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Sample records for intermediate frequency system

  1. [Design of modulating intermediate frequency electrotherapy system based on microcontroller unit].

    PubMed

    Yu, Xuefei; Liu, Xianfeng; Peng, Daming

    2010-12-01

    This article is devoted to the design of a system for modulating intermediate frequency electrotherapy waveform output. Prescriptions with different output waveform combinations were produced using microcontroller unit (MCU). The rich output waveforms effectively improve tolerance of human adaptability and achieve a therapeutic effect.

  2. Digital low level rf control system with four different intermediate frequencies for the International Linear Collider

    NASA Astrophysics Data System (ADS)

    Wibowo, Sigit Basuki; Matsumoto, Toshihiro; Michizono, Shinichiro; Miura, Takako; Qiu, Feng; Liu, Na

    2017-09-01

    A field programmable gate array-based digital low level rf (LLRF) control system will be used in the International Linear Collider (ILC) in order to satisfy the rf stability requirements. The digital LLRF control system with four different intermediate frequencies has been developed to decrease the required number of analog-to-digital converters in this system. The proof of concept of this technique was demonstrated at the Superconducting RF Test Facility in the High Energy Accelerator Research Organization, Japan. The amplitude and phase stability has fulfilled the ILC requirements.

  3. [Design of low-intermediate frequency electrotherapy and pain assessment system].

    PubMed

    Liang, Chunyan; Tian, Xuelong; Yu, Xuehong; Luo, Hongyan

    2014-06-01

    Aiming at the single treatment and the design separation between treatment and assessment in electrotherapy equipment, a kind of system including low-intermediate frequency treatment and efficacy evaluation was developed. With C8051F020 single-chip microcomputer as the core and the circuit design and software programming used, the system realized the random switch of therapeutic parameters, the collection, display and data storage of pressure pain threshold in the assessment. Experiment results showed that the stimulus waveform, current intensity, frequency, duty ratio of the system output were adjustable, accurate and reliable. The obtained pressure pain threshold had a higher accuracy (< 0.3 N) and better stability, guiding the parameter choice in the precise electrical stimulation. It, therefore, provides a reliable technical support for the treatment and curative effect assessment.

  4. Occupational exposure to intermediate frequency and extremely low frequency magnetic fields among personnel working near electronic article surveillance systems.

    PubMed

    Roivainen, Päivi; Eskelinen, Tuomo; Jokela, Kari; Juutilainen, Jukka

    2014-05-01

    Cashiers are potentially exposed to intermediate frequency (IF) magnetic fields at their workplaces because of the electronic article surveillance (EAS) systems used in stores to protect merchandise against theft. This study aimed at investigating occupational exposure of cashiers to IF magnetic fields in Finnish stores. Exposure to extremely low frequency (ELF) magnetic fields was also evaluated because cashiers work near various devices operating with 50 Hz electric power. The peak magnetic flux density was measured for IF magnetic fields, and was found to vary from 0.2 to 4 µT at the cashier's seat. ELF magnetic fields from 0.03 to 4.5 µT were found at the cashier's seat. These values are much lower than exposure limits. However, according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) occupational reference levels for IF magnetic fields (141 µT for the peak field) were exceeded in some cases (maximum 189 µT) for short periods of time when cashiers walked through the EAS gates. As the ICNIRP reference levels do not define any minimum time for exposure, additional investigations are recommended to determine compliance with basic restrictions. Even if the basic restrictions are not exceeded, persons working near EAS devices represent an exceptional group of workers with respect to exposure to electromagnetic fields. This group could serve as a basis for epidemiological studies addressing possible health effects of IF magnetic fields. Compliance with the reference levels for IF fields was evaluated using both broadband measurement of peak fields and the ICNIRP summation rule for multiple frequencies. The latter was generally more conservative, and the difference between the two methods was large (>10-fold) for EAS systems using a 58 kHz signal with complex waveform. This indicates that the ICNIRP multiple frequency rule can be unnecessarily conservative when measuring complex waveforms. © 2014 Wiley Periodicals, Inc.

  5. Note: Stability control of intermediate frequencies of a three laser far-infrared polarimeter-interferometer system.

    PubMed

    Yu, Jiang-Tao; Li, He-Ping; Nie, Qiu-Yue; Zou, Zhi-Yong; Liu, Hai-Qing; Bao, Cheng-Yu; Jie, Yin-Xian; Li, Zhan-Xian

    2016-12-01

    Stability of the intermediate frequency (IF) in the far-infrared polarimeter-interferometer diagnostic system is critically important for the long pulse discharge experiments on the EAST tokamak. In this note, a real-time remote/local IF stability control system is described. The measured plasma parameters, including the Faraday rotation angle, electron density, lower hybrid wave, and plasma current, are obtained with the aid of this newly developed IF stability control system.

  6. Note: Stability control of intermediate frequencies of a three laser far-infrared polarimeter-interferometer system

    NASA Astrophysics Data System (ADS)

    Yu, Jiang-Tao; Li, He-Ping; Nie, Qiu-Yue; Zou, Zhi-Yong; Liu, Hai-Qing; Bao, Cheng-Yu; Jie, Yin-Xian; Li, Zhan-Xian

    2016-12-01

    Stability of the intermediate frequency (IF) in the far-infrared polarimeter-interferometer diagnostic system is critically important for the long pulse discharge experiments on the EAST tokamak. In this note, a real-time remote/local IF stability control system is described. The measured plasma parameters, including the Faraday rotation angle, electron density, lower hybrid wave, and plasma current, are obtained with the aid of this newly developed IF stability control system.

  7. 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.

  8. 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.

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

    PubMed

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

    2011-06-01

    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.

  10. 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.

  11. 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.

  12. Effects of 21-kHz intermediate frequency magnetic fields on blood properties and immune systems of juvenile rats.

    PubMed

    Ushiyama, Akira; Ohtani, Shin; Suzuki, Yukihisa; Wada, Keiji; Kunugita, Naoki; Ohkubo, Chiyoji

    2014-12-01

    Due to a lack of science-based evidence, we explored the effects of exposure to intermediate frequency magnetic fields (IF-MF) on experimental animals. We assessed several immunological parameters to determine the effect of exposure of the whole body to IF-MF. Male Sprague-Dawley rats (4-5 weeks old) were divided into three groups: Cage-control, sham, and 3.8-mT (rms) exposure groups. The animals were exposed to IF-MF at 21 kHz under fixed conditions in an acrylic holder. Exposure was performed for 1 h/day for 14 consecutive days. On the 15th day following the exposure, biochemical and hematological parameters in blood were analyzed. The effects of the exposure on immunological functions such as the cytotoxic activity of lymphocytes, chemotactic and phagocytic activity of granulocytes, and T (cluster of differentiation 4 [CD4] and cluster of differentiation 8 [CD8])-cell frequency were also examined. Hematological parameters were not affected by IF-MF exposure. Other immune functions such as the cytotoxic activity and phagocytic activity were not affected. Populations of T cells after exposure also did not show any significant differences. In blood biochemistry, there was significant difference in inorganic phosphorus level between sham and exposure group. However, this will not induce any pathophysiological status, because they were still within physiological range. Overall, no significant effect by exposure of IF-MF was observed under our experimental conditions. Our results suggest that exposure to 21-kHz sinusoidal IF-MF at 3.8 mT for 1 h/day for 14 days did not affect immune function in juvenile rats.

  13. Intermediate frequency magnetic field and chick embryotoxicity.

    PubMed

    Nishimura, Izumi; Tanaka, Keiko; Negishi, Tadashi

    2013-09-01

    Intermediate frequency magnetic fields (MFs) have widely been used in industrial machines and home appliances, such as induction heating cookers, although toxicity studies to evaluate the potential health risks of such fields are insufficient. In induction heating cookers, the MF source (i.e. hobs), is located near the abdominal position of a person cooking. Hence, developmental effects on the fetus may be a concern in case the person is a pregnant woman. Fertile White Leghorn eggs (60/group) were either exposed to 20 kHz, 1.1 mT(rms) or 60 kHz, 0.11 mT(rms) sinusoidal MFs for 19 days during embryogenesis. The same number of eggs served as a control group. In addition, a sham-sham experiment was conducted to validate the equality between exposure and control facilities. After exposure, embryos were examined for mortality rate and stage. Live embryos were evaluated for developmental stage and gross and skeletal anomalies. Length of upper beak and leg digits was also measured. Examinations were conducted in a blinded fashion to ensure quality assurance; experiments were triplicated for each frequency to confirm the outcome reproducibility. Mortality rate and stage, incidence of malformed embryos, and developmental variables in live embryos were found to be similar between the MF-exposed and corresponding control group. Incidence of gross anomalies such as mandibular edema and skeletal anomalies such as coccyx defects were low across the experiments, and no significant group differences were noted. In conclusion, exposure to 20 kHz or 60 kHz MF did not produce any significant teratogenic developmental effects in chick embryos.

  14. Radio frequency ablation of small renal tumors:: intermediate results.

    PubMed

    Hwang, J J; Walther, M M; Pautler, S E; Coleman, J A; Hvizda, J; Peterson, James; Linehan, W M; Wood, B J

    2004-05-01

    With evolving radio frequency technology, the clinical application of radio frequency ablation (RFA) has been actively investigated in the treatment for small renal tumors. We present our intermediate patient outcomes after RFA. Since January 2001, 17 patients with a total of 24 hereditary renal tumors ranging from 1.2 to 2.85 cm were treated with RFA using the 200 W Cool-tip RF System (Radionics, Burlington, Massachusetts) under laparoscopic (9) or percutaneous (8) guidance and had a minimum 1-year followup. A percutaneous approach was considered unsuitable if kidney tumors were contiguous to bowel, ureter or large vessels. Treatment eligibility criteria included an average tumor diameter of less than 3.0 cm, tumor growth during 1 year and solid appearance with contrast enhancement (HU change greater than 20) on computerized tomography (CT). Postoperative followup consisted of CT with and without intravenous contrast, and renal function assessment at regular intervals. Median patient age was 38 years (range 20 to 51). At a median followup of 385 days (range 342 to 691), median tumor or thermal lesion diameter decreased from 2.26 to 1.62 cm (p = 0.0013), and only 1 lesion (4%), which was located centrally near the hilum, exhibited contrast enhancement (HU change greater than 10) on CT at 12 months. Of the 15 renal tumors ablated laparoscopically, 13 were in direct contact with the bowel and 2 were abutting the ureter, necessitating mobilization before RFA. Laparoscopic ultrasound was used to guide radio frequency electrode placement and monitor the ablation process in these cases. Operative time and intraoperative blood loss (mean +/- standard mean of error) were 243 +/- 29 minutes and 67 +/- 9 cc, respectively. In 1 patient whose ureter was adherent to the tumor a ureteropelvic junction obstruction developed after laparoscopic RFA, requiring open repair. At the minimum 1-year followup 23 of 24 ablated tumors lacked contrast uptake on CT, meeting our radiographic

  15. RADIO FREQUENCY ABLATION OF SMALL RENAL TUMORS: INTERMEDIATE RESULTS

    PubMed Central

    HWANG, J. J.; WALTHER, M. M.; PAUTLER, S. E.; COLEMAN, J. A.; HVIZDA, J.; PETERSON, JAMES; LINEHAN, W. M.; WOOD, B. J.

    2008-01-01

    Purpose With evolving radio frequency technology, the clinical application of radio frequency ablation (RFA) has been actively investigated in the treatment for small renal tumors. We present our intermediate patient outcomes after RFA. Materials and Methods Since January 2001, 17 patients with a total of 24 hereditary renal tumors ranging from 1.2 to 2.85 cm were treated with RFA using the 200 W Cool-tip RF System (Radionics, Burlington, Massachusetts) under laparoscopic (9) or percutaneous (8) guidance and had a minimum 1-year followup. A percutaneous approach was considered unsuitable if kidney tumors were contiguous to bowel, ureter or large vessels. Treatment eligibility criteria included an average tumor diameter of less than 3.0 cm, tumor growth during 1 year and solid appearance with contrast enhancement (HU change greater than 20) on computerized tomography (CT). Postoperative followup consisted of CT with and without intravenous contrast, and renal function assessment at regular intervals. Results Median patient age was 38 years (range 20 to 51). At a median followup of 385 days (range 342 to 691), median tumor or thermal lesion diameter decreased from 2.26 to 1.62 cm (p = 0.0013), and only 1 lesion (4%), which was located centrally near the hilum, exhibited contrast enhancement (HU change greater than 10) on CT at 12 months. Of the 15 renal tumors ablated laparoscopically, 13 were in direct contact with the bowel and 2 were abutting the ureter, necessitating mobilization before RFA. Laparoscopic ultrasound was used to guide radio frequency electrode placement and monitor the ablation process in these cases. Operative time and intraoperative blood loss (mean ± standard mean of error) were 243 ± 29 minutes and 67 ± 9 cc, respectively. In 1 patient whose ureter was adherent to the tumor a ureteropelvic junction obstruction developed after laparoscopic RFA, requiring open repair. Conclusions At the minimum 1-year followup 23 of 24 ablated tumors lacked

  16. 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.

