generated in optical fibers. To overcome this problem, several FWM suppression techniques have been reported. In this paper, dependence of FWM noises on frequency allocations, polarization allocations, and the zero-dispersion frequency is investigated. It is revealed that FWM noises are drastically decreased in frequency allocations such as equally spaced, repeated unequally spaced (RUS), equally spaced RUS, and unequally spaced RUS allocations by arranging polarization allocations of the channels with an increase in a separation between the channel frequencies and the zero-dispersion frequency.

  12. A very wide frequency band pulsed/IF radar system

    NASA Technical Reports Server (NTRS)

    Jones, D. N.; Burnside, W. D.

    1988-01-01

    A pulsed/IF radar for compact range radar cross section measurements has been developed which converts RF returns to a fixed IF, so that amplification and grating may be performed at one frequency. This permits the use of components which have optimal performance at this frequency which results in a corresponding improvement in performance. Sensitivity and dynamic range are calculated for this system and compared with our old radar, and the effect of pulse width on clutter level is also studied. Sensitivity and accuracy tests are included to verify the performance of the radar.

  13. Methods, Systems and Apparatuses for Radio Frequency Identification

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Chu, Andrew W. (Inventor); Lin, Gregory Y. (Inventor); Kennedy, Timothy F. (Inventor); Ngo, Phong H. (Inventor); Brown, Dewey T. (Inventor); Byerly, Diane (Inventor); Boose, Haley C. (Inventor)

    2015-01-01

    A system for radio frequency identification (RFID) includes an enclosure defining an interior region interior to the enclosure, and a feed for generating an electromagnetic field in the interior region in response to a signal received from an RFID reader via a radio frequency (RF) transmission line and, in response to the electromagnetic field, receiving a signal from an RFID sensor attached to an item in the interior region. The structure of the enclosure may be conductive and may include a metamaterial portion, an electromagnetically absorbing portion, or a wall extending in the interior region. Related apparatuses and methods for performing RFID are provided.

  14. Frequency Independent Design of Quasi-optical Systems

    NASA Astrophysics Data System (ADS)

    Gonzalez, Alvaro

    2016-02-01

    Beam propagation at millimeter and submillimeter wavelengths is well described by Gaussian beams and quasi-optical theory. Due to the general progress in THz technology, receiver and other quasi-optical systems in the THz range demand increasingly larger bandwidths. In this context, this paper presents a general design methodology for frequency independent quasi-optical systems, based on system matrix analysis. After the presentation of the general ideas, useful design equations are derived for the most common quasi-optical systems. Finally, the derived equations are validated by application to already deployed radio astronomy receivers.

  15. A HST spectroscopic study of QSOs with intermediate redshift damped Lyalpha systems

    NASA Astrophysics Data System (ADS)

    Boisse, Patrick; Le Brun, Vincent; Bergeron, Jacqueline; Deharveng, Jean-Michel

    1998-05-01

    We present HST spectra for a sample of six QSOs with intermediate redshift (z_ale 1.) damped Lyalpha systems. These observations aim at measuring the Hi column density and detect metal lines in order to investigate the metal enrichment of the gas, as well as the presence of neutral species, molecules and dust. All systems selected on the basis of 21 cm absorption and/or strong Feii lines relative to Mgii\\ ones turn out to have N(H{sc i}) larger than 10(20) cm(-2) . From our detection of weak lines from minor metals and already published optical data, we determine relative abundances of Si, Mn, Fe, Ni, Zn. In PKS 1229-021, we measure [Zn/H] = -0.5 at z_a = 0.3950 while in two other cases with intervening spiral galaxies and for which only [Fe/H] and [Mn/H] could be estimated, the metallicity could be close to solar. Thus, it appears that although the scatter of metallicities is as large at z_ale 1. as at high redshift, an increasing proportion of systems with metallicities =~ 30% solar are found when going to lower redshifts. Ci lines are tentatively detected in two systems. Given the low metallicity, the observed Ci/Hi ratio suggests that physical conditions in the absorbers are comparable to those in our Galaxy. In PKS 1229-021, the 21 cm absorption data combined with the new Lyalpha observations, imply a low temperature, T_s <= 200 K, for the z_a = 0.3950 absorbing gas. For the three systems in which they could be searched for, H_2 molecules are not detected with an upper limit of about 10(18) cm(-2) on N(H_2). No evidence is found for Galactic-type dust, except possibly in the 3C 286 z_a = 0.6922 system. Our results suggest that available observations may be biased against dust-rich absorbers. Further, when all available measurements of N(H{sc i}) and [Zn/H] are considered, a clear deficiency of systems with large N(H{sc i}) and high metallicity is apparent. We conclude that dust extinction causes a preferential selection of QSOs with intervening gas relatively

  16. Evaluation of frequency-selective reflector antenna systems

    NASA Technical Reports Server (NTRS)

    Wu, T. K.; Lee, S. W.; Zimmerman, M. L.

    1993-01-01

    The performance of a four-frequency (S/X/Ku/Ku bands) frequency-selective surface (FSS) with double-ring elements (the type of geometry particularly well suited for the circular polarization requirement of the NASA's Cassini project) is evaluated for a planar and a curved FSS subreflector in a dual reflector antenna system. Good agreement is obtained between the calculated and measured data for the planar FSS model. The FSS effects in a four-frequency Cassegrain reflector antenna were accurately evaluated by taking into account the surface curvature and the FSS subreflector's transmitted/reflected field variation as functions of the polarization and the incident angles with respect to the local coordinates.

  17. Radio frequency communication system utilizing radiating transmission lines

    DOEpatents

    Struven, Warren C.

    1984-01-01

    A radio communication system for use in tunnels, mines, buildings or other shielded locations in which a pair of radiating transmission lines (30), (31) extend through such location in spaced coextensive relation to each other. Each transmission line (30), (31) has at least one unidirectional amplifier (32), (33) interposed therein with the sense of the unidirectional amplifier (32) of one transmission line (30) being opposite to the sense of the unidirectional amplifier (33) of the other transmission line (31). Each of the amplifiers (32), (33) has a gain which is less than the coupling loss between the transmission lines (30), (31). Two or more mobile transceivers (35) in the location served by the system are coupled to the transmission lines (30), (31) by electromagnetic wave propagation in space in order to communicate directly with each other at a given radio frequency within the frequency range of the system.

  18. Dual-Frequency Airborne Scanning Rain Radar Antenna System

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad A.; Green, Ken

    2004-01-01

    A compact, dual-frequency, dual-polarization, wide-angle-scanning antenna system has been developed as part of an airborne instrument for measuring rainfall. This system is an upgraded version of a prior single-frequency airborne rain radar antenna system and was designed to satisfy stringent requirements. One particularly stringent combination of requirements is to generate two dual-polarization (horizontal and vertical polarizations) beams at both frequencies (13.405 and 35.605 GHz) in such a way that the beams radiated from the antenna point in the same direction, have 3-dB angular widths that match within 25 percent, and have low sidelobe levels over a wide scan angle at each polarization-and-frequency combination. In addition, the system is required to exhibit low voltage standing-wave ratios at both frequencies. The system (see figure) includes a flat elliptical scanning reflector and a stationary offset paraboloidal reflector illuminated by a common-aperture feed system that comprises a corrugated horn with four input ports one port for each of the four frequency-and-polarization combinations. The feed horn is designed to simultaneously (1) under-illuminate the reflectors 35.605 GHz and (2) illuminate the reflectors with a 15-dB edge taper at 13.405 GHz. The scanning mirror is rotated in azimuth to scan the antenna beam over an angular range of 20 in the cross-track direction for wide swath coverage, and in elevation to compensate for the motion of the aircraft. The design of common-aperture feed horn makes it possible to obtain the required absolute gain and low side-lobe levels in wide-angle beam scanning. The combination of the common-aperture feed horn with the small (0.3) focal-length-to-diameter ratio of the paraboloidal reflector makes it possible for the overall system to be compact enough that it can be mounted on a DC-8 airplane.

  19. A precise GPS-based time and frequency system

    NASA Technical Reports Server (NTRS)

    Mcnabb, Jack; Fossler, Earl

    1993-01-01

    An approach to implementing a compact, highly reliable and precise Master Time and Frequency subsystem usable in a variety of applications is described. These applications include, among others, Satellite Ground Terminals, Range Timing Stations, Communications Terminals, and Power Station Timing subsystems. All time and frequency output signals are locked to Universal Time via the GPS Satellite system. The system provides for continued output of precise signals in the event of GPS signal interruption from antenna or lead-in breakage or other causes. Cost/performance tradeoffs affecting system accuracy over the short, medium, and long term are discussed. A unique approach to redundant system design provides an architecture with the reliability advantage of triple-redundant majority voting and the cost advantages of dual-redundant elements. The system can be configured to output a variety of precise time and frequency signals and the design can be tailored to output as few, or as many, types and quantities of signals as are required by the application.

  20. Coalignment of microtubules, cytokeratin intermediate filaments, and collagen fibrils in a collagen-secreting cell system.

    PubMed

    McBeath, E; Fujiwara, K

    1989-12-01

    The distribution of microtubules and intermediate filaments in the collagen-secreting scleroblasts of the goldfish scale was investigated by immunofluorescence and electron microscopy. Many of the microtubules and cytokeratin type intermediate filaments formed bundles that were aligned with the underlying, parallel collagen fibrils. The intermediate filament bundles were evenly spaced and located adjacent to the basal plasma membrane. The microtubules, on the other hand, were located further away from the membrane, although many were found very close to the intermediate filament bundles. No detectable change was observed in scleroblast microtubules when cells on scales were treated with colchicine or cooled (greater than or equal to 0 degrees C) for up to 1 h. Cells had to be cooled overnight before the microtubules were affected. The final number and length of the microtubules in the cell depended only on the final steady-state temperature and not the temperature history of the scale cell, and steady state was reached more slowly at colder temperatures. The microtubules but not the intermediate filaments rapidly (within 5 min) and reversibly depolymerized when cells were chilled to -2 approximately -4 degrees C. When chilled cells were warmed, the microtubules polymerized back, within 15 min at room temperature, to the same pattern of parallel coalignment with the underlying collagen. They appeared to repolymerize via two different pathways: (1) a radial growth outwards from the microtubule organizing center followed by a progressive realignment with the underlying collagen and (2) a gradual and simultaneous polymerization along cold-stable, antitubulin staining fibers. These fibers were also aligned with the collagen fibrils and may be related to the aligned intermediate filaments. PMID:2483378

  1. NBS frequency measurement system from a user's viewpoint

    SciTech Connect

    Booker, S.R.; Jones, M.C.

    1984-01-01

    During 1983, the National Bureau of Standards announced the availability of a new Frequency Measurement Service for standard oscillators of high stability. Two standards laboratories at Sandia National Laboratories have subscribed to that service, and as a result have been supplied by the National Bureau of Standards with hardware, software, consultation, and a continuing program of standard oscillator evaluation. This paper discusses the motivation for subscribing to the new service, experience in setting up the systems at Sandia, system reliability, some preliminary observations about accuracy, and possible system enhancements. All of the material is presented from the viewpoint of a new user of the service.