  17. 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.

  18. Hypermagnetic knots and gravitational radiation at intermediate frequencies

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2017-07-01

    The maximally gyrotropic configurations of the hypermagnetic field at the electroweak epoch can induce a stochastic background of relic gravitational waves with comoving frequencies ranging from the μHz to the kHz. Using two complementary approaches we construct a physical template family for the emission of the gravitational radiation produced by the hypermagnetic knots. The current constraints and the presumed sensitivities of the advanced wide-band interferometers (both terrestrial and space-borne) are combined to infer that the lack of observations at intermediate frequencies may invalidate the premise of baryogenesis models based (directly or indirectly) on the presence of gyrotropic configurations of the hypermagnetic field at the electroweak epoch. Over the intermediate frequency range the spectral energy density of the gravitational waves emitted by the hypermagnetic knots at the electroweak scale can exceed the inflationary signal even by nine orders of magnitude without affecting the standard bounds applicable on the stochastic backgrounds of gravitational radiation. The signal of hypermagnetic knots can be disambiguated, at least in principle, since the the produced gravitational waves are polarized.

  19. 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

  20. Digital intermediate frequency QAM modulator using parallel processing

    DOEpatents

    Pao, Hsueh-Yuan [Livermore, CA; Tran, Binh-Nien [San Ramon, CA

    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.

  1. Maximum species richness at intermediate frequencies of disturbance: consistency among levels of productivity.

    PubMed

    Svensson, J Robin; Lindegarth, Mats; Siccha, Michael; Lenz, Mark; Molis, Markus; Wahl, Martin; Pavia, Henrik

    2007-04-01

    Development of a mechanistic understanding and predictions of patterns of biodiversity is a central theme in ecology. One of the most influential theories, the intermediate disturbance hypothesis (IDH), predicts maximum diversity at intermediate levels of disturbance frequency. The dynamic equilibrium model (DEM), an extension of the IDH, predicts that the level of productivity determines at what frequency of disturbance maximum diversity occurs. To test, and contrast, the predictions of these two models, a field experiment on marine hard-substratum assemblages was conducted with seven levels of disturbance frequency and three levels of nutrient availability. Consistent with the IDH, maximum diversity, measured as species richness, was observed at an intermediate frequency of disturbance. Despite documented effects on productivity, the relationship between disturbance and diversity was not altered by the nutrient treatments. Thus, in this system the DEM did not improve the understanding of patterns of diversity compared to the IDH. Furthermore, it is suggested that careful consideration of measurements and practical definitions of productivity in natural assemblages is necessary for a rigorous test of the DEM.

  2. 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.

  3. Tunable frequency stabilization to Zeeman sublevel transitions between an intermediate state and Rydberg states

    NASA Astrophysics Data System (ADS)

    Bao, Shanxia; Zhang, Hao; Zhou, Jian; Zhang, Linjie; Zhao, Jianming; Xiao, Liantuan; Jia, Suotang

    2017-01-01

    We demonstrate a robust method of direct laser frequency locking on the Zeeman sublevel transitions between an intermediate state and Rydberg states, with continuously tunable frequency range from  -35 MHz to  +35 MHz, which is based on electromagnetically induced transparency (EIT) spectra of nondegenerate Zeeman sublevels in a Rydberg cascade system. With a small axial magnetic field, the EIT spectrum will split into two individual sub-peaks due to the Zeeman Effect of three energy levels, including the 133Cs 6S1/2, 6P3/2 and nl Rydberg states which form the cascade system. It is shown that the coupling field, corresponding to the transitions between the Zeeman sublevels of the intermediate state and Rydberg state, can be locked arbitrarily on any one of the two EIT sub-peaks. The frequency stability of locked lasers is bounded by 0.81 MHz. The root of Allan variance of the frequency reaches a minimum of 2.06× {{10}-8} for an averaging time of 512 s.

  4. Effect of intermediate-frequency vibrations on the probability of the elementary charge-tansfer act

    SciTech Connect

    Belousov, A.A.; Kuznetsov, A.M.

    1986-01-01

    The probability of nonadiabatic transitions can be calculated in the harmonic approximation for any sort of vibrational spectrum of a system from the quantum-mechanical theory of charge-transfer processes in condensed media as it exists today. For adiabatic transitions, the largest difficulties for a rigorous theoretical examination arise in the case when the system has vibrations with intermediate frequencies. It is the aim of this work to estimate the effect of an intermediate local vibration on the preexponential factor and on the activation energy while assuming that transitions between terms corresponding to different vibrational states of this degree of freedom occur independently, and allowing for the possibility that the transitions between terms are adiabatic in character. The authors report results obtained in numerical computer calculations for different values of the parameters.

  5. Frequency domain measurement systems

    NASA Technical Reports Server (NTRS)

    Eischer, M. C.

    1978-01-01

    Stable frequency sources and signal processing blocks were characterized by their noise spectra, both discrete and random, in the frequency domain. Conventional measures are outlined, and systems for performing the measurements are described. Broad coverage of system configurations which were found useful is given. Their functioning and areas of application are discussed briefly. Particular attention is given to some of the potential error sources in the measurement procedures, system configurations, double-balanced-mixer-phase-detectors, and application of measuring instruments.

  6. 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.

  7. Intermediate photovoltaic system/utility interface experience

    NASA Astrophysics Data System (ADS)

    Biringer, K. L.; McDowell, J. F.; Rogers, C. B.; Haskins, D. E.

    A description is given of 11 intermediate photovoltaic application projects, including the Arizona Public Service Company project, the E-Systems 27 kW photovoltaic concentrator application experiment, a 110 kW photovoltaic application experiment in Orlando, Florida, the Lea County photovoltaic flat plate photovoltaic experiment in southeastern New Mexico, the Mt. Laguna photovoltaic flat plate installation in California, the San Bernardino 35 kW photovoltaic flat plate project in California, and the Solar Power flat plate photovoltaic experiment in Massachusetts. It is pointed out that the most significant point to be made relative to the interface of photovoltaic systems with the utility grid is that it can be done successfully.

  8. Navigating Intermediate Targets: The Nervous System Midline

    PubMed Central

    Dickson, Barry J.; Zou, Yimin

    2010-01-01

    In a bilaterally symmetric animal, the midline plays a key role in directing axon growth during wiring of the nervous system. Midline cells provide a variety of guidance cues for growing axons, to which different types of axons respond in different ways and at different times. For some axons, the midline is an intermediate target. They first seek it out, but then move on towards their final targets on the opposite side. For others, the midline is a repulsive barrier that keeps them on their own side of the midline. And for many of these axons the midline provides signals that guide them along specific lateral pathways or up and down the longitudinal axis. PMID:20534708

  9. 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.

  10. The effect of intermediate frequency on sheath dynamics in collisionless current driven triple frequency capacitive plasmas

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Mishra, S. K.; Kaw, P. K.; Turner, M. M.

    2017-01-01

    The Capacitively Coupled Plasma discharge featuring operation in current driven triple frequency configuration has analytically been investigated, and the outcome is verified by utilising the 1D3V particle-in-cell (PIC) simulation code. In this analysis, the role of middle frequency component of the applied signal has precisely been explored. The discharge parameters are seen to be sensitive to the ratio of the chosen middle frequency to lower and higher frequencies for fixed amplitudes of the three frequency components. On the basis of analysis and PIC simulation results, the middle frequency component is demonstrated to act as additional control over sheath potential, electron sheath heating, and ion energy distribution function (iedf) of the plasma discharge. For the electron sheath heating, effect of the middle frequency is seen to be pronounced as it approaches to the lower frequency component. On the other hand, for the iedf, the control is more sensitive as the middle frequency approaches towards the higher frequency. The PIC estimate for the electron sheath heating is found to be in reasonably good agreement with the analytical prediction based on the Kaganovich formulation.

  11. 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.

  12. 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.

  13. Number Frequency in L1 Differentially Affects Immediate Serial Recall of Numbers in L2 Between Beginning and Intermediate Learners.

    PubMed

    Sumioka, Norihiko; Williams, Atsuko; Yamada, Jun

    2016-12-01

    A list number recall test in English (L2) was administered to both Japanese (L1) students with beginning-level English proficiency who attended evening high school and Japanese college students with intermediate-level English proficiency. The major findings were that, only for the high school group, the small numbers 1 and 2 in middle positions of lists were recalled better than the large numbers 8 and 9 and there was a significant correlation between number frequency in Japanese and recall performance. Equally intriguing was that in both groups for adjacent transposition errors, smaller numbers tended to appear in the first position and large numbers in the second; also, omission errors were commonly seen for larger numbers. These phenomena are interpreted as reflecting frequency and/or frequency-related effects. Briefly discussed were the bilingual short-term memory system, effects of number value, generality and implications of the findings, and weaknesses of the study.

  14. Mechanisms of deterioration of intermediate moisture food systems

    NASA Technical Reports Server (NTRS)

    Labuza, T. P.

    1972-01-01

    A study of shelf stability in intermediate moisture foods was made. Major efforts were made to control lipid oxidation and nonenzymatic browning. In order to determine means of preventing these reactions, model systems were developed having the same water activity content relationship of intermediate moisture foods. Models were based on a cellulose-lipid and protein-lipid system with glycerol added as the humectant. Experiments with both systems indicate that lipid oxidation is promoted significantly in the intermediate moisture range. The effect appeared to be related to increased mobility of either reactants or catalysts, since when the amount of water in the system reached a level where capillary condensation occurred and thus free water was present, the rates of oxidation increased. With added glycerol, which is water soluble and thus increases the amount of mobile phase, the increase in oxidation rate occurs at a lower relative humidity. The rates of oxidation were maximized at 61% RH and decreased again at 75% RH probably due to dilution. No significant non-enzymatic browning occurred in the protein-lipid systems. Prevention of oxidation by the use of metal chelating agents was enhanced in the cellulose system, whereas, with protein present, the lipid soluble chain terminating antioxidants (such as BHA) worked equally as well. Preliminary studies of foods adjusted to the intermediate moisture range bear out the results of oxidation in model systems. It can be concluded that for most fat containing intermediate moisture foods, rancidity will be the reaction most limiting stability.

  15. 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.

  16. 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

  17. PAH Intermediates: Links between the Atmosphere and Biological Systems

    PubMed Central

    SIMONICH, STACI L. MASSEY; MOTORYKIN, OLEKSII; JARIYASOPIT, NARUMOL

    2010-01-01

    China is now the world's largest emitter of polycyclic aromatic hydrocarbons (PAHs). In addition, PAHs, and their reactive intermediates, undergo trans-Pacific atmospheric transport to the Western U.S. The objectives of our research are to predict, identify and quantify novel PAH intermediates in the atmosphere and biological systems, using computational methods, as well as laboratory and field experiments. Gaussian is used to predict the thermodynamic properties of parent structure PAHs, as well as the associated nitro-, oxy-, and hydroxy- PAH intermediates. Based on these predictions, state-of-the-art analytical chemistry techniques are used to identify and quantify these potential intermediates on Asian particulate matter before and after reaction in a continuous flow photochemical reactor. These same techniques are used to identify the relative proportion of PAH intermediates in PAH source regions (such as Beijing, China) and during long-range atmospheric transport to the Western U.S. PAH personal exposure studies in China and the Confederated Tribes of the Umatilla Indian Reservation in Oregon will be used to assess the similarities and differences in the PAH intermediates in biological systems relative to the atmosphere. PMID:20849837

  18. Hydrochemistry of the surficial and intermediate aquifer systems in Florida

    USGS Publications Warehouse

    Berndt, M.P.; Katz, B.G.