  2. Frequency stabilized near-IR laser system for optical communications

    NASA Astrophysics Data System (ADS)

    Růžička, B.; Číp, O.; Lazar, J.

    2005-08-01

    We present a design of a stabilized laser system, an etalon of the optical frequency at the 1.5 μm band following the demands of the telecommunication industry in the Czech Republic. Our laser system employs a DFB laser diode in a two stage stabilizing scheme. The linear absorption arrangement with an acetylene filled absorption cell of a pressure about 1 kPa is used to lock the laser to the Doppler-broadened lines. To achieve a reliable and robust stabilization of the laser frequency we arranged a two-loop digital servo-system overcoming the problem of a narrow locking range of the detected transition. The wavelength of the laser is modulated by current and the servo-control and tuning is performed by a fast and precise thermal control. To achieve the resolution of the weak sub-Doppler transitions we assembled a locking scheme via frequency-modulation spectroscopy to the high finesse cavity. The system is assembled using predominantly fibre-optic components. A technology of acetylene absorption cells with AR coated windows is presented as well.

  3. Laser frequency stabilization to excited state transitions using electromagnetically induced transparency in a cascade system

    SciTech Connect

    Abel, R. P.; Mohapatra, A. K.; Bason, M. G.; Pritchard, J. D.; Weatherill, K. J.; Raitzsch, U.; Adams, C. S.

    2009-02-16

    We demonstrate laser frequency stabilization to excited state transitions using cascade electromagnetically induced transparency. Using a room temperature Rb vapor cell as a reference, we stabilize a first diode laser to the D{sub 2} transition and a second laser to a transition from the intermediate 5P{sub 3/2} state to a highly excited state with principal quantum number n=19-70. A combined laser linewidth of 280{+-}50 kHz over a 100 {mu}s time period is achieved. This method may be applied generally to any cascade system and allows laser stabilization to an atomic reference in the absence of a direct absorption signal.

  4. Petrological mapping of Volcanic Plumbing Systems using amphiboles in mixed intermediate magmas

    NASA Astrophysics Data System (ADS)

    Kiss, Balázs; Harangi, SzZabolcs; Hauzenberger, Christoph; Ntaflos, Theodoros; Mason, Paul R. D.

    2016-04-01

    Petrological mapping of volcanic plumbing systems (VPS) is essential to understand the magma evolution and to interpret geophysical signals of monitored volcanoes. The mapping includes the determination of the compositions of magmas feed the system and their storage depths. Intermediate magmas are usually formed by magma mixing a processes that mask the real compositional variation of magmas feed the VPS. However phenocrysts can preserve this information in their chemical stratigraphy. Amphibole can be a powerful tool in these studies because it can incorporate petrogenetically important trace elements primarily controlled by the coexisting melt composition, additionally the major element composition can be used to calculate pressure. We studied the zoning, texture and major and trace element composition of amphiboles from the Ciomadul, a late pleistocen dacite volcano. The erupted dacites contain abundant amphibole phenocrysts. Amphibole coexist with all of the rock forming minerals (e.g. with quartz or with olivine) indicating their diverse origin. The amphiboles show large major element compositional variation (e.g. Al2O3: 6-15 wt%) accompanied with large variation in trace element (e.g. Cr: 10-3000 ppm, Sr: 55-855 ppm, Eu/Eu*: 0.62-1.19) even in a single sample or single crystal and they represent antecryst (reworked) and phenocryst (in situ crystallized) populations. Such a large compositional variation of amphiboles is commonly observed at andesite-dacite arc volcanoes. Hornblendes (antecryst1) have low Al, Mg/Fe, and negative Eu-anomaly; they equilibrated with rhyolitic melt at near-solidus temperature. Antecryst2 is represented by Cr-, Mg-rich amphiboles; they can contain Cr-spinel inclusions suggesting near-liquidus crystallization from primitive mafic melts. Phenocrysts show large compositional variation sample by sample that is different from the antecrysts suggesting variable pre-eruptive conditions. The antecrysts are derived from a stratified (mafic

  5. Historical and idealized climate model experiments: an intercomparison of Earth system models of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Eby, M.; Weaver, A. J.; Alexander, K.; Zickfeld, K.; Abe-Ouchi, A.; Cimatoribus, A. A.; Crespin, E.; Drijfhout, S. S.; Edwards, N. R.; Eliseev, A. V.; Feulner, G.; Fichefet, T.; Forest, C. E.; Goosse, H.; Holden, P. B.; Joos, F.; Kawamiya, M.; Kicklighter, D.; Kienert, H.; Matsumoto, K.; Mokhov, I. I.; Monier, E.; Olsen, S. M.; Pedersen, J. O. P.; Perrette, M.; Philippon-Berthier, G.; Ridgwell, A.; Schlosser, A.; Schneider von Deimling, T.; Shaffer, G.; Smith, R. S.; Spahni, R.; Sokolov, A. P.; Steinacher, M.; Tachiiri, K.; Tokos, K.; Yoshimori, M.; Zeng, N.; Zhao, F.

    2013-05-01

    Both historical and idealized climate model experiments are performed with a variety of Earth system models of intermediate complexity (EMICs) as part of a community contribution to the Intergovernmental Panel on Climate Change Fifth Assessment Report. Historical simulations start at 850 CE and continue through to 2005. The standard simulations include changes in forcing from solar luminosity, Earth's orbital configuration, CO2, additional greenhouse gases, land use, and sulphate and volcanic aerosols. In spite of very different modelled pre-industrial global surface air temperatures, overall 20th century trends in surface air temperature and carbon uptake are reasonably well simulated when compared to observed trends. Land carbon fluxes show much more variation between models than ocean carbon fluxes, and recent land fluxes appear to be slightly underestimated. It is possible that recent modelled climate trends or climate-carbon feedbacks are overestimated resulting in too much land carbon loss or that carbon uptake due to CO2 and/or nitrogen fertilization is underestimated. Several one thousand year long, idealized, 2 × and 4 × CO2 experiments are used to quantify standard model characteristics, including transient and equilibrium climate sensitivities, and climate-carbon feedbacks. The values from EMICs generally fall within the range given by general circulation models. Seven additional historical simulations, each including a single specified forcing, are used to assess the contributions of different climate forcings to the overall climate and carbon cycle response. The response of surface air temperature is the linear sum of the individual forcings, while the carbon cycle response shows a non-linear interaction between land-use change and CO2 forcings for some models. Finally, the preindustrial portions of the last millennium simulations are used to assess historical model carbon-climate feedbacks. Given the specified forcing, there is a tendency for the

  6. Large-N correlator systems for low frequency radio astronomy

    NASA Astrophysics Data System (ADS)

    Foster, Griffin

    Low frequency radio astronomy has entered a second golden age driven by the development of a new class of large-N interferometric arrays. The low frequency array (LOFAR) and a number of redshifted HI Epoch of Reionization (EoR) arrays are currently undergoing commission and regularly observing. Future arrays of unprecedented sensitivity and resolutions at low frequencies, such as the square kilometer array (SKA) and the hydrogen epoch of reionization array (HERA), are in development. The combination of advancements in specialized field programmable gate array (FPGA) hardware for signal processing, computing and graphics processing unit (GPU) resources, and new imaging and calibration algorithms has opened up the oft underused radio band below 300 MHz. These interferometric arrays require efficient implementation of digital signal processing (DSP) hardware to compute the baseline correlations. FPGA technology provides an optimal platform to develop new correlators. The significant growth in data rates from these systems requires automated software to reduce the correlations in real time before storing the data products to disk. Low frequency, widefield observations introduce a number of unique calibration and imaging challenges. The efficient implementation of FX correlators using FPGA hardware is presented. Two correlators have been developed, one for the 32 element BEST-2 array at Medicina Observatory and the other for the 96 element LOFAR station at Chilbolton Observatory. In addition, calibration and imaging software has been developed for each system which makes use of the radio interferometry measurement equation (RIME) to derive calibrations. A process for generating sky maps from widefield LOFAR station observations is presented. Shapelets, a method of modelling extended structures such as resolved sources and beam patterns has been adapted for radio astronomy use to further improve system calibration. Scaling of computing technology allows for the

  7. Signal Adaptive System for Space/Spatial-Frequency Analysis

    NASA Astrophysics Data System (ADS)

    Ivanović, Veselin N.; Jovanovski, Srdjan

    2010-12-01

    This paper outlines the development of a multiple-clock-cycle implementation (MCI) of a signal adaptive two-dimensional (2D) system for space/spatial-frequency (S/SF) signal analysis. The design is based on a method for improved S/SF representation of the analyzed 2D signals, also proposed here. The proposed MCI design optimizes critical design performances related to hardware complexity, making it a suitable system for real time implementation on an integrated chip. Additionally, the design allows the implemented system to take a variable number of clock cycles (CLKs) (the only necessary ones regarding desirable—2D Wigner distribution-presentation of autoterms) in different frequency-frequency points during the execution. This ability represents a major advantage of the proposed design which helps to optimize the time required for execution and produce an improved, cross-terms-free S/SF signal representation. The design has been verified by a field-programmable gate array (FPGA) circuit design, capable of performing S/SF analysis of 2D signals in real time.

  8. Development of a frequency-domain electromagnetic scattering measurement system

    NASA Astrophysics Data System (ADS)

    Oh, Kenneth K.

    1993-12-01

    This thesis describes the development of a system for measuring frequency-domain scattered fields in the Transient Electromagnetic Scattering Range at the Naval Postgraduate School. The new system employs a stepped-frequency CW waveform and utilizes an HP-8510B network analyzer as an RF front-end and a coherent receiver. A pair of AEL H1498 antennas was installed to cover a frequency range of 2 GHz to 18 GHz. An HP-82300C BASIC Language Processor was installed on a COMPAQ Deskpro-386 PC, and an HP-BASIC program was developed for remote control of the HP-8510B with data acquisition over the HPIB bus. A post-processing algorithm was created using MatLab for background subtraction, calibration, and deconvolution. A set of RCS measurements was made using various size spheres, and the postprocessing outputs were compared to computed values. Good agreement between these measurements and computed data indicates excellent accuracy of the measurement system and valid operations of the postprocessing algorithm.

  9. Description of the Earth system model of intermediate complexity LOVECLIM version 1.2

    NASA Astrophysics Data System (ADS)

    Goosse, H.; Brovkin, V.; Fichefet, T.; Haarsma, R.; Huybrechts, P.; Jongma, J.; Mouchet, A.; Selten, F.; Barriat, P.-Y.; Campin, J.-M.; Deleersnijder, E.; Driesschaert, E.; Goelzer, H.; Janssens, I.; Loutre, M.-F.; Morales Maqueda, M. A.; Opsteegh, T.; Mathieu, P.-P.; Munhoven, G.; Pettersson, E. J.; Renssen, H.; Roche, D. M.; Schaeffer, M.; Tartinville, B.; Timmermann, A.; Weber, S. L.

    2010-03-01

    The main characteristics of the new version 1.2 of the three-dimensional Earth system model of intermediate complexity LOVECLIM are briefly described. LOVECLIM 1.2 includes representations of the atmosphere, the ocean and sea ice, the land surface (including vegetation), the ice sheets, the icebergs and the carbon cycle. The atmospheric component is ECBilt2, a T21, 3-level quasi-geostrophic model. The oceanic component is CLIO3, which is made up of an ocean general circulation model coupled to a comprehensive thermodynamic-dynamic sea-ice model. Its horizontal resolution is 3° by 3°, and there are 20 levels in the ocean. ECBilt-CLIO is coupled to VECODE, a vegetation model that simulates the dynamics of two main terrestrial plant functional types, trees and grasses, as well as desert. VECODE also simulates the evolution of the carbon cycle over land while the oceanic carbon cycle is represented in LOCH, a comprehensive model that takes into account both the solubility and biological pumps. The ice sheet component AGISM is made up of a three-dimensional thermomechanical model of the ice sheet flow, a visco-elastic bedrock model and a model of the mass balance at the ice-atmosphere and ice ocean interfaces. For both the Greenland and Antarctic ice sheets, calculations are made on a 10 km by 10 km resolution grid with 31 sigma levels. LOVECLIM 1.2 reproduces well the major characteristics of the observed climate both for present-day conditions and for key past periods such as the last millennium, the mid-Holocene and the Last Glacial Maximum. However, despite some improvements compared to earlier versions, some biases are still present in the model. The most serious ones are mainly located at low latitudes with an overestimation of the temperature there, a too symmetric distribution of precipitation between the two hemispheres, an overestimation of precipitation and vegetation cover in the subtropics. In addition, the atmospheric circulation is too weak. The model

  10. Description of the Earth system model of intermediate complexity LOVECLIM version 1.2

    NASA Astrophysics Data System (ADS)

    Goosse, H.; Brovkin, V.; Fichefet, T.; Haarsma, R.; Huybrechts, P.; Jongma, J.; Mouchet, A.; Selten, F.; Barriat, P.-Y.; Campin, J.-M.; Deleersnijder, E.; Driesschaert, E.; Goelzer, H.; Janssens, I.; Loutre, M.-F.; Morales Maqueda, M. A.; Opsteegh, T.; Mathieu, P.-P.; Munhoven, G.; Pettersson, E. J.; Renssen, H.; Roche, D. M.; Schaeffer, M.; Tartinville, B.; Timmermann, A.; Weber, S. L.

    2010-11-01

    The main characteristics of the new version 1.2 of the three-dimensional Earth system model of intermediate complexity LOVECLIM are briefly described. LOVECLIM 1.2 includes representations of the atmosphere, the ocean and sea ice, the land surface (including vegetation), the ice sheets, the icebergs and the carbon cycle. The atmospheric component is ECBilt2, a T21, 3-level quasi-geostrophic model. The ocean component is CLIO3, which consists of an ocean general circulation model coupled to a comprehensive thermodynamic-dynamic sea-ice model. Its horizontal resolution is of 3° by 3°, and there are 20 levels in the ocean. ECBilt-CLIO is coupled to VECODE, a vegetation model that simulates the dynamics of two main terrestrial plant functional types, trees and grasses, as well as desert. VECODE also simulates the evolution of the carbon cycle over land while the ocean carbon cycle is represented by LOCH, a comprehensive model that takes into account both the solubility and biological pumps. The ice sheet component AGISM is made up of a three-dimensional thermomechanical model of the ice sheet flow, a visco-elastic bedrock model and a model of the mass balance at the ice-atmosphere and ice-ocean interfaces. For both the Greenland and Antarctic ice sheets, calculations are made on a 10 km by 10 km resolution grid with 31 sigma levels. LOVECLIM1.2 reproduces well the major characteristics of the observed climate both for present-day conditions and for key past periods such as the last millennium, the mid-Holocene and the Last Glacial Maximum. However, despite some improvements compared to earlier versions, some biases are still present in the model. The most serious ones are mainly located at low latitudes with an overestimation of the temperature there, a too symmetric distribution of precipitation between the two hemispheres, and an overestimation of precipitation and vegetation cover in the subtropics. In addition, the atmospheric circulation is too weak. The model

  11. Characterization of a Novel Melt Curve by Use of the Roche LightCycler HSV 1/2 Analyte-Specific Reagent Real-Time PCR Assay: Frequencies of This Novel (Low) Melt Curve and Commonly Encountered (Intermediate) Melt Curves

    PubMed Central

    Almradi, Amro; Espy, Mark J.; Prada, Anne E.; Gibson, John P.; Pritt, Bobbi S.

    2014-01-01

    We characterize a novel probe binding-site polymorphism detectable solely by melt curve analysis using the Roche LightCycler HSV 1/2 analyte-specific reagent real-time PCR assay. The frequencies of this novel (47°C) and previously described intermediate (60 to 62°C) melt curves were 0.016% and 4.9%, respectively. PMID:24352998

  12. Spontaneous formation of intermediate phases and dynamics of interfacial tension in water-nonionic surfactant-octane systems

    SciTech Connect

    Svitova, T.F.; Smirnova, Yu.P.; Pisarev, S.A.

    1994-05-01

    The kinetics of the spontaneous formation of intermediate phases in aqueous solutions of ethoxylated iso-nonylphenols (iso-C{sub 9}PhEO{sub n}, where n = 5-10)-octane systems was studied at 25{degree}C. The maximum rate of the formation of intermediate phases at this temperature was observed when the number of ethoxy-groups n was 6. The dynamic interfacial tension at the boundary between the aqueous solutions of the surfactants and octane were measured using drop volume and spinning drop methods. The rate of the interfacials tension decrease was maximum and the equilibrium interfacial tension was minimum also at n = 6. A correlation between the dynamics of interfacial processes and the equilibrium phase state of the water-nonionic surfactant-hydrocarbon systems was found for the first time.

  13. Characterizing DSN System Frequency Stability with Spacecraft Tracking Data

    NASA Technical Reports Server (NTRS)

    Pham, T.; Machuzak, R.; Bedrossian, A.

    2010-01-01

    This paper describes a recent effort in characterizing frequency stability performance of the ground system in the NASA Deep Space Network (DSN). Unlike the traditional approach where performance is obtained from special calibration sessions that are both time consuming and require manual setup, the new method taps into the daily spacecraft tracking data. This method significantly increases the amount of data available for analysis, roughly by two orders of magnitude; making it possible to conduct trend analysis with reasonable confidence. Since the system is monitored daily, any significant variation in performance can be detected timely. This helps the DSN maintain its performance commitment to customers.

  14. Energetics of Intermediate Temperature Solid Oxide Fuel Cell Electrolytes: Singly and Doubly doped Ceria Systems

    NASA Astrophysics Data System (ADS)

    Buyukkilic, Salih

    Solid oxide fuel cells (SOFCs) have potential to convert chemical energy directly to electrical energy with high efficiency, with only water vapor as a by-product. However, the requirement of extremely high operating temperatures (~1000 °C) limits the use of SOFCs to only in large scale stationary applications. In order to make SOFCs a viable energy solution, enormous effort has been focused on lowering the operating temperatures below 700 °C. A low temperature operation would reduce manufacturing costs by slowing component degradation, lessening thermal mismatch problems, and sharply reducing costs of operation. In order to optimize SOFC applications, it is critical to understand the thermodynamic stabilities of electrolytes since they directly influence device stability, sustainability and performance. Rare-earth doped ceria electrolytes have emerged as promising materials for SOFC applications due to their high ionic conductivity at the intermediate temperatures (500--700 °C). However there is a fundamental lack of understanding regarding their structure, thermodynamic stability and properties. Therefore, the enthalpies of formation from constituent oxides and ionic conductivities were determined to investigate a relationship between the stability, composition, structural defects and ionic conductivity in rare earth doped ceria systems. For singly doped ceria electrolytes, we investigated the solid solution phase of bulk Ce1-xLnxO2-0.5x where Ln = Sm and Nd (0 ≤ x ≤ 0.30) and analyzed their enthalpies of formation, mixing and association, and bulk ionic conductivities while considering cation size mismatch and defect associations. It was shown that for ambient temperatures in the dilute dopant region, the positive heat of formation reaches a maximum as the system becomes increasingly less stable due to size mismatch. In concentrated region, stabilization to a certain solubility limit was observed probably due to the defect association of trivalent cations

  15. High-frequency-link based power electronics in power systems

    NASA Astrophysics Data System (ADS)

    Sree, Hari

    Power quality has become a serious concern to many utility customers in recent times. Among the many power quality problems, voltage sags are one of the most common and most mischievous, affecting industrial and commercial customers. They are primarily caused by power system faults at the transmission and distribution level, and thus, are mostly unavoidable. Their effect depends on the equipment sensitivities to the magnitude and duration of these sags and each can cost an industry up to few million dollars. To counter these limitations, many solutions at the customer end have been proposed which include Constant Voltage Transformers (CVT's), UPS and line frequency transformer based Dynamic Voltage Restorer (DVR). These approaches have their respective limitations with regard to capabilities, size and cost. This research proposes a new approach to mitigating these voltage sags involving the use of high frequency transformer link. Suitable switching logic and control strategies have been implemented. The proposed approach in a one-phase application is verified with computer simulations and by a hardware proof-of-concept prototype. Application to three-phase system is verified through simulations. Application of high frequency transformers in other utility applications such as active filters and static compensators is also looked at.

  16. Microfabricated multi-frequency particle impedance characterization system

    SciTech Connect

    Fuller, C K; Hamilton, J; Ackler, H; Krulevitch, P; Boser, B; Eldredge, A; Becker, F; Yang, J; Gascoyne, P

    2000-03-01

    We have developed a microfabricated flow-through impedance characterization system capable of performing AC, multi-frequency measurements on cells and other particles. The sensor measures both the resistive and reactive impedance of passing particles, at rates of up to 100 particles per second. Its operational bandwidth approaches 10 MHz with a signal-to-noise ratio of approximately 40 dB. Particle impedance is measured at three or more frequencies simultaneously, enabling the derivation of multiple particle parameters. This constitutes an improvement to the well-established technique of DC particle sizing via the Coulter Principle. Human peripheral blood granulocyte radius, membrane capacitance, and cytoplasmic conductivity were measured (r = 4.1 {micro}m, C{sub mem} = 0.9 {micro}F/cm{sup 2}, {sigma}{sub int} = 0.66 S/m) and were found to be consistent with published values.

  17. Multifunction tests of a frequency domain based flutter suppression system

    NASA Technical Reports Server (NTRS)

    Christhilf, David M.; Adams, William M., Jr.

    1992-01-01

    This paper describes the process of analysis, design, digital implementation and subsonic testing of an active controls flutter suppression system for a full span, free-to-roll wind-tunnel model of an advanced fighter concept. The design technique employed a frequency domain representation of the plant and used optimization techniques to generate a robust multi-input/multi-output controller. During testing in a fixed-in-roll configuration, simultaneous suppression of both symmetric and antisymmetric flutter was successfully demonstrated. For a free-to-roll configuration, symmetric flutter was suppressed to the limit of the tunnel test envelope. During aggressive rolling maneuvers above the open-loop flutter boundary, simultaneous flutter suppression and maneuver load control were demonstrated. Finally, the flutter suppression controller was reoptimized overnight during the test using combined experimental and analytical frequency domain data, resulting in improved stability robustness.