    1992-01-01

    Hydrochemistry of the surficial and intermediate aquifer systems in Florida reflects the lithology and mineralogy of units within each aquifer and sources of water to each aquifer. The surficial aquifer system consists of sand, sandstone, clay, limestone, and shell units that are recharged primarily by precipitation. Calcium bicarbonate was the major-ion water type for 53 percent of the surficial aquifer determinations; a mixed water type (no dominant ions) accounted for 37 percent of the determinations. The median dissolved-solids concentration for the surficial aquifer system was 341 milligrams per liter. The intermediate aquifer system consists of limestone, dolomite, sand, and sandstone, and sources of water include downward leakage from the surficial aquifer system and, in some areas, upward leakage from the Upper Floridan aquifer. In northeastern and panhandle areas of Florida, water from the intermediate aquifer system had major-ion and dissolved-solids concentrations similar to water from the surficial aquifer system. In southwestern Florida, the water type in 67 percent of analyses was mixed, and the median dissolved-solids concentration was 642 milligrams per liter. In a northern area of southwestern Florida, hydrochemistry in the limestone aquifer of the intermediate aquifer system is similar to downward leakage from the surficial aquifer system. In a southern area, downward leakage from the surficial aquifer system has calcium and bicarbonate concentrations five times higher than in the northern area, and upward leakage from the Upper Floridan aquifer contains sodium chloride type water from mixing with seawater. In southern southwest Florida, both the limestone aquifer and the overlying sandstone aquifer within the intermediate aquifer system had higher calcium, sodium, chloride, and bicarbonate concentrations than the limestone aquifer in northern southwest Florida.

  19. 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.

  20. 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…

  1. 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…

  2. 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.

  3. Compressing Green's function using intermediate representation between imaginary-time and real-frequency domains

    NASA Astrophysics Data System (ADS)

    Shinaoka, Hiroshi; Otsuki, Junya; Ohzeki, Masayuki; Yoshimi, Kazuyoshi

    2017-07-01

    Model-independent compact representations of imaginary-time data are presented in terms of the intermediate representation (IR) of analytical continuation. We demonstrate the efficiency of the IR through continuous-time quantum Monte Carlo calculations of an Anderson impurity model. We find that the IR yields a significantly compact form of various types of correlation functions. This allows the direct quantum Monte Carlo measurement of Green's functions in a compressed form, which considerably reduces the computational cost and memory usage. Furthermore, the present framework will provide general ways to boost the power of cutting-edge diagrammatic/quantum Monte Carlo treatments of many-body systems.

  4. 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.

  5. Power enhanced frequency conversion system

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  6. Optimal control of systems with intermediate phase constraints

    SciTech Connect

    Kirichenko, S.B.

    1995-03-01

    In this paper, we derive necessary conditions of minimum for the general optimal control problem with the following characteristics: the trajectory is corrected at intermediate time instants using matching relationships; the system dynamics may vary in each time interval; the optimand functional and the functional constraints depend on the intermediate time instants, the momenta, and the phase coordinates of the trajectories. The result is derived by the methods of modern optimization theory and nonsmooth analysis. It is presented in the form of a maximum principle. The specific solution scheme for this problem has been developed in greater detail elsewhere for systems of the form x{sub i}={line_integral}{sub i}(t, x{sub i}). Much of the previous manipulations and results on the structure of the conjugate cone and the form of the directional derivatives are used also in this paper. This is legitimate because the optimized parameters and controls are independent.

  7. 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.

  8. Dorsoventral patterning in the Drosophila central nervous system: the intermediate neuroblasts defective homeobox gene specifies intermediate column identity

    PubMed Central

    Weiss, Joseph B.; Von Ohlen, Tonia; Mellerick, Dervla M.; Dressler, Gregory; Doe, Chris Q.; Scott, Matthew P.

    1998-01-01

    One of the first steps in neurogenesis is the diversification of cells along the dorsoventral axis. In Drosophila the central nervous system develops from three longitudinal columns of cells: ventral cells that express the vnd/nk2 homeobox gene, intermediate cells, and dorsal cells that express the msh homeobox gene. Here we describe a new Drosophila homeobox gene, intermediate neuroblasts defective (ind), which is expressed specifically in the intermediate column cells. ind is essential for intermediate column development: Null mutants have a transformation of intermediate to dorsal column neuroectoderm fate, and only 10% of the intermediate column neuroblasts develop. The establishment of dorsoventral column identity involves negative regulation: Vnd represses ind in the ventral column, whereas ind represses msh in the intermediate column. Vertebrate genes closely related to vnd (Nkx2.1 and Nkx2.2), ind (Gsh1 and Gsh2), and msh (Msx1 and Msx3) are expressed in corresponding ventral, intermediate, and dorsal domains during vertebrate neurogenesis, raising the possibility that dorsoventral patterning within the central nervous system is evolutionarily conserved. PMID:9832510

  9. 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

  10. Signal loss in 1D magic-angle spinning exchange NMR (CODEX): radio-frequency limitations and intermediate motions.

    PubMed

    Hackel, Christiane; Franz, Cornelius; Achilles, Anja; Saalwächter, Kay; Reichert, Detlef

    2009-08-28

    The popular 1D MAS exchange experiment CODEX suffers limitations due to signal loss during the finite recoupling periods, during which the magnetization evolves in the transverse plane. Here, we address the origins and possible improvements of this problem, aimed at (i) an optimization of the signal-to-noise ratio in the experiments, as well as harnessing intermediate-motion induced signal loss for obtaining approximate information on (ii) correlation times and (iii) potential distributions, where the latter are often found in polymeric systems. First, we show that the intensity of the signal is sensitive to the radiofrequency (rf) parameters of the carbon recoupling and proton decoupling, and care must be taken to gain optimal signal intensity. Optimum conditions are found for recoupling pulses being as short as possible for large chemical shift anisotropy (CSA) values, and approaching a ratio of 3 between the nutation frequencies for protonated carbons, calling for an individual adjustment in each case. Second, we demonstrate that the effect of intermediate motions can be studied semi-quantitatively by combining CODEX data with its constant-time modification CONTRA, which allows for a tuning of the signal loss due to intermediate motions. Third, for the case of samples featuring a distribution of correlation times, we propose a procedure to obtain an estimate of the proportion of molecular segments in the sample for which the CODEX data are representative, i.e., which share of segments moves truly in the slow-motion regime. The procedure involves the combination of CODEX data with a cross-polarisation (CP) reference experiment for an estimate of the full sample magnetization; it is demonstrated on the example of semi-crystalline poly(ethylene oxide).

  11. Quantum systems under frequency modulation

    NASA Astrophysics Data System (ADS)

    Silveri, M. P.; Tuorila, J. A.; Thuneberg, E. V.; Paraoanu, G. S.

    2017-05-01

    We review the physical phenomena that arise when quantum mechanical energy levels are modulated in time. The dynamics resulting from changes in the transition frequency is a problem studied since the early days of quantum mechanics. It has been of constant interest both experimentally and theoretically since, with the simple two-state model providing an inexhaustible source of novel concepts. When the transition frequency of a quantum system is modulated, several phenomena can be observed, such as Landau-Zener-Stückelberg-Majorana interference, motional averaging and narrowing, and the formation of dressed states with the appearance of sidebands in the spectrum. Adiabatic changes result in the accumulation of geometric phases, which can be used to create topological states. In recent years, an exquisite experimental control in the time domain was gained through the parameters entering the Hamiltonian, and high-fidelity readout schemes allowed the state of the system to be monitored non-destructively. These developments were made in the field of quantum devices, especially in superconducting qubits, as a well as in atomic physics, in particular in ultracold gases. As a result of these advances, it became possible to demonstrate many of the fundamental effects that arise in a quantum system when its transition frequencies are modulated. The purpose of this review is to present some of these developments, from two-state atoms and harmonic oscillators to multilevel and many-particle systems.

  12. Quantum systems under frequency modulation.

    PubMed

    Silveri, M P; Tuorila, J A; Thuneberg, E V; Paraoanu, G S

    2017-05-01

    We review the physical phenomena that arise when quantum mechanical energy levels are modulated in time. The dynamics resulting from changes in the transition frequency is a problem studied since the early days of quantum mechanics. It has been of constant interest both experimentally and theoretically since, with the simple two-state model providing an inexhaustible source of novel concepts. When the transition frequency of a quantum system is modulated, several phenomena can be observed, such as Landau-Zener-Stückelberg-Majorana interference, motional averaging and narrowing, and the formation of dressed states with the appearance of sidebands in the spectrum. Adiabatic changes result in the accumulation of geometric phases, which can be used to create topological states. In recent years, an exquisite experimental control in the time domain was gained through the parameters entering the Hamiltonian, and high-fidelity readout schemes allowed the state of the system to be monitored non-destructively. These developments were made in the field of quantum devices, especially in superconducting qubits, as a well as in atomic physics, in particular in ultracold gases. As a result of these advances, it became possible to demonstrate many of the fundamental effects that arise in a quantum system when its transition frequencies are modulated. The purpose of this review is to present some of these developments, from two-state atoms and harmonic oscillators to multilevel and many-particle systems.

  13. Optogenetic fMRI reveals distinct, frequency-dependent networks recruited by dorsal and intermediate hippocampus stimulations

    PubMed Central

    Weitz, Andrew J.; Fang, Zhongnan; Lee, Hyun Joo; Fisher, Robert S.; Smith, Wesley C.; Choy, ManKin; Liu, Jia; Lin, Peter; Rosenberg, Matthew; Lee, Jin Hyung

    2014-01-01

    Although the connectivity of hippocampal circuits has been extensively studied, the way in which these connections give rise to large-scale dynamic network activity remains unknown. Here, we used optogenetic fMRI to visualize the brain network dynamics evoked by different frequencies of stimulation of two distinct neuronal populations within dorsal and intermediate hippocampus. Stimulation of excitatory cells in intermediate hippocampus caused widespread cortical and subcortical recruitment at high frequencies, whereas stimulation in dorsal hippocampus led to activity primarily restricted to hippocampus across all frequencies tested. Sustained hippocampal responses evoked during high-frequency stimulation of either location predicted seizure-like afterdischarges in video-EEG experiments, while the widespread activation evoked by high-frequency stimulation of intermediate hippocampus predicted behavioral seizures. A negative BOLD signal observed in dentate gyrus during dorsal, but not intermediate, hippocampus stimulation is proposed to underlie the mechanism for these differences. Collectively, our results provide insight into the dynamic function of hippocampal networks and their role in seizures. PMID:25462689

  14. Monolithically integrated absolute frequency comb laser system

    SciTech Connect

    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. Relations between acoustic cavitation and skin resistance during intermediate- and high-frequency sonophoresis.

    PubMed

    Rich, Kyle T; Hoerig, Cameron L; Rao, Marepalli B; Mast, T Douglas

    2014-11-28

    Enhanced skin permeability is known to be achieved during sonophoresis due to ultrasound-induced cavitation. However, the mechanistic role of cavitation during sonophoresis has been extensively investigated only for low-frequency (LFS, <100 kHz) applications. Here, mechanisms of permeability-enhancing stable and inertial cavitation were investigated by passively monitoring subharmonic and broadband emissions arising from cavitation isolated within or external to porcine skin in vitro during intermediate- (IFS, 100-700 kHz) and high-frequency sonophoresis (HFS, >1 MHz). The electrical resistance of skin, a surrogate measure of the permeability of skin to a variety of compounds, was measured to quantify the reduction and subsequent recovery of the skin barrier during and after exposure to pulsed (1 second pulse, 20% duty cycle) 0.41 and 2.0 MHz ultrasound over a range of acoustic powers (0-21.7 W) for 30 min. During IFS, significant skin resistance reductions and acoustic emissions from cavitation were measured exclusively when cavitation was isolated outside of the skin. Time-dependent skin resistance reductions measured during IFS correlated significantly with subharmonic and broadband emission levels. During HFS, significant skin resistance reductions were accompanied by significant acoustic emissions from cavitation measured during trials that isolated cavitation activity either outside of skin or within skin. Time-dependent skin resistance reductions measured during HFS correlated significantly greater with subharmonic than with broadband emission levels. The reduction of the skin barrier due to sonophoresis was reversible in all trials; however, effects incurred during IFS recovered more slowly and persisted over a longer period of time than HFS. These results quantitatively demonstrate the significance of cavitation during sonophoresis and suggest that the mechanisms and post-treatment longevity of permeability enhancement due to IFS and HFS treatments are

  16. In situ exposure assessment of intermediate frequency fields of diverse devices.

    PubMed

    Van Den Bossche, Matthias; Verloock, Leen; Aerts, Sam; Joseph, Wout; Martens, Luc

    2015-04-01

    In this study, in situ exposure assessment of both electric and magnetic fields of different intermediate frequency (IF) sources is investigated. The authors investigated smart boards and touchscreens, energy-saving bulbs, fluorescent lamps, a portable hearing unit and an electrosurgical unit (ESU). For most of these sources, the electric field is the dominating quantity. International Commission on Non-Ionizing Radiation Protection reference levels are exceeded for touchscreens (44 kHz: up to 155.7 V m(-1) at 5 cm), energy-saving bulbs (38-52 kHz: up to 117.3 V m(-1)), fluorescent lamps (52 kHz: up to 471 V m(-1) at 5 cm) and ESUs (up to 920 kHz: 792 V m(-1) at 0.5 cm). Magnetic field strengths up to 1.8 and 10.5 A m(-1) were measured close to the ESU and portable hearing unit (69 V m(-1)), respectively. Large differences of measured field values exist among the various operating modes of the IF equipment. Compliance distances for general public range from 15.3 cm (touchscreen) to 25 cm (fluorescent lamps). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. 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.