  18. Multifunction tests of a frequency domain based flutter suppression system

    NASA Technical Reports Server (NTRS)

    Christhilf, David M.; Adams, William M., Jr.

    1992-01-01

    The process is described of analysis, design, digital implementation, and subsonic testing of an active control flutter suppression system for a full span, free-to-roll wind tunnel model of an advanced fighter concept. The design technique uses a frequency domain representation of the plant and used optimization techniques to generate a robust multi input/multi output controller. During testing in a fixed-in-roll configuration, simultaneous suppression of both symmetric and antisymmetric flutter was successfully shown. For a free-to-roll configuration, symmetric flutter was suppressed to the limit of the tunnel test envelope. During aggressive rolling maneuvers above the open-loop flutter boundary, simultaneous flutter suppression and maneuver load control were demonstrated. Finally, the flutter damping controller was reoptimized overnight during the test using combined experimental and analytical frequency domain data, resulting in improved stability robustness.

  19. The Low Frequency Aeroacoustics of Buried Nozzle Systems

    NASA Astrophysics Data System (ADS)

    Taylor, M. V.; Crighton, D. G.; Cargill, A. M.

    1993-05-01

    A simplified model of a "buried nozzle" aeroengine system is considered. The primary flow issues into a co-annular flow within a mixing chamber, and then the co-annular flow issues into the ambient medium from a secondary nozzle. Within the mixing chamber only fine scale mixing takes place, and shear layers within the mixing chamber and downstream of the secondary nozzle are assumed to sustain large scale instability waves. Excitation of this system is provided by low frequency plane waves, incident from upstream on the primary nozzle (and emanating from combustion processes in the hot core of an aeroengine). The response of this system, in the acoustic far field and in the mixing chamber, is obtained analytically from the asymptotic solution, at low frequency, of model sub-problems the solutions of which determine the wave reflection and transmission processes at the primary and secondary nozzles. In these sub-problems the shear layers are represented by vortex sheets and the nozzle walls by semi-infinite circular ducts, with Kutta conditions imposed on the unsteady flow at the primary and secondary nozzle lips. Analytical descriptions are given of the various wave modes (quasi-plane acoustic waves, and instability waves localized on the primary and secondary shear layers), of the acoustic field strength and directivity (essentially monopole, dipole and quadrupole fields), and of the conditions under which near-resonant response may occur, with large amplitudes of the perturbations in the mixing chamber and in the acoustic field.

  20. Ultra low frequency electromagnetic fire alarm system for underground mines

    SciTech Connect

    Not Available

    1991-01-01

    During an underground mine fire, air can be rapidly depleted of oxygen and contaminated with smoke and toxic fire gases. Any delay in warning miners could have disastrous consequences. Unfortunately, present mine fire alarm systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in mine area coverage. Recent research by the U.S. Bureau of Mines has demonstrated that ultra-low-frequency electromagnetic signaling can be used for an underground mine fire alarm. In field tests of prototype equipment at five mines, electromagnetic signals from 630 to 2,000 Hz were transmitted through mine rock for distances as great as 1,645 m to an intrinsically safe receiver. The prototype system uses off-the-shelf components and state-of-the-art technology to ensure high reliability and low cost. When utilized, this technology would enable simultaneous and instantaneous warning of all underground personnel, regardless of their location or work activity, thereby increasing the likelihood of their successfully escaping a mine disaster. This paper presents the theoretical basis for through-the-rock ultra-low-frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.

  1. Optimal Frequency-Domain System Realization with Weighting

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Maghami, Peiman G.

    1999-01-01

    Several approaches are presented to identify an experimental system model directly from frequency response data. The formulation uses a matrix-fraction description as the model structure. Frequency weighting such as exponential weighting is introduced to solve a weighted least-squares problem to obtain the coefficient matrices for the matrix-fraction description. A multi-variable state-space model can then be formed using the coefficient matrices of the matrix-fraction description. Three different approaches are introduced to fine-tune the model using nonlinear programming methods to minimize the desired cost function. The first method uses an eigenvalue assignment technique to reassign a subset of system poles to improve the identified model. The second method deals with the model in the real Schur or modal form, reassigns a subset of system poles, and adjusts the columns (rows) of the input (output) influence matrix using a nonlinear optimizer. The third method also optimizes a subset of poles, but the input and output influence matrices are refined at every optimization step through least-squares procedures.

  2. Highly sensitive passive radio frequency identification based sensor systems

    NASA Astrophysics Data System (ADS)

    Wissenwasser, J.; Vellekoop, M.; Heer, R.

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments.

  3. Highly sensitive passive radio frequency identification based sensor systems.

    PubMed

    Wissenwasser, J; Vellekoop, M; Heer, R

    2010-02-01

    A novel platform for sensor applications based on radio frequency (rf) identification technology, where passive tags are powered by the rf-field of a reader, is presented. The sophisticated energy harvesting system of the tag enables a blanking of the rf-field for a defined period, while supplying the tag electronics with a highly stable voltage and a power of 25 mW for 100 ms. During this time, span measurements can be performed without interferences of the rf-field. The presented tags work without batteries and are designed for impedance measurements on microbiological cell cultures under physiological relevant conditions as well as in harsh environments. PMID:20192517

  4. Haemostatic role of intermediate filaments in adhered platelets: importance of the membranous system stability.

    PubMed

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Mondragón, Ricardo; Mondragón, Mónica; González, Sirenia; Galván, Iván J

    2013-09-01

    The role of platelets in coagulation and the haemostatic process was initially suggested two centuries ago, and under appropriate physiological stimuli, these undergo abrupt morphological changes, attaching and spreading on damaged endothelium, preventing bleeding. During the adhesion process, platelet cytoskeleton reorganizes generating compartments in which actin filaments, microtubules, and associated proteins are arranged in characteristic patterns mediating crucial events, such as centralization of their organelles, secretion of granule contents, aggregation with one another to form a haemostatic plug, and retraction of these aggregates. However, the role of Intermediate filaments during the platelet adhesion process has not been explored. J. Cell. Biochem. 114: 2050-2060, 2013. © 2013 Wiley Periodicals, Inc. PMID:23553987

  5. High efficiency coupling of radio frequency beams from the dual frequency gyrotron with a corrugated waveguide transmission system.

    PubMed

    Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Mitsunaka, Yoshika; Sakamoto, Keishi

    2013-01-01

    High efficiency coupling of the millimeter-wave output of the dual-frequency gyrotron with the transmission line was demonstrated. The dual-frequency gyrotron was design to produce similar beam profiles for two operation frequencies (170 GHz and 137 GHz). Using two RF beam reflecting mirrors in a matching optics unit (MOU), which are designed to transform the beam profile of the gyrotron output to the fundamental waveguide mode (HE(11) mode) at 170 GHz, high efficiency coupling was demonstrated for two frequencies. The measured mode purity of HE(11) mode was 96% at 170 GHz and 94% at 137 GHz operations with the identical mirrors at the fixed mirror position and angle. The results indicate that the significantly simple dual frequency system is realized by the gyrotron designed to output the similar beam profiles at different frequency operation. PMID:23387644

  6. System and method for tuning adjusting the central frequency of a laser while maintaining frequency stabilization to an external reference

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey (Inventor); Thorpe, James I. (Inventor); Numata, Kenji (Inventor)

    2011-01-01

    A method and system for stabilizing a laser to a frequency reference with an adjustable offset. The method locks a sideband signal generated by passing an incoming laser beam through the phase modulator to a frequency reference, and adjusts a carrier frequency relative to the locked sideband signal by changing a phase modulation frequency input to the phase modulator. The sideband signal can be a single sideband (SSB), dual sideband (DSB), or an electronic sideband (ESB) signal. Two separate electro-optic modulators can produce the DSB signal. The two electro-optic modulators can be a broadband modulator and a resonant modulator. With a DSB signal, the method can introduce two sinusoidal phase modulations at the phase modulator. With ESB signals, the method can further drive the optical phase modulator with an electrical signal with nominal frequency OMEGA(sub 1) that is phase modulated at a frequency OMEGA(sub 2)

  7. Effect of substrates and intermediate compounds on foaming in manure digestion systems.

    PubMed

    Boe, K; Kougias, P G; Pacheco, F; O-Thong, S; Angelidaki, I

    2012-01-01

    Manure contains several compounds that can potentially cause foaming during anaerobic digestion. Understanding the effect of substrates and intermediate compounds on foaming tendency and stability could facilitate strategies for foaming prevention and recovery of the process. In this study, the effect of physicochemical properties of substrates and intermediate compounds on liquid properties such as surface tension, surfactant property, and hydrophobicity were investigated and compared with the effect on foaming tendency and foam stability. The results showed that there was no consistent correlation between foaming potential and hydrophobicity, oil displacement area (ODA) or surface tension of the tested solutions, and the best way to determine the foaming property of the solution was to directly measure foaming tendency and foam stability. Na-oleate and acetic acid showed the highest potential to create foam in a manure digester. Moreover, high organic loading of lipids and protein, and high concentrations of acetic and butyric acids also showed a strong tendency to create foaming during anaerobic digestion. Due to their great ability to stabilize foam, high organic loadings of Na-oleate or gelatine were considered to be the main potential foaming problem. PMID:22949245

  8. Fault detection in rotor bearing systems using time frequency techniques

    NASA Astrophysics Data System (ADS)

    Chandra, N. Harish; Sekhar, A. S.

    2016-05-01

    Faults such as misalignment, rotor cracks and rotor to stator rub can exist collectively in rotor bearing systems. It is an important task for rotor dynamic personnel to monitor and detect faults in rotating machinery. In this paper, the rotor startup vibrations are utilized to solve the fault identification problem using time frequency techniques. Numerical simulations are performed through finite element analysis of the rotor bearing system with individual and collective combinations of faults as mentioned above. Three signal processing tools namely Short Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT) and Hilbert Huang Transform (HHT) are compared to evaluate their detection performance. The effect of addition of Signal to Noise ratio (SNR) on three time frequency techniques is presented. The comparative study is focused towards detecting the least possible level of the fault induced and the computational time consumed. The computation time consumed by HHT is very less when compared to CWT based diagnosis. However, for noisy data CWT is more preferred over HHT. To identify fault characteristics using wavelets a procedure to adjust resolution of the mother wavelet is presented in detail. Experiments are conducted to obtain the run-up data of a rotor bearing setup for diagnosis of shaft misalignment and rotor stator rubbing faults.

  9. Experimental laboratory system to generate high frequency test environments

    SciTech Connect

    Gregory, D.L.; Paez, T.L.

    1991-01-01

    This is an extension of two previous analytical studies to investigate a technique for generating high frequency, high amplitude vibration environments. These environments are created using a device attached to a common vibration exciter that permits multiple metal on metal impacts driving a test surface. These analytical studies predicted that test environments with an energy content exceeding 10 kHz could be achieved using sinusoidal and random shaker excitations. The analysis predicted that chaotic vibrations yielding random like test environments could be generated from sinusoidal inputs. In this study, a much simplified version of the proposed system was fabricated and tested in the laboratory. Experimental measurements demonstrate that even this simplified system, utilizing a single impacting object, can generate environments on the test surface with significant frequency content in excess of 40 kHz. Results for sinusoidal shaker inputs tuned to create chaotic impact response are shown along with the responses due to random vibration shaker inputs. The experiments and results are discussed. 4 refs., 5 figs.

  10. Synergistic effects of high-frequency ultrasound on photocatalytic degradation of aldehydes and their intermediates using TiO2 suspension in water.

    PubMed

    Sekiguchi, Kazuhiko; Sasaki, Chie; Sakamoto, Kazuhiko

    2011-01-01

    The degradation of model substances, benzaldehyde (C(6)H(5)CHO) and formaldehyde (HCHO), were investigated under various conditions, namely, ultrasound (US) irradiation, TiO(2) photocatalysis with UV irradiation (UV/TiO(2)), and the combination of sonophotocatalysis and UV irradiation (US/UV/TiO(2)), in order to clarify the synergistic effects between US and UV/TiO(2). US and UV/TiO(2) primarily contribute to the degradation of highly hydrophobic and hydrophilic substances, respectively. However, the degradation rate was found to depend on the chemical properties and concentration of not only the substances initially present, but also their decomposition intermediates. Here, the essential information for accurately evaluating the synergistic effects on reaction rate under US/UV/TiO(2) conditions is reported, with a focus on the behavior of decomposition intermediates. PMID:20483201

  11. Low Frequency Radio-wave System for subsurface investigation

    NASA Astrophysics Data System (ADS)

    Soldovieri, Francesco; Gennarelli, Gianluca; Kudelya, Anatoliy; Denisov, Alexander

    2015-04-01

    Low frequency radio-wave methods (RWM) allow subsurface investigations in terms of lithological structure characterization, detection of filtration flows of ground water, anthropogenic and natural cavities. In this contribution, we present a RWM that exploits two coils working at frequencies of few MHz as transmitting and receiving antennas. The basic principle of this inductive method is as follows. The primary alternating electromagnetic field radiated by the transmitting coil induces eddy currents in the subsurface mainly due to the conductivity anomalies. These eddy currents generate a secondary (scattered) magnetic field which overlaps to the incident magnetic field and is detected by the receiving coil. Despite the simple operation of the system, the complexity of the electromagnetic scattering phenomenon at hand must be properly modeled to achieve adequate performance. Therefore, an advanced data processing technique, belonging to the class of the inverse scattering approaches, has been developed by the authors in a full 3D geometry. The proposed method allows to deal with data collected on a scanning surface under a dipole inductive profiling (DIP) modality, where the transmitting/receiving coils are moved simultaneously with fixed offset (multi-bistatic configuration). The hardware, called Dipole Inductive Radio-wave System (DIRS), is composed by an electronic unit and transmitting and receiving loop antennas radiating at frequencies of few MHz (2-4 MHz), which are installed on theodolite supports. The compactness of DIRS and its robustness to external electromagnetic interference offers the possibility to perform geophysical research up to the depth of some tens of meters and under several types of ground and water surfaces, vegetation, and weather conditions. The light weight and small size of system (the single antenna with support weights about 5 kg and has a diameter of 0.5m) allows two operators to perform geophysical research without disturbing the

  12. Design of variable frequency endoscope ultrasonic digital imaging system

    NASA Astrophysics Data System (ADS)

    Li, Ya-nan; Bai, Bao-ping; Chen, Xiao-dong; Zhao, Qiang; Deng, Hao-ran; Wang, Yi; Yu, Dao-yin

    2013-12-01

    This paper presented a real-time endoscope ultrasonic digital imaging system, which was based on FPGA and applied for gastrointestinal examination. Four modules, scan-line data processing module, coordinate transformation and interpolation algorithm module, cache reading and writing control module and transmitting and receiving control module were included in this FPGA based system. Through adopting different frequency ultrasound probes in a single insertion of endoscope, the system showed a high speed data processing mechanism capable of achieving images with various display effects. A high-precision modified coordinate calibration CORDIC (HMCC-CORDIC) algorithm was employed to realize coordinate transformation and interpolation simultaneously, while the precision and reliability of the algorithm could be greatly improved through utilizing the pipeline structure based on temporal logic. Also, system real-time control by computer could be achieved through operating under the condition of USB2.0 interface. The corresponding experimental validations proved the feasibility and the correctness of the proper data processing mechanism, the HMCC-CORDIC algorithm and the USB real-time control. Finally, the specific experimental sample, a tissue mimicking phantom, was imaged in real-time (25 frames per second) by an endoscope ultrasonic imaging system with image size 1024×1024. The requirements for clinical examination could be well satisfied with the imaging parameters discussed above.

  13. High Frequency Mechanical Pyroshock Simulations for Payload Systems

    SciTech Connect

    BATEMAN,VESTA I.; BROWN,FREDERICK A.; CAP,JEROME S.; NUSSER,MICHAEL A.

    1999-12-15

    Sandia National Laboratories (SNL) designs mechanical systems with components that must survive high frequency shock environments including pyrotechnic shock. These environments have not been simulated very well in the past at the payload system level because of weight limitations of traditional pyroshock mechanical simulations using resonant beams and plates. A new concept utilizing tuned resonators attached to the payload system and driven with the impact of an airgun projectile allow these simulations to be performed in the laboratory with high precision and repeatability without the use of explosives. A tuned resonator has been designed and constructed for a particular payload system. Comparison of laboratory responses with measurements made at the component locations during actual pyrotechnic events show excellent agreement for a bandwidth of DC to 4 kHz. The bases of comparison are shock spectra. This simple concept applies the mechanical pyroshock simulation simultaneously to all components with the correct boundary conditions in the payload system and is a considerable improvement over previous experimental techniques and simulations.

  14. Transmissivity and water quality of water-producing zones in the intermediate aquifer system, Sarasota County, Florida

    USGS Publications Warehouse

    Knochenmus, L.A.; Bowman, Geronia

    1998-01-01

    The intermediate aquifer system is an important water source in Sarasota County, Florida, because the quality of water in it is usually better than that in the underlying Upper Floridan aquifer. The intermediate aquifer system consists of a group of up to three water-producing zones separated by less-permeable units that restrict the vertical movement of ground water between zones. The diverse lithology, that makes up the intermediate aquifer system, reflects the variety of depositional environments that occurred during the late Oligocene and Miocene epochs. Slight changes in the depositional environment resulted in aquifer heterogeneity, creating both localized connection between water-producing zones and abrupt culmination of water-producing zones that are not well documented. Aquifer heterogeneity results in vertical and areal variability in hydraulic and water-quality properties. The uppermost water-producing zone is designated producing zone 1 but is not extensively used because of its limited production capability and limited areal extent. The second water-producing zone is designated producing zone 2, and most of the domestic- and irrigation-supply wells in the area are open to this zone. Additionally, producing zone 2 is utilized for public supply in southern coastal areas of Sarasota County. Producing zone 3 is the lowermost and most productive water-producing zone in the intermediate aquifer system. Public-supply well fields serving the cities of Sarasota and Venice, as well as the Plantation and Mabry Carlton Reserve well fields, utilize producing zone 3. Heads within the intermediate aquifer system generally increase with aquifer depth. However, localized head-gradient reversals occur in the study area, coinciding with sites of intense ground-water withdrawals. Heads in producing zones 1, 2, and 3 range from 1 to 23, 0.2 to 34, and 7 to 42 feet above sea level, respectively. Generally, an upward head gradient exists between producing zones 3 and 2

  15. COOL-IT: A HEAT EXCHANGER SYSTEM TO PROVIDE GASEOUS HELIUM AT INTERMEDIATE TEMPERATURES FOR SRF LINAC

    SciTech Connect

    Pattalwar, S. M.; Bate, R.

    2010-04-09

    ALICE, a prototype accelerator developed at the Daresbury laboratory UK, has successfully demonstrated the energy-recovery technique by circulating the electron beam to more than 20 MeV. At the heart of ALICE is a superconducting linac operating at 2 K. At high average-current operation the performance of Superconducting RF (SRF) cavities suffer from instabilities due to the generation of higher-order modes (HOM) as well as microphonics. HOMs are extracted out of the cavities using HOM absorbers operating at 80 K. This, however, increases the demand for cooling power at intermediate temperatures, i.e. at 80 K and 5 K, by more than an order of magnitude.In order to provide this extra cooling capacity with gaseous helium a new cryogenic system, 'COOL-IT,'(System for cooling to intermediate temperatures) is being developed. It will provide two streams of helium gases at 80 K and 5 K. COOL-IT uses a set of heat exchangers cooled by liquid helium and liquid nitrogen to generate two cold streams. It will be integrated into the existing cryo-system for ALICE for automatic operation. This paper describes the COOL-IT system in detail.

  16. [Effect of tricarboxylic acid cycle intermediates on nitric oxide system during acute hypoxia].

    PubMed

    Kurhaliuk, N M

    2002-01-01

    Effects Crebs Cycle of exogenous intermediates sodium succinate (50 mg/kg) and sodium alpha-ketoglutarate (200 mg/kg) on processes of mitochondrial ADP-stimulated respiration (using as substrates of oxidation 0.35 mM succinate, 1 mM alpha-ketoglutarate), production of nitric oxide under NO2-, NO3-, as well as carbamide, putrescyne content and processes of lipid peroxidation in the rats liver under acute hypoxia (7% O2 in N2, 30 min) have been studied. It was shown, that the exogenous sodium alpha-ketoglutarate increases nitric oxide content, aminotransferase activation, inhibition of succinatedehydrogenase simultaneously more than exogenous sodium succinate. It correlates with decreasing of processes lipid peroxidation in liver. PMID:14964867

  17. Relationships Between the Performance of Time/Frequency Standards and Navigation/Communication Systems

    NASA Technical Reports Server (NTRS)

    Hellwig, H.; Stein, S. R.; Walls, F. L.; Kahan, A.

    1978-01-01

    The relationship between system performance and clock or oscillator performance is discussed. Tradeoffs discussed include: short term stability versus bandwidth requirements; frequency accuracy versus signal acquisition time; flicker of frequency and drift versus resynchronization time; frequency precision versus communications traffic volume; spectral purity versus bit error rate, and frequency standard stability versus frequency selection and adjustability. The benefits and tradeoffs of using precise frequency and time signals are various levels of precision and accuracy are emphasized.

  18. Ion optics system incorporating radio frequency mass separation

    NASA Technical Reports Server (NTRS)

    Anderson, John R.; Carruth, M. R., Jr.

    1990-01-01

    Results of an experimental study are presented. They show that an RF mass discriminator, based on a Bennett mass spectrometer concept, can be used to discriminate between two species of ions with about a 2-to-1 charge-to-mass ratio. Such a device would be useful for separating monatomic and diatomic oxygen ions in a system designed to simulate the environment that spacecraft encounter in low earth orbit. The influence of changing mass discriminator parameters - such as the spacing of its grids, the amplitude and frequency of RF voltage signals applied to it and the current density of ions incident upon it - on its species discrimination capabilities is discussed. Experimental results are also compared to the results of a simple theoretical model to gain insight into the processes occurring in the discriminator. These results are shown to be in good agreement.