  18. 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.

  19. 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).

  20. 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.

  1. Constancy of intermediate-degree p-mode frequencies during the declining phase of solar cycle 21

    SciTech Connect

    Rhodes, E.J. Jr.; Woodard, M.F.; Cacciani, A.; Tomczyk, S.; Korzennik, S.G.

    1988-03-01

    A comparison was made between two sets of frequencies of intermediate-degree solar p-mode oscillations obtained in late 1981 and mid-1984. Good agreement was found at the 0.02 microHz level despite the 2.6 yr interval separating the two sets of observations. In particular, a comparison was made between the frequencies of 573 modes obtained at the South Pole during December 24-25, 1981 and those of the same modes as observed at the Mount Wilson Observatory 60-ft Solar Tower during July 29-August 13, 1984. The present results are consistent with no change in intermediate-degree p-mode frequencies between late 1981 and mid-1985. 17 references.

  2. On the constancy of intermediate-degree p-mode frequencies during the declining phase of solar cycle 21

    NASA Technical Reports Server (NTRS)

    Rhodes, Edward J., Jr.; Woodard, Martin F.; Cacciani, Alessandro; Tomczyk, Steven; Korzennik, Sylvain G.

    1988-01-01

    A comparison was made between two sets of frequencies of intermediate-degree solar p-mode oscillations obtained in late 1981 and mid-1984. Good agreement was found at the 0.02 microHz level despite the 2.6 yr interval separating the two sets of observations. In particular, a comparison was made between the frequencies of 573 modes obtained at the South Pole during December 24-25, 1981 and those of the same modes as observed at the Mount Wilson Observatory 60-ft Solar Tower during July 29-August 13, 1984. The present results are consistent with no change in intermediate-degree p-mode frequencies between late 1981 and mid-1985.

  3. 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.

  4. 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.

  5. Characterizing global evolutions of complex systems via intermediate network representations.

    PubMed

    Iwayama, Koji; Hirata, Yoshito; Takahashi, Kohske; Watanabe, Katsumi; Aihara, Kazuyuki; Suzuki, Hideyuki

    2012-01-01

    Recent developments in measurement techniques have enabled us to observe the time series of many components simultaneously. Thus, it is important to understand not only the dynamics of individual time series but also their interactions. Although there are many methods for analysing the interaction between two or more time series, there are very few methods that describe global changes of the interactions over time. Here, we propose an approach to visualise time evolution for the global changes of the interactions in complex systems. This approach consists of two steps. In the first step, we construct a meta-time series of networks. In the second step, we analyse and visualise this meta-time series by using distance and recurrence plots. Our two-step approach involving intermediate network representations elucidates the half-a-day periodicity of foreign exchange markets and a singular functional network in the brain related to perceptual alternations.

  6. Characterizing global evolutions of complex systems via intermediate network representations

    NASA Astrophysics Data System (ADS)

    Iwayama, Koji; Hirata, Yoshito; Takahashi, Kohske; Watanabe, Katsumi; Aihara, Kazuyuki; Suzuki, Hideyuki

    2012-05-01

    Recent developments in measurement techniques have enabled us to observe the time series of many components simultaneously. Thus, it is important to understand not only the dynamics of individual time series but also their interactions. Although there are many methods for analysing the interaction between two or more time series, there are very few methods that describe global changes of the interactions over time. Here, we propose an approach to visualise time evolution for the global changes of the interactions in complex systems. This approach consists of two steps. In the first step, we construct a meta-time series of networks. In the second step, we analyse and visualise this meta-time series by using distance and recurrence plots. Our two-step approach involving intermediate network representations elucidates the half-a-day periodicity of foreign exchange markets and a singular functional network in the brain related to perceptual alternations.

  7. Plasticity of intermediate mechanics students' coordinate system choice

    NASA Astrophysics Data System (ADS)

    Sayre, Eleanor C.; Wittmann, Michael C.

    2008-12-01

    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 prior physics and mathematics classes. In small-group interviews and in homework help sessions, we ask students to define a coordinate system and set up the equations of motion for a simple pendulum for which polar coordinates are more appropriate. We analyze video data from several encounters using a combination of Process/Object theory and Resource Theory. We find that students sometimes persist in using an inappropriate Cartesian system. Furthermore, students often derive (rather than recall) the details of the polar coordinate system, indicating that their knowledge is far from solid. To describe our work more precisely, we define a scale of plasticity and several heuristics for defining resources and their plasticity.

  8. A novel, multichannel, comb-frequency Doppler backscatter system

    SciTech Connect

    Peebles, W. A.; Rhodes, T. L.; Hillesheim, J. C.; Zeng, L.; Wannberg, C.

    2010-10-15

    Doppler backscattering has emerged in recent years as a powerful diagnostic tool in high temperature fusion plasmas. The technique is sensitive to plasma turbulence flow and has been utilized to determine radial electric field and to study geodesic acoustic modes, zonal flows, and intermediate scale density turbulence. The current manuscript describes a novel technique for creating a stable, multichannel system covering the V-band frequency range (50-75 GHz) which enables simultaneous monitoring of turbulent flows and fluctuation levels at eight distinct spatial locations. The system is based on a high-frequency, low phase noise comb-frequency generator combined with a filter bank and quadrature detection system. The system is now in operation on DIII-D and has allowed monitoring of the flow and turbulence levels across the plasma radius during events such as the L-H transition.

  9. 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.

  10. 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.

  11. 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.

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

    USDA-ARS?s Scientific Manuscript database

    “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...

  13. NMDA receptor-dependent synaptic plasticity in dorsal and intermediate hippocampus exhibits distinct frequency-dependent profiles.

    PubMed

    Kenney, Jana; Manahan-Vaughan, Denise

    2013-11-01

    The hippocampus may be functionally differentiated along its dorsoventral axis. In contrast to the wealth of data available on synaptic plasticity mechanisms in the dorsal hippocampus, little is known about synaptic plasticity processes in the intermediate hippocampus. Behavioral data suggest that this structure may play a distinct role in learning and memory. Here, we compared amplitudes, frequency-dependency and persistency of long-term potentiation (LTP) and long-term depression (LTD) in the dorsal (DDG) and intermediate dentate gyrus (IDG). In freely moving rats, high-frequency stimulation (HFS) at 200 Hz (10 burst of 15 stimuli) elicited LTP of similar magnitude in both structures that persisted for over 24 h. The intermediate dentate gyrus is more likely to exhibit persistent LTP than its dorsal counterpart, however: HFS at 200 Hz (3 or 1 burst(s)) or 100 Hz elicited short-term potentiation (STP) in DDG, unlike in the IDG, where LTP could be recorded for at least 4 h. Whereas low frequency stimulation (LFS) at 1 Hz elicited long-lasting LTD (>24 h) in the DDG, it had no significant effect on fEPSP profile in the IDG. LFS at 2 Hz elicited short-term depression in DDG and had no effect in IDG. LTP in both IDG and DDG required activation of N-methyl-D-aspartate receptors. Paired-pulse and input-output responses differed in IDG and DDG. Our data suggest that afferent input from the entorhinal cortex generates a different response profile in the dorsal vs. intermediate DG, which may in turn relate to their postulated distinct roles in synaptic information processing and memory formation. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Observations of low and intermediate-frequency-peaked BL Lacs above 100 GeV with VERITAS

    NASA Astrophysics Data System (ADS)

    Errando, M.

    2013-12-01

    Most of the ~ 50 blazars detected to date at TeV energies (E > 0.1 TeV) are high-frequency-peaked BL Lacs (HBLs). Only a handful episodic detections of low- and intermediate-frequency-peaked BL Lacs (LBL/IBLs, with synchrotron peak frequencies in the infrared and optical regime) have been reported by ground-based gamma-ray telescopes, typically during high-flux states. The VERITAS array located in southern Arizona has observed five known TeV LBL/IBLs since 2009: 3C 66A, WComae, PKS 1424+240, S5 0716+714 and BL Lacertae, with exposures of 5-10 hours/year, which so far resulted in the detection of a bright, sub-hour timescale gamma-ray flare of BL Lacertae in June 2011. We also report the detection and characterization of two new IBLs: VER J0521+211 and B2 1215+30.

  15. 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}.

  16. 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.

  17. Flexible alternatives to constant frequency systems

    NASA Astrophysics Data System (ADS)

    Stewart-Wilson, John

    The use of hybrid systems in which variable frequency is used as generated, with a proportion being converted to constant frequency by electronic conversion, is examined as a flexible alternative to constant frequency systems. Here, some practical solutions to the technical issues raised by adopting the more flexible approach to electrical system generation are presented. In particular, attention is given to the frequency ranges used, impact on aircraft equipment, motor-driven equipment, transformer rectifier units, lighting, and avionics. The discussion also covers fan-assisted galley ovens, system architecture, special airworthiness requirements, and power quality.

  18. Discoveries of high-frequency QPOs from intermediate-mass black holes with XMM, RXTE and NICER

    NASA Astrophysics Data System (ADS)

    Ranga Reddy Pasham, Deeraj; Strohmayer, Tod E.; Steiner, James F.

    2017-08-01

    Stable, twin-peak X-ray quasi-periodic oscillations (QPOs; frequency range of 100-450 Hz) in a 3:2 frequency ratio have been observed from a sample of stellar-mass black holes (e.g., Belloni et al. 2012). These frequencies scale inversely with the black hole mass as expected from general relativistic motion near a black hole. Under the black hole unification paradigm, it has been argued that intermediate-mass black holes (IMBH) should also exhibit the 3:2 ratio high-frequency QPOs, but at frequencies lower than stellar-mass black holes. Thence, such QPOs will provide an accurate measurement of IMBH masses (Abramowicz et al. 2004).Combining all the entire archival RXTE/PCA observations of the ultraluminous X-ray source (ULX) M82 X-1, we discovered stable, twin-peak X-ray QPOs at 3.3 and 5 Hz (3:2 frequency ratio). Scaling these frequencies to the oscillations of the stellar-mass black holes of known mass implies that M82 X-1's black hole is 428+-105 solar masses (Pasham, Strohmayer & Mushotzky 2014). We discovered similar 3:2 frequency ratio QPOs from another ULX NGC 1313 X-1 (0.30 and 0.45 Hz). These frequencies imply a black hole mass of 5000+-1300 solar masses in NGC 1313 X-1 (Pasham et al. 2015b). In addition to these results I will discuss some early results from NICER observations of ULXs.

  19. 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.

  20. High frequency power distribution system

    NASA Astrophysics Data System (ADS)

    Patel, Mikund R.

    1986-04-01

    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.

  1. Inverse synthetic aperture radar imaging compensation method based on coherent processing of intermediate frequency direct sampling data

    NASA Astrophysics Data System (ADS)

    Zou, Jiangwei; Tian, Biao; Chen, Zengping

    2016-07-01

    An inverse synthetic aperture radar (ISAR) high-precision compensation method is proposed based on coherent processing of intermediate frequency direct sampling data. First, the compensation of high-speed movement is performed by a modified linear frequency modulation matched filter during the pulse compression. The motion trajectory in the down-range direction is then reconstructed by compensation of window sampling difference of each pulse. Modified envelope correlation is applied to calculate the range profile shift between each pulse and the first one. Polynomial fitting is adopted to accurately estimate the motion characteristics. Subsequently, coherent processing is applied by combining range alignment and initial phase compensation. The migration through range cells correction can be then realized by keystone transform to the highly coherent data. Consequently, ISAR images with high quality are achieved. Experimental results on simulated and real data have demonstrated the validity of the proposed method.

  2. An introduction to high frequency radioteletype systems

    NASA Astrophysics Data System (ADS)

    Pinnau, Roger R.

    1989-10-01

    A basic introductory guide is provided to modern High Frequency (HF) data communications systems. Described are modern commercial radioteletype systems, data communication protocols, and various secrets of the trade.

  3. 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

  4. [Multi-center study on the treatment for intermediate and high-frequency sudden sensorineural hearing loss].