  19. Multi-frequency periodic vibration suppressing in active magnetic bearing-rotor systems via response matching in frequency domain

    NASA Astrophysics Data System (ADS)

    Jiang, Kejian; Zhu, Changsheng

    2011-05-01

    A method for multi-frequency periodic vibration suppressing in active magnetic bearing (AMB)-rotor systems is proposed, which is based on an adaptive finite-duration impulse response (FIR) filter in time domain. Firstly, the theoretic feasibility of the method is proved. However, two problems would be unavoidable, if the conventional adaptive FIR filter is adopted in practical application. One is that the convergence rate of the different frequency components may be highly disparate in multi-frequency vibration control. The other is that the computational complexity is significantly increased because the long memory FIR filter is required to match the transient response time of the AMB-rotor system. To overcome the problems above, the Fast Block Least Mean Square (FBLMS) algorithm is adopted to efficiently implement the computation in frequency domain at a computational cost far less than that of the conventional FIR filter. By the FBLMS algorithm, regardless of the number of the considered frequency components in vibration disturbance, the computational complexity would be invariable. Moreover, filter's weights in the FBLMS algorithm have the intuitional relation with signal's frequency. As a result, the convergence rate of each frequency component can be adjusted by assigning the individual step size parameter for each weight. Experiments with the reciprocating simulating disturbance test and the rotating harmonic vibration test were carried out on an AMB-rigid rotor test rig with a vertical shaft. The experiment results indicate that the proposed method with the FBLMS algorithm can achieve the good effectiveness for suppressing the multi-frequency vibration. The convergence property of each frequency component can be adjusted conveniently. Each harmonic component of the vibration can be addressed, respectively, by reconfiguring the frequency components of the reference input signal.

  20. Construction of the combined system of literature, intermediate data, and data in upper atmospheric research field

    NASA Astrophysics Data System (ADS)

    Koyama, Y.; Nose, M.; Iyemori, T.; Murayama, Y.; Kurakawa, K.; Abe, S.; Ikeda, D.; Tanaka, Y.; Umemura, N.; Shinbori, A.; Ueno, S.; Yagi, M.; Sato, Y.

    2014-12-01

    To investigate the mechanism of long-term variations in the upper atmosphere, we need to create integrated links between a variety of ground-based observations made at various locations from the equator to the poles because what we observe is the result of complicated processes. However, the Japanese observational databases (e.g., by a global network of radars, magnetometers, and optical sensors) have been maintained and made available to the community by each institution that conducted the observations. Then researchers encountered the problem that is difficult to look for various kinds of observational data to clarify the global scale physical phenomena. In order to solve the problem, the Japanese IUGONET project built the metadata database for upper atmosphere to cross-search their databases and integrated analysis tools. It became easy to find data and to derive many data to intermediate data by using above mentioned infrastructure. However, it is still difficult to reproduce the past research from the paper as only key because of lack of supplementary information. We introduce our activity to solve above mentioned problem especially about data publication which mints DOI and metadata to dataset by the Japanese local community relevant to upper atmospheric research field. In order to beyond data publication and citation, we describe our challenge to cooperation of literature, data, identifiers, general metadata, domain specific metadata, derivation process, and code.

  1. The Radio Frequency Health Node Wireless Sensor System

    NASA Technical Reports Server (NTRS)

    Valencia, J. Emilio; Stanley, Priscilla C.; Mackey, Paul J.

    2009-01-01

    The Radio Frequency Health Node (RFHN) wireless sensor system differs from other wireless sensor systems in ways originally intended to enhance utility as an instrumentation system for a spacecraft. The RFHN can also be adapted to use in terrestrial applications in which there are requirements for operational flexibility and integrability into higher-level instrumentation and data acquisition systems. As shown in the figure, the heart of the system is the RFHN, which is a unit that passes commands and data between (1) one or more commercially available wireless sensor units (optionally, also including wired sensor units) and (2) command and data interfaces with a local control computer that may be part of the spacecraft or other engineering system in which the wireless sensor system is installed. In turn, the local control computer can be in radio or wire communication with a remote control computer that may be part of a higher-level system. The remote control computer, acting via the local control computer and the RFHN, cannot only monitor readout data from the sensor units but can also remotely configure (program or reprogram) the RFHN and the sensor units during operation. In a spacecraft application, the RFHN and the sensor units can also be configured more nearly directly, prior to launch, via a serial interface that includes an umbilical cable between the spacecraft and ground support equipment. In either case, the RFHN wireless sensor system has the flexibility to be configured, as required, with different numbers and types of sensors for different applications. The RFHN can be used to effect realtime transfer of data from, and commands to, the wireless sensor units. It can also store data for later retrieval by an external computer. The RFHN communicates with the wireless sensor units via a radio transceiver module. The modular design of the RFHN makes it possible to add radio transceiver modules as needed to accommodate additional sets of wireless sensor

  2. Method of detecting system function by measuring frequency response

    DOEpatents

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.

    2012-04-03

    Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. The time profile of this signal has a duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time record by rectifying relative to the sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.

  3. Method of detecting system function by measuring frequency response

    DOEpatents

    Morrison, John L.; Morrison, William H.; Christophersen, Jon P.; Motloch, Chester G.

    2013-01-08

    Methods of rapidly measuring an impedance spectrum of an energy storage device in-situ over a limited number of logarithmically distributed frequencies are described. An energy storage device is excited with a known input signal, and a response is measured to ascertain the impedance spectrum. An excitation signal is a limited time duration sum-of-sines consisting of a select number of frequencies. In one embodiment, magnitude and phase of each frequency of interest within the sum-of-sines is identified when the selected frequencies and sample rate are logarithmic integer steps greater than two. This technique requires a measurement with a duration of one period of the lowest frequency. In another embodiment, where selected frequencies are distributed in octave steps, the impedance spectrum can be determined using a captured time record that is reduced to a half-period of the lowest frequency.

  4. Method of detecting system function by measuring frequency response

    NASA Technical Reports Server (NTRS)

    Morrison, John L. (Inventor); Morrison, William H. (Inventor); Christophersen, Jon P. (Inventor)

    2012-01-01

    Real-time battery impedance spectrum is acquired using a one-time record. Fast Summation Transformation (FST) is a parallel method of acquiring a real-time battery impedance spectrum using a one-time record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. The time profile of this signal has a duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time record by rectifying relative to the sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency.

  5. Frequency Stabilization of High-Power 3.3 μm CW Laser with a Frequency Comb System

    NASA Astrophysics Data System (ADS)

    Kuma, Susumu; Momose, Takamasa

    2010-06-01

    %TEXT OF YOUR ABSTRACT The development of optical frequency combs has enabled a broad range of lasers to be stabilized. In this study, we have developed a system to stabilize high-power CW mid-infrared (MIR) radiation at 3.3 μm using a NIR-VIS frequency comb. The mid-infrared radiation at 3.3 μm were generated as an idler of a CW OPO laser pumped by a 1.064 μm fibre laser. To stabilize the MIR radiation with a frequency comb system in 450 nm to 1.25 μm range, the pump frequency at 1.064 μm and the sum frequency of the MIR radiation and the pump radiation were locked simultaneously to the comb laser. The sum frequency of the MIR and pump radiations was generated in a PPLN crystal. With this technique, we have successfully obtained a width of better than 50 kHz at 3.3 μm with a power of more than 1 W. The stability is currently limited by the response of the PZT in an OPO cavity. Further improvement is underway. The stabilized MIR radiation at 3.3 μm can be used as a source for ultra-high-resolution spectroscopy of vibration-rotation transitions of molecules. Especially, it may be used to decrease the frequency uncertainty of the ν_3 F_2(2) component of the P(7) transition of CH_4, which is one of the optical frequency standards recommended by CIPM. Another application of frequency stabilized MIR radiation is to build-up MIR radiation in a cavity for optical manipulation and trapping of cold molecules we have proposed in New. J. Phys. 11. 055023 (2009).

  6. Polarization sensitive optical frequency domain imaging system for endobronchial imaging.

    PubMed

    Li, Jianan; Feroldi, Fabio; de Lange, Joop; Daniels, Johannes M A; Grünberg, Katrien; de Boer, Johannes F

    2015-02-01

    A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2x2 field matrix. A Jones matrix of the sample is derived and the sample birefringence is extracted by eigenvalue decomposition. The condition of balanced detection and the polarization mode dispersion are quantified. A complex field averaging method based on the alignment of randomly pointing field phasors is developed to reduce speckle noise. The variation of the polarization states incident on the tissue due to the circular scanning and catheter sheath birefringence is investigated. With this system we demonstrated imaging of ex vivo chicken muscle, in vivo pig lung and ex vivo human lung specimens. PMID:25836196

  7. Implementation of Treatment Systems for Low and Intermediate Radioactive Waste at Site Radwaste Treatment Facility (SRTF), PR China - 12556

    SciTech Connect

    Lohmann, Peter; Nasarek, Ralph; Aign, Joerg

    2012-07-01

    The AP1000 reactors being built in the People's Republic of China require a waste treatment facility to process the low and intermediate radioactive waste produced by these nuclear power stations. Westinghouse Electric Germany GmbH was successful in being awarded a contract as to the planning, delivery and commissioning of such a waste treatment facility. The Site Radwaste Treatment Facility (SRTF) is a waste treatment facility that can meet the AP1000 requirements and it will become operational in the near future. The SRTF is situated at the location of Sanmen, People's Republic of China, next to one of the AP1000 and is an adherent building to the AP1000 comprising different waste treatment processes for radioactive spent filter cartridges, ion-exchange resins and radioactive liquid and solid waste. The final product of the SRTF-treatment is a 200 l drum with cemented waste or grouted waste packages for storage in a local storage facility. The systems used in the SRTF are developed for these special requirements, based on experience from similar systems in the German nuclear industry. The main waste treatment systems in the SRTF are: - Filter Cartridge Processing System (FCS); - HVAC-Filter and Solid Waste Treatment Systems (HVS); - Chemical Liquid Treatment Systems (CTS); - Spent Resin Processing Systems (RES); - Mobile Treatment System (MBS). (authors)

  8. Glial cytoarchitecture in the central nervous system of the soft-shell turtle, Trionyx sinensis, revealed by intermediate filament immunohistochemistry.