    PubMed

    Wang, Ming-ming; Fan, Zhao-min; Luo, Jian-fen; Hou, Zhi-qiang; Ai, Yu; Wang, Hai-bo; Xu, Min; Zhu, Kang; Hou, Jin; Li, Wen-yan

    2013-05-01

    To analyze the therapeutic effect of treatment for intermediate and high-frequency sudden sensorineural hearing loss (SSNHL). A prospective clinical multicentre research was conducted using international standardized approach of clinical research. SSNHL Cases with intermediate and high-frequency hearing loss, that accepted no medication from onset of hearing loss within two weeks duration and ages ranged between 18 and 65, were collected. All patients were treated by one of four treatments plans chosen by unified random table. 141 patients with intermediate and high-frequency SSNHL were recruited in the research. Twenty subjects were treated with lidocaine, 21 cases with lidocaine and hormone, 40 cases with Ginaton, and 60 cases with Ginaton and hormone. 42 out of 141 (29.79%) patients were total recovery, 24 (17.02%)achieved excellent recovery, 27 (19.15%)achieved partial recovery, and 48 (34.04%) were ineffective. The total effective rate was 65.96%. In lidocaine group, the total effective rate was 55.00%, 66.67% in lidocaine and hormone group, 67.50% in Ginaton group, and 68.33% in Ginaton and hormone group. Considering the total effective rate, there was no statistical difference between four groups (P > 0.05). However, the recovery rate in Ginaton group was significant difference comparing with that in lidocaine group (P = 0.0496). 119 had concomitant symptom of tinnitus, and the tinnitus was improved in patients of 81.51%. With regard to total effective rate of tinnitus in four treatment groups, it was 57.89% (11/19) in lidocaine group, 100.00% (18/18) in lidocaine and hormone group, 88.57% (31/35) in Ginaton group, 78.72% (37/47) in Ginaton and hormone group. There was significant ascendancy in lidocaine and hormone group versus that in lidocaine group (P = 0.002) and Ginaton and hormone group (P = 0.029). And the difference between lidocaine and Ginaton groups was statistical significance (χ(2) = 6.705, P < 0.05). In 43 patients with muffled symptom in

  5. Nanoelectromechanical systems: Nanodevice motion at microwave frequencies

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

  6. Quantifying intermediate-frequency heterogeneities of SOFC electrodes using X-ray computed tomography

    DOE PAGES

    Epting, William K.; Mansley, Zachary; Menasche, David B.; ...

    2017-03-03

    The electrodes in solid oxide fuel cells (SOFCs) consist of three phases interconnected in three dimensions. The volume needed to describe quantitatively such microstructures depends on several lengths scales, which are functions of materials properties and fabrication methods. This work focuses on quantifying the volume needed to represent “intermediate frequency” heterogeneities in electrodes of a commercial SOFC using X-ray computed tomography (CT) over two different length scales. Electrode volumes of 150 x 150 x 9 μm3 were extracted from a synchrotron-based micro-CT data set, with 13 μm3 voxels. 13.6 x 19.8 x 19.4 μm3 of the cathode and 26.3 xmore » 24.8 x 15.7 μm3 of the anode were extracted from laboratory nano-CT data sets, both with 653 nm3 voxels. After comparing the variation across sub-regions for the greyscale values from the micro-CT, and for the phase fractions and triple phase boundary densities from the nano-CT, it was found that the sub-region length scales needed to yield statistically similar average values were an order of magnitude larger than those expected to capture the “high frequency” heterogeneity related to the discrete nature of the three phases in electrodes. In conclusion, the challenge of quantifying such electrodes using available experimental methods is discussed.« less

  7. Hydrogeology of the surficial and intermediate aquifer systems in Sarasota and adjacent counties, Florida

    USGS Publications Warehouse

    Barr, G.L.

    1996-01-01

    From 1991 to 1995, the hydrogeology of the surficial aquifer system and the major permeable zones and confining units of the intermediate aquifer system in southwest Florida was studied. The study area is a 1,400-square-mile area that includes Sarasota County and parts of Manatee, De Soto, Charlotte, and Lee Counties. Lithologic, geophysical, hydraulic property, and water-level data were used to correlate the hydrogeology and map the extent of the aquifer systems. Water chemistry was evaluated in southwest Sarasota County to determine salinity of the surficial and intermediate aquifer systems. The surficial aquifer is an unconfined aquifer system that overlies the intermediate aquifer system and ranges from a few feet to over 60 feet in thickness in the study area. Hydraulic properties of the surficial aquifer system determined from aquifer and laboratory tests, and model simulations vary considerably across the study area. The intermediate aquifer system, a confined aquifer system that lies between the surficial and the Upper Floridan aquifers, is composed of alternating confining units and permeable zones. The intermediate aquifer system has three major permeable zones that exhibit a wide range of hydraulic properties. Horizontal flow in the intermediate aquifer system is northeast to southwest. Most of the study area is in a discharge area of the intermediate aquifer system. Water ranges naturally from fresh in the surficial aquifer system and upper permeable zones of the intermediate aquifer system to moderately saline in the lower permeable zone. Water-quality data collected in coastal southwest Sarasota County indicate that ground-water withdrawals from major pumping centers have resulted in lateral seawater intrusion and upconing into the surficial and intermediate aquifer systems.

  8. Exact free vibration analysis for mechanical system composed of Timoshenko beams with intermediate eccentric rigid body on elastic supports: An experimental and analytical investigation

    NASA Astrophysics Data System (ADS)

    Farghaly, S. H.; El-Sayed, T. A.

    2017-01-01

    The purpose of this article is to investigate the changes in the magnitude of natural frequencies and their associated modal shapes of Timoshenko beam with respect to different system design parameters. This beam includes an intermediate extended eccentric rigid mass mounted on two elastic segments. The equilibrium equations which govern the transverse and rotational motions are derived. The application of the developed system frequency equation is demonstrated by several illustrative examples. Several end and intermediate conditions are considered. The influence of, rotary inertia, shear deformation, axial load, eccentric mass and elastic segments step ratio on the system natural frequencies and mode shapes are conducted. Several sets of new results are presented. Comparison of the present model results with the experimental data for shaft integrated with intermediate rigid mass demonstrates the accuracy of the analysis in practical applications. The present model is valid for several industrial applications, such as mechanical, structural, naval and for wider range of applications.

  9. Electromagnetic fluctuations in the intermediate frequency range originating from a plasma boundary layer

    NASA Astrophysics Data System (ADS)

    Enloe, C. L.; Tejero, E. M.; Crabtree, C.; Ganguli, G.; Amatucci, W. E.

    2017-05-01

    We demonstrate the transition in the waves generated by the electron-ion hybrid instability from a predominantly electrostatic to a predominantly electromagnetic character in a magnetized cylindrical laboratory plasma, in which we have induced sheared electron flow, transverse to the axial magnetic field and localized to a narrow azimuthal region. The transition occurs when the density of the plasma is increased, so that the electron skin depth is reduced to the same order as the wavelength of the waves. In the electromagnetic mode, we observe prominent bursts in the wave activity exhibiting substantial (up to 30%) frequency chirp, randomly occurring at a rate that is highly sensitive to the electric field structure in the boundary layer.

  10. 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.

  11. A low frequency RFI monitoring system

    NASA Astrophysics Data System (ADS)

    Amiri, Shahram; Shankar, N. Udaya; Girish, B. S.; Somashekar, R.

    Radio frequency interference (RFI) is a growing problem for research in radio astronomy particularly at wavelengths longer than 2m. For satisfactory operation of a radio telescope, several bands have been protected for radio astronomy observations by the International Telecommunication Union. Since the radiation from cosmic sources are typically 40 to 100 dB below the emission from services operating in unprotected bands, often the out-of-band emission limits the sensitivity of astronomical observations. Moreover, several radio spectral emissions from cosmic sources are present in the frequency range outside the allocated band for radio astronomy. Thus monitoring of RFI is essential before building a receiver system for low frequency radio astronomy. We describe the design and development of an RFI monitoring system operating in the frequency band 30 to 100 MHz. This was designed keeping in view our proposal to extend the frequency of operation of GMRT down to 40 MHz. The monitor is a PC based spectrometer recording the voltage output of a receiver connected to an antenna, capable of digitizing the low frequency RF directly with an 8 bit ADC and sampling bandwidths up to 16 MHz. The system can operate continuously in almost real-time with a loss of only 2% of data. Here we will present the systems design aspects and the results of RFI monitoring carried out at the Raman Research Institute, Bangalore and at the GMRT site in Khodad.

  12. 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.

  13. 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.

  14. Environmental radiological survey of the intermediate-level waste system pipeline

    SciTech Connect

    Ohnesorge, W.F.; Oakes, T.W.; Parsons, D.W.; Malone, J.L.

    1981-09-01

    This publication gives the results of a February 1979 radiation survey of the intermediate-level waste system pipeline. Survey techniques and recommendations for health physics monitoring during cleanup are included.

  15. Modelling the spectral induced polarization response of water-saturated sands in the intermediate frequency range (102-105 Hz) using mechanistic and empirical approaches

    NASA Astrophysics Data System (ADS)

    Kremer, Thomas; Schmutz, Myriam; Leroy, Philippe; Agrinier, Pierre; Maineult, Alexis

    2016-11-01

    The intermediate frequency range 102-105 Hz forms the transition range between the spectral induced polarization frequency domain and the dielectric spectroscopy frequency domain. Available experimental data showed that the spectral induced polarization response of sands fully saturated with water was particularly sensitive to variations of the saturating water electrical conductivity value in the intermediate frequency range. An empirical and a mechanistic model have been developed and confronted to this experimental data. This confrontation showed that the Maxwell Wagner polarization alone is not sufficient to explain the observed signal in the intermediate frequency range. The SIP response of the media was modelled by assigning relatively high dielectric permittivity values to the sand particle or high effective permittivity values to the media. Such high values are commonly observed in the dielectric spectroscopy literature when entering the intermediate frequency range. The physical origin of these high dielectric permittivity values is discussed (grain shape, electromagnetic coupling), and a preliminary study is presented which suggests that the high impedance values of the non-polarizable electrodes might play a significant role in the observed behaviour.

  16. 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…

  17. 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.

  18. 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.

  19. 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.

  20. Intermediate frequency magnetic field generated by a wireless power transmission device does not cause genotoxicity in vitro.

    PubMed

    Shi, Dejing; Zhu, Chunbo; Lu, Rengui; Mao, Shitong; Qi, Yanhua

    2014-10-01

    The aim of this study was to evaluate effects of intermediate frequency magnetic fields (IFMF) generated by a wireless power transmission (WPT) based on magnetic resonance from the perspective of cellular genotoxicity on cultured human lens epithelial cells (HLECs). We evaluated the effects of exposure to 90 kHz magnetic fields at 93.36 µT on cellular genotoxicity in vitro for 2 and 4 h. The magnetic flux density is approximately 3.5 times higher than the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. For assessment of genotoxicity, we studied cellular proliferation, apoptosis and DNA damage by Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, alkaline comet assay and phosphorylated histone H2AX (γH2AX) foci formation test. We did not detect any effect of a 90 kHz IFMF generated by WPT based on magnetic resonance on cell proliferation, apoptosis, comet assay, and γH2AX foci formation test. Our results indicated that exposure to 90 kHz IFMF generated by WPT based on magnetic resonance at 93.36 µT for 2 and 4 h does not cause detectable cellular genotoxicity.

  1. Potentiometric surface of the intermediate aquifer system, west- central Florida, May 1987

    USGS Publications Warehouse

    Lewelling, B.R.

    1988-01-01

    The intermediate aquifer system within the Southwest Florida Water Management District underlies a 5,000 sq mi area of De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties. The intermediate aquifer system occurs between the overlying surficial aquifer system and the underlying Floridan aquifer system, and consists of layers of sand, shell, clay, marl, limestone, and dolom of the Tamiami, Hawthorn, and Tampa Formations of late Tertiary age. The intermediate aquifer system contains one or more water-bearing units separated by discontinuous confining units. This aquifer system is the principal source of potable water in the southwestern part of the study area and is widely used as a source of water in other parts where wells are open to the intermediate aquifer system or to both the intermediate and Floridan aquifer systems. Yields of individual wells open to the intermediate aquifer system range from a few gallons to several hundred gallons per minute. The volume of water withdrawn from the intermediate aquifer system is considerably less than that withdrawn from the Floridan aquifer system in the study area. The surface was mapped by determining the altitude of water levels in a network of wells and is represented on maps by contours that connect points of equal altitude. The compos potentiometric surface of all water-bearing units within the intermediate aquifer system is shown. In areas where multiple aquifers exist, wells open to all aquifers were selected for water level measurements whenever possible. In the southwestern and lower coastal region of the study area, two aquifers and confining units are described for the intermediate aquifer system: the Tamiami-upper Hawthorn aquifer and the underlying lower Hawthorn-upper Tampa aquifer. The potentiometric surface of the Tamiami-upper Hawthorn aquifer is also shown. Water levels are from wells drilled and open exclusively to that aquifer. The exact boundary for the

  2. High-frequency ultrasonic wire bonding systems

    PubMed

    Tsujino; Yoshihara; Sano; Ihara

    2000-03-01

    The vibration characteristics of longitudinal-complex transverse vibration systems with multiple resonance frequencies of 350-980 kHz for ultrasonic wire bonding of IC, LSI or electronic devices were studied. The complex vibration systems can be applied for direct welding of semiconductor tips (face-down bonding, flip-chip bonding) and packaging of electronic devices. A longitudinal-complex transverse vibration bonding system consists of a complex transverse vibration rod, two driving longitudinal transducers 7.0 mm in diameter and a transverse vibration welding tip. The vibration distributions along ceramic and stainless-steel welding tips were measured at up to 980 kHz. A high-frequency vibration system with a height of 20.7 mm and a weight of less than 15 g was obtained.

  3. 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.

  4. 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

  5. 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.

  6. Odd-frequency superconductivity in driven systems

    NASA Astrophysics Data System (ADS)

    Triola, Christopher; Balatsky, Alexander V.

    2016-09-01

    We show that Berezinskii's classification of the symmetries of Cooper pair amplitudes holds for driven systems even in the absence of translation invariance. We then consider a model Hamiltonian for a superconductor coupled to an external driving potential and, treating the drive as a perturbation, we investigate the corrections to the anomalous Green's function, density of states, and spectral function. We find that in the presence of an external drive the anomalous Green's function develops terms that are odd in frequency and that the same mechanism responsible for these odd-frequency terms generates additional features in the density of states and spectral function.

  7. 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)

  8. Data acquisition system for intermediate energy nuclear experiments

    SciTech Connect

    D'Isep, F.; Maggiora, A.; Minetti, B.; Maron, G.; Morando, M.; Balestra, F.; Masoni, A.

    1989-02-01

    The data acquisition system for the OBELIX experiment at the LEAR antiproton beam is presented. The experimental setup is composed by 5 detectors with different read-out systems. The data acquisition is designed to allow the 5 detectors running all together as well as in stand alone mode., the introduction of some steps of data reduction, global hardware control and statistically significant event control. These goals are reached through a tree of VME crates controlled by a medium range computer and four workstations; the main flux of data flows on a combination of VME and VSB busses, while the system is completely controlled via the Ethernet bus. This design allows a high modularity either in the hardware or in the software.

  9. 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.

  10. Stabilized fiber-optic frequency distribution system

    NASA Technical Reports Server (NTRS)

    Primas, L. E.; Lutes, G. F.; Sydnor, R. L.

    1989-01-01

    A technique for stabilizing reference frequencies transmitted over fiber-optic cable in a frequency distribution system is discussed. The distribution system utilizes fiber-optic cable as the transmission medium to distribute precise reference signals from a frequency standard to remote users. The stability goal of the distribution system is to transmit a 100-MHz signal over a 22-km fiber-optic cable and maintain a stability of 1 part in 10(17) for 1000-second averaging times. Active stabilization of the link is required to reduce phase variations produced by environmental effects, and is achieved by transmitting the reference signal from the frequency standard to the remote unit and then reflecting back to the reference unit over the same optical fiber. By comparing the phase of the transmitted and reflected signals at the reference unit, phase variations of the remote signal can be measured. An error voltage derived from the phase difference between the two signals is used to add correction phase.

  11. 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.

  12. Operational experience with intermediate flat-plate photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Risser, V. V.; Zwibel, H. S.

    Operating features, data acquisition, and fault isolation and maintenance procedures at 20 kWp and 100 kWp photovoltaic (PV) installations in Texas and New Mexico are discussed. Weather and system performance are sensed each minute, averages are calculated for each ten readings, and data is stored on magnetic tape. A total of 84 parameters, including 64 string currents, are recorded at the 20 kWp array and 84 parameters, with 42 string currents, are traced in New Mexico. The 20 kW array is coupled to a 197 MW utility power plant, which determines the voltage of the array. It produced 12 MWh in one yr of operation, functioning at 24 pct overall efficiency. The 100 kWp system is coupled to a 60 kW power conditioning unit and feeds a shopping center, producing 8 pct of the annual load with a cap factor of 25 pct and 192 MWh of dc current produced in one year. It was found that under normal conditions washing the panels is not economically justified in terms of the small power lost if washing does not occur. It is concluded that the PV arrays can be successfully used in an automated operation mode.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Extreme Low Frequency Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

    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.

  18. 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.

  19. Control system for intermediate differential in four-wheel drive vehicle

    SciTech Connect

    Takahashi, T.; Kuramochi, K.; Sayou, S.

    1987-09-01

    A control system is described for an intermediate differential in drive connection to a power transmission in a four-wheel drive vehicle for transmitting a drive power from a prime mover of the vehicle to front and rear wheel drive axles. The intermediate differential is provided with a lock mechanism which is operated under control of an actuator to selectively maintain the intermediate differential in a locked condition or an unlocked condition. The control system consists of: first detecting means arranged to detect a steering angle of the dirigible road wheel for producing a first detection signal therefrom when the steering angle of the road wheel exceeds a predetermined value; second detecting means arranged to detect disconnection of the drive power transmitted to the intermediate differential from the prime mover for producing a second detection signal therefrom when transmission of the drive power is disconnected; and means responsive to the first and second detection signals from the detecting means for controlling the actuator in such a manner that the lock mechanism is operated to release the locked condition of the intermediate differential when the steering angle of the road wheel exceeds the predetermined value in a condition where the transmission of the drive power is disconnected.

  20. 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.

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

    DOE PAGES

    Brown, Nicholas R.; Powers, Jeffrey J.; Feng, B.; ...

    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

  2. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies for automated systems. 80.385... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated systems. This section describes the carrier frequencies for the Automated Maritime Telecommunications...

  3. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for automated systems. 80.385... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Automated Systems § 80.385 Frequencies for automated systems. This section describes the carrier frequencies for the Automated Maritime Telecommunications...

  4. A low frequency rotational energy harvesting system

    NASA Astrophysics Data System (ADS)

    Febbo, M.; Machado, S. P.; Ramirez, J. M.; Gatti, C. D.

    2016-11-01

    This paper presents a rotary power scavenging unit comprised of two systems of flexible beams connected by two masses which are joined by means of a spring, considering a PZT (QP16N, Midé Corporation) piezoelectric sheet mounted on one of the beams. The energy harvesting (EH) system is mounted rigidly on a rotating hub. The gravitational force on the masses causes sustained oscillatory motion in the flexible beams as long as there is rotary motion. The intention is to use the EH system in the wireless autonomous monitoring of wind turbines under different wind conditions. Specifically, the development is oriented to monitor the dynamic state of the blades of a wind generator of 30 KW which rotates between 50 and 150 rpm. The paper shows a complete set of experimental results on three devices, modifying the amount of beams in the frame supporting the system. The results show an acceptable sustained voltage generation for the expected range, in the three proposed cases. Therefore, it is possible to use this system for generating energy in a low-frequency rotating environment. As an alternative, the system can be easily adapted to include an array of piezoelectric sheets to each of the beams, to provide more power generation.

  5. 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.

  6. The design of Gaussian beam zoom system in intermediate and long distance measurement

    NASA Astrophysics Data System (ADS)

    Wang, Mengcheng; Zhou, Jian

    2016-10-01

    It is well known that laser possesses high brightness, high coherence, good directivity and other unique properties. In many practical applications, it is necessary to get small light spot in intermediate and long distance. Intermediate and long distance laser measurement demands to minimize the spot radius in order to improve the spatial resolution of the system and signal quality. Therefore, the study of Gaussian beam focusing property has high value for practical applications. In order to achieve intermediate and long distance laser measurement, this paper studies the method to adjust Gaussian beam spot diameter within a certain range after a near-field optical system transformation to improve the signal quality. Based on the fundamental characteristics of the Gaussian beam, this paper deduces the theoretical formula for the position and radius of the Gaussian beam waist and measures them by means of the CCD method. Then Matlab is used to simulate the spot diameter in the far field, and by combining numerical simulation results as well as optimizing the structure of the actual optical system, we make the light spot diameter in the target area fit the requirements of the laser velocimeter in intermediate and long distance measurement.

  7. 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

  8. Potentiometric surfaces of the intermediate aquifer system, west-central Florida, May, 1993

    USGS Publications Warehouse

    Mularoni, R.A.

    1994-01-01

    The intermediate aquifer system underlies a 5000-sq-mi area including De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties, Florida. It is overlain by the surf@cial aquifer system and underlain by the Floridan aquifer system. The potentiometric surface of the intermediate aquifer system was mapped by determining the altitude of water levels in a network of wells and represented on a map by contours that connect points of equal altitude. This map represents water-level conditions near the end of the spring dry season when ground- water withdrawals for agricultural use were high. The cumulative rainfall for the study area was 4.84 inches above normal for the period from June 1992 to May 1993. Hydrographs for selected wells indicated that the annual and seasonal fluctuations of the water levels were generally large (greater than 15 feet) in the central interior region where water demand for irrigation is high during the fall and spring. Seasonal fluctuations were smaller in the northern recharge area where water use is predominantly for public supply. Water levels measured in May 1993 for the composite intermediate aquifer potentiometric surface were lower than those measured in May or September 1992. A cone of depression exists in the potentiometric surface for the composite aquifer system at Warm Mineral Springs, which is a natural discharge point from this system.

  9. 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.

  10. Number Frequency in L1 Differentially Affects Immediate Serial Recall of Numbers in L2 between Beginning and Intermediate Learners

    ERIC Educational Resources Information Center

    Sumioka, Norihiko; Williams, Atsuko; Yamada, Jun

    2016-01-01

    A list number recall test in English (L2) was administered to both Japanese (L1) students with beginning-level English proficiency who attended evening high school and Japanese college students with intermediate-level English proficiency. The major findings were that, only for the high school group, the small numbers 1 and 2 in middle positions of…

  11. Number Frequency in L1 Differentially Affects Immediate Serial Recall of Numbers in L2 between Beginning and Intermediate Learners

    ERIC Educational Resources Information Center

    Sumioka, Norihiko; Williams, Atsuko; Yamada, Jun

    2016-01-01

    A list number recall test in English (L2) was administered to both Japanese (L1) students with beginning-level English proficiency who attended evening high school and Japanese college students with intermediate-level English proficiency. The major findings were that, only for the high school group, the small numbers 1 and 2 in middle positions of…

  12. Unique frequency-shift-keyed demodulation system

    NASA Technical Reports Server (NTRS)

    Staloff, C.; Teltelbaum, S.

    1968-01-01

    Frequency-Shift-Keyed /FSK/ demodulator provides a frequency discriminator whose outputs are separate and applied to two identical decoding channels, one decoding binary ones and the other decoding binary zeros. This demodulator rejects data applied to it at any frequency higher than design.

  13. 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.

  14. 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.

  15. Effects of polyols on the stability of whey proteins in intermediate-moisture food model systems.

    PubMed

    Liu, Xiaoming; Zhou, Peng; Tran, Amy; Labuza, Ted P

    2009-03-25

    The objective of this study was to investigate the influence of polyols on the stability of whey proteins in an intermediate-moisture food model system and to elucidate the effect of polyols on the hardening of whey protein-based bars during storage. Four major polyols, glycerol, propylene glycol, maltitol, and sorbitol, were evaluated in model systems, which contained whey protein isolate, polyols, and water. The results showed that glycerol was the most effective polyol in lowering water activity and provided the soft texture of intermediate-moisture foods, followed by sorbitol and maltitol. These three polyols stabilized the native structure of whey proteins, provided a desired texture, and slowed the hardening of the model systems. Propylene glycol should not be used in whey protein-based high-protein intermediate-moisture foods because it caused changes in protein conformation and stability as observed by differential scanning calorimeter and Fourier transform infrared spectroscopy and resulted in aggregation of whey proteins and hardening of the bar texture during storage, causing loss in product quality.

  16. Intermediate-Temperature Solid-Oxide Fuel Cells with a Gadolinium-Doped Ceria Anodic Functional Layer Deposited via Radio-Frequency Sputtering.