    PubMed

    Lazzari, Maurizio; Franceschini, Valeria

    2006-10-01

    The distribution of the intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, has been studied in the central nervous system (CNS) of the soft-shell turtle (Trionyx sinensis) with immunoperoxidase histochemistry. GFAP immunohistochemistry pointed out the presence of different astroglial cell types. The brain pattern consists of ependymal radial glia whose cell bodies are located in the ependymal layer throughout the brain ventricular system. In the spinal cord, the ependyma is immunonegative, whereas positive radial astrocyte cell bodies are displaced from the ependyma into the periependymal position. Star-shaped astrocytes are observed only in the posterior intumescence of the spinal cord. The different regions of the CNS show a different intensity in GFAP immunostaining even in the same cellular type. Vimentin-immunoreactive structures are absent in the brain and spinal cord. The present study reports an heterogeneous feature of the astroglial pattern in the spinal cord compared to the brain which shows an ancestral condition. PMID:16763812

  9. Examining Low Frequency Molecular Modulations from the High Frequency Vantage Point: Anharmonically-Coupled Low Frequency Modes in PCET Model Systems

    NASA Astrophysics Data System (ADS)

    Reynolds, Anthony

    Proton-coupled electron transfer model systems (PCET) are examined using polarization selective femtosecond infrared pump-probe spectroscopy to determine how the structural modes are coupled to the OH/OD stretching vibrational mode by monitoring low frequency oscillations in the OH/OD vibrational mode using pump-probe techniques. For all of the systems discussed in this dissertation, low frequency modes are anharmonically coupled to the OH/OD stretching vibration. The OH/OD stretching vibration discussed in this dissertation have complex and broad lineshapes in the infrared region (IR) that are difficult to decipher. A broadband IR (BBIR) source, when used as part of a third order nonlinear infrared pump-probe spectroscopy, gains access into the electronic ground state potential energy surface. This information reveals the molecular dynamics that give rise to the complex structure in an IR spectra. The BBIR used for these experiments is generated by focusing 800 nm/400 nm pulses into compressed air and is tunable from 2 -- 5 microns with a FWHM greater than 1200 wavenumbers. The BBIR is a crucial mid-IR source in subsequent chapters for examining the broad lineshapes of the OH/OD stretching mode, which often exceeds 200 wavenumbers. The coupling of low frequency structural modulations to hydrogen bonding dynamics in PCET systems is explored by using the OH/OD stretching vibration in CCl4 or CHCl3. Third order nonlinear ultrafast infrared pump-probe spectroscopy is used to gather information on the high frequency OH/OD stretching vibrational modes in the ground state such as vibrational relaxation time and anharmonic vibrational coupling to low frequency structural modulations. At least one anharmonically coupled low frequency mode between 120 and 250 wavenumbers has been observed in all systems. To better understand and visualize how the low frequency mode may contribute to the PCET chemistry, we calculated the fundamental frequencies and third order coupling

  10. Design of Pound-Drever-Hall laser frequency stabilization system without phase shifter

    NASA Astrophysics Data System (ADS)

    Su, Juan; Jiao, Mingxing; Xing, Junhong; Li, Zhe

    2015-02-01

    The Pound-Drever-Hall (PDH) laser frequency stabilization is a wide spread adopted technique for narrow linewidth and ultra-stable lasers, and a phase shifter is an important part in a traditional PDH frequency stabilization system. A PDH laser frequency stabilization system without phase shifter was proposed, in which quadrature coherent detection method was used to extract the frequency drifts. Orthogonal reference signals are generated using direct digital frequency synthesizer (DDS) and mixed with the output of a photo-detector. Over-sampling technique and cumulative average algorithm were used to improve the detection resolution and SNR, orthogonal phase sensitive detection algorithm was adopted to obtain the frequency drifts. Both the quadrature demodulation system structure and the signal processing methods were adopted, the systematic detection error is reduced, the anti-noise performance is raised and long term frequency stability is improved with the PDH laser frequency stabilization system without phase shifter.

  11. All optical up-converted signal generation with high dispersion tolerance using frequency quadrupling technique for radio over fiber system

    NASA Astrophysics Data System (ADS)

    Gu, Yiying; Zhao, Jiayi; Hu, Jingjing; Kang, Zijian; Zhu, Wenwu; Fan, Feng; Han, Xiuyou; Zhao, Mingshan

    2016-05-01

    A novel all optical up-converted signal generation scheme with optical single-sideband (OSSB) technique for radio over fiber (RoF) application is presented and experimentally demonstrated using low-bandwidth devices. The OSSB signal is generated by one low-bandwidth intensity LiNbO3 Mach-Zehnder modulator (LN-MZM) under frequency quadrupling modulation scheme and one low-bandwidth LN-MZM under double sideband carrier suppressed modulation (DSB-CS) scheme. The proposed all OSSB generation scheme is capable of high tolerance of fiber chromatic dispersion induced power fading (DIPF) effect. Benefiting from this novel OSSB generation scheme, a 26 GHz radio frequency (RF) signal up-conversion is realized successfully when one sideband of the optical LO signal is reused as the optical carrier for intermediate frequency (IF) signal modulation. The received vector signal transmission over long distance single-mode fiber (SMF) shows negligible DIPF effect with the error vector magnitude (EVM) of 15.7% rms. In addition, a spurious free dynamic range (SFDR) of the OSSB up-converting system is measured up to 81 dB Hz2/3. The experiment results indicate that the proposed system may find potential applications in future wireless communication networks, especially in microcellular personal communication system (MPCS).

  12. Carbon transport in a bimetallic sodium loop simulating the intermediate heat transport system of a liquid metal fast breeder reactor

    SciTech Connect

    Hampton, L.V.; Spalaris, C.N.; Roy, P.

    1980-04-01

    Carbon transport data from a bimetallic sodium loop simulating the intermediate heat transport system of a Liquid Metal Fast Breeder Reactor are discussed. The results of bulk carbon analyses after 15,000 hours' exposure indicate a pattern of carburization of Type 304 stainless steel foils which is independent of loop sodium temperature. A model based on carbon activity gradients accounting for this behavior is proposed. Data also indicate that carburization of Type 304 stainless steel is a diffusion-controlled process; however, decarburization of the ferritic 2 1/4 Cr-1Mo steel is not. It is proposed that the decarburization of the ferritic steel is controlled by the dissolution of carbides in the steel matrix. The differences in the sodium decarburization behavior of electroslag remelted and vacuum-arc remelted 2 1/4 Cr-1Mo steel are also highlighted.

  13. Development of Thermal Barrier Coating System with Superior Thermal Cyclic Properties with an Intermediate Layer Containing MoSi2

    NASA Astrophysics Data System (ADS)

    Sonoya, Keiji; Tobe, Shogo

    The authors have developed a method of improving the thermal cyclic resistance of the thermal barrier coating system that is deposited on gas turbine components. A conventional thermal barrier coating consists of a duplex system: a top coating and a bond coating. The developed system has a protective intermediate layer of MoSi2 which prevents oxidation of the bond coating. The conventional duplex plasma -sprayed coating was delaminated after 20 thermal cycles. On the other hand, the developed triple-layered coating system was not delaminated after 60 cycles. The reason for the enhanced resistance to thermal cycles of the developed triple-layered coating system is that the MoSi2 layer between the top coating and the bond coating has a self-repairing property. MoSi2 oxidizes to form SiO2, which seals the cracks and pores formed between the top coating and the bond coating. Thus, the formation of a thermally grown oxide(TGO), which causes the delamination of the coating, is prevented and the thermal cyclic resistance is improved.

  14. Ternary polyplex micelles with PEG shells and intermediate barrier to complexed DNA cores for efficient systemic gene delivery.

    PubMed

    Li, Junjie; Chen, Qixian; Zha, Zengshi; Li, Hui; Toh, Kazuko; Dirisala, Anjaneyulu; Matsumoto, Yu; Osada, Kensuke; Kataoka, Kazunori; Ge, Zhishen

    2015-07-10

    Simultaneous achievement of prolonged retention in blood circulation and efficient gene transfection activity in target tissues has always been a major challenge hindering in vivo applications of nonviral gene vectors via systemic administration. Herein, we constructed novel rod-shaped ternary polyplex micelles (TPMs) via complexation between the mixed block copolymers of poly(ethylene glycol)-b-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (PEG-b-PAsp(DET)) and poly(N-isopropylacrylamide)-b-PAsp(DET) (PNIPAM-b-PAsp(DET)) and plasmid DNA (pDNA) at room temperature, exhibiting distinct temperature-responsive formation of a hydrophobic intermediate layer between PEG shells and pDNA cores through facile temperature increase from room temperature to body temperature (~37 °C). As compared with binary polyplex micelles of PEG-b-PAsp(DET) (BPMs), TPMs were confirmed to condense pDNA into a more compact structure, which achieved enhanced tolerability to nuclease digestion and strong counter polyanion exchange. In vitro gene transfection results demonstrated TPMs exhibiting enhanced gene transfection efficiency due to efficient cellular uptake and endosomal escape. Moreover, in vivo performance evaluation after intravenous injection confirmed that TPMs achieved significantly prolonged blood circulation, high tumor accumulation, and promoted gene expression in tumor tissue. Moreover, TPMs loading therapeutic pDNA encoding an anti-angiogenic protein remarkably suppressed tumor growth following intravenous injection into H22 tumor-bearing mice. These results suggest TPMs with PEG shells and facilely engineered intermediate barrier to inner complexed pDNA have great potentials as systemic nonviral gene vectors for cancer gene therapy. PMID:25912408

  15. Systems and methods for determining radio frequency interference

    NASA Technical Reports Server (NTRS)

    Johannsen, K. G.; Sabaroff, S.; Henry, V. F. (Inventor)

    1978-01-01

    The presence, frequency and amplitude of radio frequency interference superimposed on communication links originating from a terrestrial region and including a relay in a geostationary spacecraft are determined by pointing a narrow beam antenna on the satellite at the terrestrial region. The level of noise radiated from the region to the antenna is measured at a terrestrial station that is usually remote from the region. Calibrating radio signals having a plurality of predetermined EIRP's (Effective Isotropic Radiated Power) and frequencies in the spectrum are transmitted from the region through the spacecraft narrow beam antenna back to the station. At the station, the levels of the received calibrating signals are separately measured for each of the frequency bands and EIRP's.

  16. Spatial and frequency averaging techniques for a polarimetric scatterometer system

    SciTech Connect

    Monakov, A.A.; Stjernman, A.S.; Nystroem, A.K. ); Vivekanandan, J. )

    1994-01-01

    An accurate estimation of backscattering coefficients for various types of rough surfaces is the main theme of remote sensing. Radar scattering signals from distributed targets exhibit fading due to interference associated with coherent scattering from individual scatterers within the resolution volume. Uncertainty in radar measurements which arises as a result of fading is reduced by averaging independent samples. Independent samples are obtained by collecting the radar returns from nonoverlapping footprints (spatial averaging) and/or nonoverlapping frequencies (frequency agility techniques). An improved formulation of fading characteristics for the spatial averaging and frequency agility technique is derived by taking into account the rough surface scattering process. Kirchhoff's approximation is used to describe rough surface scattering. Expressions for fading decorrelation distance and decorrelation bandwidth are derived. Rough surface scattering measurements are performed between L and X bands. Measured frequency and spatial correlation coefficients show good agreement with theoretical results.

  17. Distributed Bragg reflector laser for frequency modulated communication systems

    SciTech Connect

    Chraplyvy, A.R.; Koch, T.L.; Tkach, R.W.