    PubMed

    Tanveer, Waqas Hassan; Ji, Sanghoon; Yu, Wonjong; Cho, Gu Young; Lee, Yoon Ho; Cha, Suk Won

    2015-11-01

    We investigated the effects of the insertion of a gadolinium-doped ceria (GDC) anodic functional layer (AFL) on the electrochemical performance of intermediate-temperature solid-oxide fuel cells (SOFCs). Fully stabilized yttria-stabilized zirconia (YSZ) was used as an oxygen-ion-conducting and support material. Nickel-Samaria-doped ceriathin film was used as an anode material, while screen-printed lanthanum strontium magnetite served as a cathode material. In order to enhance the interfacial reaction on the anode side, a GDC-AFL with a thickness of about 140 nm, deposited via radio-frequency sputtering, was inserted into the anode-electrolyte interface. SOFCs with and without a GDC-AFL were electrochemically characterized. In an intermediate temperature range of about 700 - 800 degrees C, the application of the GDC-AFL led to an increase in the peak power density of approximately 16%.

  17. Prediction of vibrational frequencies of possible intermediates and side products of the methanol synthesis on ZnO(000overline{1}) by ab initio calculations

    NASA Astrophysics Data System (ADS)

    Koßmann, Jörg; Roßmüller, Guido; Hättig, Christof

    2012-01-01

    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(000overline{1}) surface. Our investigations are based upon our previous work on possible reaction pathways and activation barriers for this reaction at oxygen vacancies on ZnO(000overline{1}). 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 CO2 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.

  18. 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.

  19. 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.

  20. 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.

  1. Stability of A Coevolving Host-parasite System Peaks at Intermediate Productivity

    PubMed Central

    Zhao, Xin-Feng; Hao, Yi-Qi; Zhang, Quan-Guo

    2017-01-01

    Habitat productivity may affect the stability of consumer-resource systems, through both ecological and evolutionary mechanisms. We hypothesize that coevolving consumer-resource systems show more stable dynamics at intermediate resource availability, while very low-level resource supply cannot support sufficiently large populations of resource and consumer species to avoid stochastic extinction, and extremely resource-rich environments may promote escalatory arms-race-like coevolution that can cause strong fluctuations in species abundance and even extinction of one or both trophic levels. We tested these ideas by carrying out an experimental evolution study with a model bacterium-phage system (Pseudomonas fluorescens SBW25 and its phage SBW25Φ2). Consistent with our hypothesis, this system was most stable at intermediate resource supply (fewer extinction events and smaller magnitude of population fluctuation). In our experiment, the rate of coevolution between bacterial resistance and phage infectivity was correlated with the magnitude of population fluctuation, which may explain the different in stability between levels of resource supply. Crucially, our results are consistent with a suggestion that, among the two major modes of antagonistic coevolution, arms race is more likely than fluctuation selection dynamics to cause extinction events in consumer-resource systems. This study suggests an important role of environment-dependent coevolutionary dynamics for the stability of consumer-resource species systems, therefore highlights the importance to consider contemporaneous evolutionary dynamics when studying the stability of ecosystems, particularly those under environmental changes. PMID:28076419

  2. Uv Imaging of Intermediate-Age Magellanic Cloud Clusters: Hot Stellar Populations in Composite Stellar Systems

    NASA Astrophysics Data System (ADS)

    Freedman, Wendy

    1994-01-01

    Hot stars were first recognized to be an important component of galactic spheroids with early vacuum ultraviolet observations of ellipticals and spiral bulges that were made with OAO. Now, 20 years later, we still do not have a full understanding of the VUV evolution of intermediate and old age stellar populations. Using the WFPC2, we therefore propose to undertake an ultraviolet survey of a sample of star clusters spanning a range in age in the Large Magellanic Cloud. The objective of this investigation is to determine the nature of the hot stellar components in rich, intermediate-to-old age LMC clusters. Ground-based optical/IR studies suggest the presence of short-lived hot horizontal branch and post-asymptotic giant branch stars in these clusters but detailed characterizations of the stars require the ultraviolet capability of HST. In this effort we will be aided by the absence of red leaks in the WFPC2 Woods filter and very high angular resolution of the HST. Although old star clusters in the Galaxy and M31 are, and will be, the subjects of intense investigation by HST, OUR SURVEY WILL BE THE FIRST OF ITS KIND FOR POPULATIONS OF INTERMEDIATE AGE. Such systems are critical for interpreting the spectra and colors of high redshift galaxies, and will provide important support to these studies.

  3. 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.

  4. A novel low-noise linear-in-dB intermediate frequency variable-gain amplifier for DRM/DAB tuners

    NASA Astrophysics Data System (ADS)

    Keping, Wang; Zhigong, Wang; Jianzheng, Zhou; Xuemei, Lei; Mingzhu, Zhou

    2009-03-01

    A broadband CMOS intermediate frequency (IF) variable-gain amplifier (VGA) for DRM/DAB tuners is presented. The VGA comprises two cascaded stages: one is for noise-canceling and another is for signal-summing. The chip is fabricated in a standard 0.18 μm 1P6M RF CMOS process of SMIC. Measured results show a good linear-in-dB gain characteristic in 28 dB dynamic gain range of -10 to 18 dB. It can operate in the frequency range of 30-700 MHz and consumes 27 mW at 1.8 V supply with the on-chip test buffer. The minimum noise figure is only 3.1 dB at maximum gain and the input-referred 1 dB gain compression point at the minimum gain is -3.9 dBm.

  5. 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.

  6. 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.

  7. Frequency-Specific Neural Signatures of Spontaneous Low-Frequency Resting State Fluctuations in Psychosis: Evidence From Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) Consortium

    PubMed Central

    Meda, Shashwath A.; Wang, Zheng; Ivleva, Elena I.; Poudyal, Gaurav; Keshavan, Matcheri S.; Tamminga, Carol A.; Sweeney, John A.; Clementz, Brett A.; Schretlen, David J.; Calhoun, Vincent D.; Lui, Su; Damaraju, Eswar; Pearlson, Godfrey D.

    2015-01-01

    Background: We quantified frequency-specific, absolute, and fractional amplitude of low-frequency fluctuations (ALFF/fALFF) across the schizophrenia (SZ)-psychotic bipolar disorder (PBP) psychosis spectrum using resting functional magnetic resonance imaging data from the large BSNIP family study. Methods: We assessed 242 healthy controls (HC), 547 probands (180 PBP, 220 SZ, and 147 schizoaffective disorder—SAD), and 410 of their first-degree relatives (134 PBPR, 150SZR, and 126 SADR). Following standard preprocessing in statistical parametric mapping (SPM8), we computed absolute and fractional power (ALFF/fALFF) in 2 low-frequency bands: slow-5 (0.01–0.027 Hz) and slow-4 (0.027–0.073 Hz). We evaluated voxelwise post hoc differences across traditional Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnostic categories. Results: Across ALFF/fALFF, in contrast to HC, BP/SAD showed hypoactivation in frontal/anterior brain regions in the slow-5 band and hypoactivation in posterior brain regions in the slow-4 band. SZ showed consistent hypoactivation in precuneus/cuneus and posterior cingulate across both bands and indices. Increased ALFF/fALFF was noted predominantly in deep subcortical and temporal structures across probands in both bands and indices. Across probands, spatial ALFF/fALFF differences in SAD resembled PBP more than SZ. None of these ALFF/fALFF differences were detected in relatives. Conclusions: Results suggest ALFF/fALFF is a putative biomarker rather than a familial endophenotype. Overall sensitivity to discriminate proband brain alteration was stronger for fALFF than ALFF. Patterns of differences noted in SAD were more similar to those observed in PBP. Differential effects were noted across the 2 frequency bands, more prominently for BP/SAD compared with SZ, suggesting frequency-sensitive physiologic mechanisms for the former. PMID:26012519

  8. 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.

  9. 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.

  10. 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.

  11. B-Factory Intermediate DC Magnet Power Systems Reliability Modeling and Results

    SciTech Connect

    Bellomo, Paul

    2001-05-24

    The B-Factory is a high-energy physics facility for studying matter versus anti-matter asymmetry. It utilizes 200 Intermediate DC power systems, employing 2.5 to 17kW switchmode converters, to supply beam-shaping magnets with regulated current. Redundancy and modularity were considered to maximize reliability and minimize mean time to replace (MTTR), within technical limitations and cost constraints. Described are the configurations that were considered and reliability prediction models. The SLAC decision to employ a single converter was sound. However, 2 years of operation have confirmed that converter reliability must be improved.

  12. Frequency-Specific Neural Signatures of Spontaneous Low-Frequency Resting State Fluctuations in Psychosis: Evidence From Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) Consortium.

    PubMed

    Meda, Shashwath A; Wang, Zheng; Ivleva, Elena I; Poudyal, Gaurav; Keshavan, Matcheri S; Tamminga, Carol A; Sweeney, John A; Clementz, Brett A; Schretlen, David J; Calhoun, Vincent D; Lui, Su; Damaraju, Eswar; Pearlson, Godfrey D

    2015-11-01

    We quantified frequency-specific, absolute, and fractional amplitude of low-frequency fluctuations (ALFF/fALFF) across the schizophrenia (SZ)-psychotic bipolar disorder (PBP) psychosis spectrum using resting functional magnetic resonance imaging data from the large BSNIP family study. We assessed 242 healthy controls (HC), 547 probands (180 PBP, 220 SZ, and 147 schizoaffective disorder-SAD), and 410 of their first-degree relatives (134 PBPR, 150SZR, and 126 SADR). Following standard preprocessing in statistical parametric mapping (SPM8), we computed absolute and fractional power (ALFF/fALFF) in 2 low-frequency bands: slow-5 (0.01-0.027 Hz) and slow-4 (0.027-0.073 Hz). We evaluated voxelwise post hoc differences across traditional Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnostic categories. Across ALFF/fALFF, in contrast to HC, BP/SAD showed hypoactivation in frontal/anterior brain regions in the slow-5 band and hypoactivation in posterior brain regions in the slow-4 band. SZ showed consistent hypoactivation in precuneus/cuneus and posterior cingulate across both bands and indices. Increased ALFF/fALFF was noted predominantly in deep subcortical and temporal structures across probands in both bands and indices. Across probands, spatial ALFF/fALFF differences in SAD resembled PBP more than SZ. None of these ALFF/fALFF differences were detected in relatives. Results suggest ALFF/fALFF is a putative biomarker rather than a familial endophenotype. Overall sensitivity to discriminate proband brain alteration was stronger for fALFF than ALFF. Patterns of differences noted in SAD were more similar to those observed in PBP. Differential effects were noted across the 2 frequency bands, more prominently for BP/SAD compared with SZ, suggesting frequency-sensitive physiologic mechanisms for the former. © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For

  13. Establishing the Intermediate Unit.

    ERIC Educational Resources Information Center

    Pennsylvania State Dept. of Education, Harrisburg.

    The State of Pennsylvania Act 102 establishes a system of 29 intermediate units, creates intermediate unit boards of directors, spells out their duties and functions, and provides a system of financing their operations. This handbook has been prepared by the Pennsylvania Department of Education to provide intermediate unit boards of directors,…

  14. A DOUBLE PLANETARY SYSTEM AROUND THE EVOLVED INTERMEDIATE-MASS STAR HD 4732

    SciTech Connect

    Sato, Bun'ei; Omiya, Masashi; Harakawa, Hiroki; Nagasawa, Makiko; Ida, Shigeru; Wittenmyer, Robert A.; Izumiura, Hideyuki; Kambe, Eiji; Takeda, Yoichi; Kokubo, Eiichiro; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu

    2013-01-01

    We report the detection of a double planetary system orbiting around the evolved intermediate-mass star HD 4732 from precise Doppler measurements at Okayama Astrophysical Observatory and Australian Astronomical Observatory. The star is a K0 subgiant with a mass of 1.7 M {sub Sun} and solar metallicity. The planetary system is composed of two giant planets with minimum mass of msin i = 2.4 M {sub J}, orbital period of 360.2 days and 2732 days, and eccentricity of 0.13 and 0.23, respectively. Based on dynamical stability analysis for the system, we set the upper limit on the mass of the planets to be about 28 M {sub J} (i > 5 Degree-Sign ) in the case of coplanar prograde configuration.

  15. 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.

  16. Reprocessing the Hipparcos Intermediate Astrometric Data of spectroscopic binaries. II. Systems with a giant component

    NASA Astrophysics Data System (ADS)

    Pourbaix, D.; Boffin, H. M. J.

    2003-02-01

    By reanalyzing the Hipparcos Intermediate Astrometric Data of a large sample of spectroscopic binaries containing a giant, we obtain a sample of 29 systems fulfilling a carefully derived set of constraints and hence for which we can derive an accurate orbital solution. Of these, one is a double-lined spectroscopic binary and six were not listed in the DMSA/O section of the catalogue. Using our solutions, we derive the masses of the components in these systems and statistically analyze them. We also briefly discuss each system individually. Based on observations from the Hipparcos astrometric satellite operated by the European Space Agency (ESA 1997) and on data collected with the Simbad database.