    1990-02-27

    This patent describes a lightwave transmitter. It includes a distributed Bragg reflector laser and means for frequency modulating said laser. The laser comprises first and second semiconductor heterostructure regions.

  18. Studies of ECCM improvements for frequency-hopping CPFSK systems

    NASA Astrophysics Data System (ADS)

    Lee, J. S.; Miller, L. E.; French, R. H.

    1990-05-01

    The performance of frequency hopping CPFSK modulations (such as used in several Army radio systems) in the presence of worst case partial band noise jamming (WCPBNJ) is derived for both limiter-discriminator and differential detector forms of receiver. The transmitter is assumed to repeat the data L times on different hops, and the receiver combines the L chips for each data symbol in a way to mitigate the effects of the jamming. Hard-decision combining simply makes a binary decision on each chip, then a majority decision on the whole symbol; this limits a jammed chip to one vote. AGC combining weights each analog chip sample in inverse proportion to the received noise power and decides on the basis of the sum of weighted chip samples; jammed chips tend to be weighted less. Analysis and computations show that either form of ECM combining can produce a 27 dB gain against WCPBNJ, and with error-control coding, a 31 to 33 dB gain. Coding alone can give a 28 to 29 dB gain. Soft decoding of hard-decision diversity combining gives 1.4 dB more gain than hard decoding. It is also shown that, due to the spectral attenuation characteristics of the receiver's IF filter, the effects of the transient phase difference between the incoming hopping waveform and the receiver's synthesizer are primarily confined to an interval of duration T + ts + tau, where T is the symbol duration (inverse of IF bandwidth), ts is the synthesizer switching time, and tau is the offset in synchronization between the received signal and the receiver's synthesizer.

  19. Design of digital Pound-Drever-Hall frequency stabilizing system for two-cavity dual-frequency Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Xing, Junhong; Jiao, Mingxing; Zheng, Yi; Zheng, Lingling

    2013-01-01

    Two-cavity dual-frequency Nd:YAG laser with large frequency difference can be used as an ideal light source for synthetic-wave absolute-distance interferometric system. The operation principle of the two-cavity dual-frequency Nd:YAG laser with large frequency difference has been introduced, and the frequency locking principle of the Pound-Drever-Hall (PDH) method has been analyzed. A FPGA-based digital PDH frequency stabilizing system for the two-cavity dual-frequency Nd:YAG laser has been designed, in which the same frequency reference of a high finesse Fabry-Perot cavity is used and two separate heterodyne interference sub-systems are employed so that two electrical error signals can be obtained. Having been processed through FPGA, the output signals are applied to drive the PZT frequency actuators attached on the two-cavity dual-frequency Nd:YAG laser, as a result both operating frequencies of the two-cavity dual-frequency Nd:YAG laser can be simultaneously frequency-locked to two resonant frequencies of the Fabry-Perot cavity. A frequency stability of better than 10-10 will be obtained by use of the digital PDH frequency locking system, which can meet the needs of synthetic-wave absolute-distance interferometry.

  20. Intermediate-Scale High-Solids Anaerobic Digestion System Operational Development

    SciTech Connect

    Rivard, C. J.

    1995-02-01

    Anaerobic bioconversion of solid organic wastes represents a disposal option in which two useful products may be produced, including a medium Btu fuel gas (biogas) and a compost-quality organic residue. The application of high-solids technology may offer several advantages over conventional low-solids digester technology. The National Renewable Energy Laboratory (NREL) has developed a unique digester system capable of uniformly mixing high-solids materials at low cost. During the first 1.5 years of operation, a variety of modifications and improvements were instituted to increase the safety, reliability, and performance of the system. Those improvements, which may be critical in further scale-up efforts using ,the NREL high-solids digester design are detailed in this report.

  1. Intermediate Energies for Nuclear Astrophysics and the Development of a Position Sensitive Microstrip Detector System

    SciTech Connect

    Sobotka, Lee G.; Blackmon, J.; Bertulani, C.

    2015-12-30

    The chemical elements are made at astrophysical sites through a sequence of nuclear reactions often involving unstable nuclei. The overarching aim of this project is to construct a system that allows for the inverse process of nucleosynthesis (i.e. breakup of heavier nuclei into lighter ones) to be studied in high efficiency. The specific problem to be overcome with this grant is inadequate dynamic range and (triggering) threshold to detect the products of the breakup which include both heavy ions (with large energy and large deposited energy in a detector system) and protons (with little energy and deposited energy.) Early on in the grant we provided both TAMU and RIKEN (the site of the eventual experiments) with working systems based on the existing technology. This technology could be used with either an external preamplifier that was to be designed and fabricated by our RIKEN collaborators or upgraded by replacing the existing chip with one we designed. The RIKEN external preamplifier project never can to completion but our revised chip was designed, fabricated, used in a test experiment and performs as required.

  2. A Protein Concentration Measurement System Using a Flexural Plate-Wave Frequency-Shift Readout Technique

    PubMed Central

    Wang, Chua-Chin; Sung, Tzu-Chiao; Hsu, Chia-Hao; Tsai, Yue-Da; Chen, Yun-Chi; Lee, Ming-Chih; Huang, I-Yu

    2013-01-01

    A protein concentration measurement system with two-port flexural plate-wave (FPW) biosensors using a frequency-shift readout technique is presented in this paper. The proposed frequency-shift readout method employs a peak detecting scheme to measure the amount of resonant frequency shift. The proposed system is composed of a linear frequency generator, a pair of peak detectors, two registers, and a subtractor. The frequency sweep range of the linear frequency generator is limited to 2 MHz to 10 MHz according to the characteristics of the FPW biosensors. The proposed frequency-shift readout circuit is carried out on silicon using a standard 0.18 μm CMOS technology. The sensitivity of the peak detectors is measured to be 10 mV. The power consumption of the proposed protein concentration measurement system is 48 mW given a 0.1 MHz system clock. PMID:23344375

  3. Astroglial cells in the central nervous system of the adult brown anole lizard, Anolis sagrei, revealed by intermediate filament immunohistochemistry.

    PubMed

    Lazzari, Maurizio; Franceschini, Valeria

    2005-09-01

    We analyzed the distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP), and vimentin in the brain and spinal cord of the adult brown anole lizard, Anolis sagrei. The GFAP immunoreactivity is strong and the positive structures are basically represented by fibers of different lengths and thicknesses which are arranged in a regular radial pattern throughout the central nervous system. In the brain regions that have a thicker neural wall, the radial orientation is not so evident as in the thinner areas. These fibers emerge from radial ependymoglia (tanycytes) whose cell bodies are generally GFAP-immunopositive. The glial fibers give rise to endfeet that are apposed to the subpial surface and to blood vessel walls. In the spinal cord, the optic tectum and the lateroventral regions of the mesencephalon and medulla oblongata, star-shaped astrocytes coexist with radial structures. Vimentin-immunoreactive structures are absent in the brain and spinal cord. In A. sagrei the immunohistochemical response of the astroglial intermediate filaments appears typical of a mature astroglial cell lineage, since they fundamentally express GFAP immunoreactivity. A Western-blot analysis reveals a GFAP-positive single band, common to the different nervous areas. This immunohistochemical study shows that the star-shaped astrocytes have a different distribution in saurians and while the glial pattern of A. sagrei is more evolved than in urodeles it remains immature as compared with crocodilians, avians, and mammals. This condition suggests that reptiles represent a fundamental step in the phylogenetic evolution of the vertebrate glial cells. PMID:16086399

  4. Intermediate Cambodian Reader.

    ERIC Educational Resources Information Center

    Huffman, Franklin E., Ed.; Proum, Im, Ed.

    This book is a sequel to the "Cambodian System of Writing and Beginning Reader." It is intended to serve as an intermediate reader to develop the student's ability to the point of reading Cambodian texts with the aid of a dictionary. Part One of the book consists of 37 readings, graded in length and difficulty, and selected to provide a wide range…

  5. Method of detecting system function by measuring frequency response

    DOEpatents

    Morrison, John L.; Morrison, William H.

    2008-07-01

    Real time battery impedance spectrum is acquired using one time record, Compensated Synchronous Detection (CSD). This parallel method enables battery diagnostics. The excitation current to a test battery is a sum of equal amplitude sin waves of a few frequencies spread over range of interest. The time profile of this signal has duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known, synchronous detection processes the time record and each component, both magnitude and phase, is obtained. For compensation, the components, except the one of interest, are reassembled in the time domain. The resulting signal is subtracted from the original signal and the component of interest is synchronously detected. This process is repeated for each component.

  6. Method of Detecting System Function by Measuring Frequency Response

    NASA Technical Reports Server (NTRS)

    Morrison, John L. (Inventor); Morrison, William H. (Inventor)

    2008-01-01

    Real time battery impedance spectrum is acquired using one time record, Compensated Synchronous Detection (CSD). This parallel method enables battery diagnostics. The excitation current to a test battery is a sum of equal amplitude sin waves of a few frequencies spread over range of interest. The time profile of this signal has duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known, synchronous detection processes the time record and each component, both magnitude and phase, is obtained. For compensation, the components, except the one of interest, are reassembled in the time domain. The resulting signal is subtracted from the original signal and the component of interest is synchronously detected. This process is repeated for each component.

  7. System for transmitting low frequency analog signals over AC power lines

    DOEpatents

    Baker, Steven P.; Durall, Robert L.; Haynes, Howard D.

    1989-09-05

    A system for transmitting low frequency analog signals over AC power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an AC power line. The modulation signal frequency range in selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the AC power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal.

  8. A system for tranmitting low frequency analog signals over ac power lines

    DOEpatents

    Baker, S.P.; Durall, R.L.; Haynes, H.D.

    1987-07-30

    A system for transmitting low frequency analog signals over ac power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an ac power line. The modulation signal frequency range is selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the ac power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal. 4 figs.

  9. System for transmitting low frequency analog signals over AC power lines

    DOEpatents

    Baker, Steven P.; Durall, Robert L.; Haynes, Howard D.

    1989-01-01

    A system for transmitting low frequency analog signals over AC power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an AC power line. The modulation signal frequency range in selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the AC power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal.

  10. Autonomous Rubidium Clock Weak Frequency Jump Detector for Onboard Navigation Satellite System.

    PubMed

    Khare, Akshay; Arora, Rajat; Banik, Alak; Mehta, Sanjay D

    2016-02-01

    Frequency jumps are common in rubidium frequency sources. They affect the estimation of user position in navigational satellite systems. These jumps must be detected and corrected immediately as they have direct impact on the navigation system integrity. A novel weak frequency jump detector is proposed based on a Kalman filter with a multi-interval approach. This detector can be applied for both "sudden" and "slow" frequency transitions. In this detection method, noises of clock data are reduced by Kalman filtering, for accurate estimation of jump size with less latency. Analysis on in-orbit rubidium atomic frequency standard (RAFS) phase telemetry data shows that the detector can be used for fast detection and correction of weak frequency jumps. Furthermore, performance comparison of different existing frequency jump detection techniques with the proposed detector is discussed. A multialgorithm-based strategy is proposed depending on the jump size and latency for onboard navigation satellites having RAFS as the primary frequency source. PMID:26685233