  17. Tracking and Data Relay Satellite System (TDRSS) frequency plan

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The functions of the Tracking and Data Relay Satellite System (TDRSS) are discussed. The primary purpose of the system is to transmit signals to and receive signals from earth orbiting user spacecraft, and provide data from which user spacecraft ephemerides can be calculated. The system configuration is described and illustrated. The frequency plan is analyzed to show the frequency coverage and the signal handling capability of the system. The characteristics of the components of the system are tabulated.

  18. Cost-effectiveness of fluocinolone acetonide implant versus systemic therapy for noninfectious intermediate, posterior, and panuveitis.

    PubMed

    Sugar, Elizabeth A; Holbrook, Janet T; Kempen, John H; Burke, Alyce E; Drye, Lea T; Thorne, Jennifer E; Louis, Thomas A; Jabs, Douglas A; Altaweel, Michael M; Frick, Kevin D

    2014-10-01

    To evaluate the 3-year incremental cost-effectiveness of fluocinolone acetonide implant versus systemic therapy for the treatment of noninfectious intermediate, posterior, and panuveitis. Randomized, controlled, clinical trial. Patients with active or recently active intermediate, posterior, or panuveitis enrolled in the Multicenter Uveitis Steroid Treatment Trial. Data on cost and health utility during 3 years after randomization were evaluated at 6-month intervals. Analyses were stratified by disease laterality at randomization (31 unilateral vs 224 bilateral) because of the large upfront cost of the implant. The primary outcome was the incremental cost-effectiveness ratio (ICER) over 3 years: the ratio of the difference in cost (in United States dollars) to the difference in quality-adjusted life-years (QALYs). Costs of medications, surgeries, hospitalizations, and regular procedures (e.g., laboratory monitoring for systemic therapy) were included. We computed QALYs as a weighted average of EQ-5D scores over 3 years of follow-up. The ICER at 3 years was $297,800/QALY for bilateral disease, driven by the high cost of implant therapy (difference implant - systemic [Δ]: $16,900; P < 0.001) and the modest gains in QALYs (Δ = 0.057; P = 0.22). The probability of the ICER being cost-effective at thresholds of $50,000/QALY and $100,000/QALY was 0.003 and 0.04, respectively. The ICER for unilateral disease was more favorable, namely, $41,200/QALY at 3 years, because of a smaller difference in cost between the 2 therapies (Δ = $5300; P = 0.44) and a larger benefit in QALYs with the implant (Δ = 0.130; P = 0.12). The probability of the ICER being cost-effective at thresholds of $50,000/QALY and $100,000/QALY was 0.53 and 0.74, respectively. Fluocinolone acetonide implant therapy was reasonably cost-effective compared with systemic therapy for individuals with unilateral intermediate, posterior, or panuveitis but not for those with bilateral disease. These results do

  19. Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size.

    PubMed

    Rodríguez, Sara M; Valdivia, Nelson

    2017-01-01

    Parasites are essential components of natural communities, but the factors that generate skewed distributions of parasite occurrences and abundances across host populations are not well understood. Here, we analyse at a seascape scale the spatiotemporal relationships of parasite exposure and host body-size with the proportion of infected hosts (i.e., prevalence) and aggregation of parasite burden across ca. 150 km of the coast and over 22 months. We predicted that the effects of parasite exposure on prevalence and aggregation are dependent on host body-sizes. We used an indirect host-parasite interaction in which migratory seagulls, sandy-shore molecrabs, and an acanthocephalan worm constitute the definitive hosts, intermediate hosts, and endoparasite, respectively. In such complex systems, increments in the abundance of definitive hosts imply increments in intermediate hosts' exposure to the parasite's dispersive stages. Linear mixed-effects models showed a significant, albeit highly variable, positive relationship between seagull density and prevalence. This relationship was stronger for small (cephalothorax length >15 mm) than large molecrabs (<15 mm). Independently of seagull density, large molecrabs carried significantly more parasites than small molecrabs. The analysis of the variance-to-mean ratio of per capita parasite burden showed no relationship between seagull density and mean parasite aggregation across host populations. However, the amount of unexplained variability in aggregation was strikingly higher in larger than smaller intermediate hosts. This unexplained variability was driven by a decrease in the mean-variance scaling in heavily infected large molecrabs. These results show complex interdependencies between extrinsic and intrinsic population attributes on the structure of host-parasite interactions. We suggest that parasite accumulation-a characteristic of indirect host-parasite interactions-and subsequent increasing mortality rates over

  20. Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size

    PubMed Central

    2017-01-01

    Background Parasites are essential components of natural communities, but the factors that generate skewed distributions of parasite occurrences and abundances across host populations are not well understood. Methods Here, we analyse at a seascape scale the spatiotemporal relationships of parasite exposure and host body-size with the proportion of infected hosts (i.e., prevalence) and aggregation of parasite burden across ca. 150 km of the coast and over 22 months. We predicted that the effects of parasite exposure on prevalence and aggregation are dependent on host body-sizes. We used an indirect host-parasite interaction in which migratory seagulls, sandy-shore molecrabs, and an acanthocephalan worm constitute the definitive hosts, intermediate hosts, and endoparasite, respectively. In such complex systems, increments in the abundance of definitive hosts imply increments in intermediate hosts’ exposure to the parasite’s dispersive stages. Results Linear mixed-effects models showed a significant, albeit highly variable, positive relationship between seagull density and prevalence. This relationship was stronger for small (cephalothorax length >15 mm) than large molecrabs (<15 mm). Independently of seagull density, large molecrabs carried significantly more parasites than small molecrabs. The analysis of the variance-to-mean ratio of per capita parasite burden showed no relationship between seagull density and mean parasite aggregation across host populations. However, the amount of unexplained variability in aggregation was strikingly higher in larger than smaller intermediate hosts. This unexplained variability was driven by a decrease in the mean-variance scaling in heavily infected large molecrabs. Conclusions These results show complex interdependencies between extrinsic and intrinsic population attributes on the structure of host-parasite interactions. We suggest that parasite accumulation—a characteristic of indirect host-parasite interactions

  1. DSN frequency and timing system, Mark 4-85

    NASA Technical Reports Server (NTRS)

    Falin, B. W.

    1985-01-01

    As part of the Deep Space Network (DSN) Mark IVA implementation program, the DSN frequency and timing system is currently undergoing changes. With the implementation of signal processing centers (SPC) at each deep space communications complex (DSCC), major changes to the frequency and timing distribution equipment were necessary. A functional description of the Mark IVA frequency and timing system (FTS) as it exists today and planned capabilities through 1988 is given.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Optimized design of recycle chromatography to isolate intermediate retained solutes in ternary mixtures: Langmuir isotherm systems.

    PubMed

    Lee, Ju Weon; Wankat, Phillip C

    2009-10-09

    Batch chromatography with a recycle stream is a popular and simple technique to separate a single target component in a complex mixture with moderate operating conditions. Design of recycle chromatography depends on the retention behaviors of the mixture components. In this work, four nucleosides were considered as solutes. Feed concentration and recycle methods were optimized to isolate only the intermediate retained solute in ternary and pseudo-ternary mixtures. Two recycle methods introduced in our previous work for linear isotherms, the desorbent and feed recycle methods, were compared in terms of productivity and desorbent to feed ratio, D/F, with various feed concentrations for competitive Langmuir isotherm systems. The simulation results show that the target (intermediate retained solute) was separated with over 99.76% purity and 99.88% yield. Productivity of the feed recycle method was increased by up to 162% and D/F was decreased by up to 59% compared to the desorbent recycle method. For the separation of nucleosides, recycle chromatography was compared to eight column simulated moving bed (SMB) cascades with a recycle stream and D/F of the SMB cascades was 58% lower than D/F of recycle chromatography at the same productivity. However, recycle chromatography is much simpler.

  8. Validation and modification of a proposed substaging system for patients with intermediate hepatocellular carcinoma.

    PubMed

    Wang, Jing-Houng; Kee, Kwong-Ming; Lin, Chih-Yun; Hung, Chao-Hung; Chen, Chien-Hung; Lee, Chuan-Mo; Lu, Sheng-Nan

    2015-02-01

    Based on up-to-seven criteria and Child-Pugh score, four substages of Barcelona Clinic Liver Cancer (BCLC) intermediate hepatocellular carcinoma (HCC) were proposed. The purpose of this study was to validate and modify this proposal. Between January 2002 and February 2011, newly diagnosed intermediate HCC patients underwent transarterial embolization (TAE) were enrolled. Patients were stratified into four (B1-B4) substages and followed up until death or end of 2012. Patients' survivals and discriminatory ability of substaging systems were compared. Five-hundred and eighty patients were enrolled. There were 56.6%, 33.8%, 7.4%, and 2.2% in substage B1, B2, B3, and B4. The 5-year survival rate was 21.4%, 13.9%, 7.4%, and 7.7% with median survival time of 2.4, 1.3, 0.5, and 0.8 years (P < 0.001). In addition to substage B1-B4, α-fetoprotein (AFP) level was an independent factor associated with survival in multivariate analysis. According to AFP < or > 200 ng/mL, B1 was classified into B1a and B1b, and B2 into B2a and B2b. There were no differences in survivals between B1b and B2a (P = 0.174), and B2b and B3 (P = 0.785). Patients were re-classified into modified (m)B1 (B1a), mB2 (B1b + B2a), mB3 (B2b + B3). The modified substages (mB1-mB3) showed a more desirable substaging system. For BCLC intermediate HCC patients, substages B1-B4 were useful in predicting survival after TAE. However, modified substaging system provided better prognostic prediction. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  9. 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.

  10. High fidelity quantum state transfer in electromechanical systems with intermediate coupling

    PubMed Central

    Zhou, Jian; Hu, Yong; Yin, Zhang-qi; Wang, Z. D.; Zhu, Shi-Liang; Xue, Zheng-Yuan

    2014-01-01

    Hybrid quantum systems usually consist of two or more subsystems, which may take the advantages of the different systems. Recently, the hybrid system consisting of circuit electromechanical subsystems have attracted great attention due to its advanced fabrication and scalable integrated photonic circuit techniques. Here, we propose a scheme for high fidelity quantum state transfer between a superconducting qubit and a nitrogen-vacancy center in diamond, which are coupled to a superconducting transmission-line resonator with coupling strength g1 and a nanomechanical resonator with coupling strength g2, respectively. Meanwhile, the two resonators are parametrically coupled with coupling strength J. The system dynamics, including the decoherence effects, is numerical investigated. It is found that both the small () and large () coupling regimes of this hybrid system can not support high fidelity quantum state transfer before significant technique advances. However, in the intermediate coupling regime (J ~ g1 ~ g2), in contrast to a conventional wisdom, high fidelity quantum information transfer can be implemented, providing a promising route towards high fidelity quantum state transfer in similar coupled resonators systems. PMID:25168206

  11. High fidelity quantum state transfer in electromechanical systems with intermediate coupling.

    PubMed

    Zhou, Jian; Hu, Yong; Yin, Zhang-qi; Wang, Z D; Zhu, Shi-Liang; Xue, Zheng-Yuan

    2014-08-29

    Hybrid quantum systems usually consist of two or more subsystems, which may take the advantages of the different systems. Recently, the hybrid system consisting of circuit electromechanical subsystems have attracted great attention due to its advanced fabrication and scalable integrated photonic circuit techniques. Here, we propose a scheme for high fidelity quantum state transfer between a superconducting qubit and a nitrogen-vacancy center in diamond, which are coupled to a superconducting transmission-line resonator with coupling strength g1 and a nanomechanical resonator with coupling strength g2, respectively. Meanwhile, the two resonators are parametrically coupled with coupling strength J. The system dynamics, including the decoherence effects, is numerical investigated. It is found that both the small (J<{g1,g2}) and large (J>{g1,g2}) coupling regimes of this hybrid system can not support high fidelity quantum state transfer before significant technique advances. However, in the intermediate coupling regime (J ~ g1 ~ g2), in contrast to a conventional wisdom, high fidelity quantum information transfer can be implemented, providing a promising route towards high fidelity quantum state transfer in similar coupled resonators systems.

  12. 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.

  13. 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.

  14. Value of PV systems experiments. Volume 1: A preliminary assessment of the lessons learned from nine intermediate-size systems

    NASA Astrophysics Data System (ADS)

    Thomas, M.

    1984-08-01

    Nine intermediate-size photovoltaic (PV) experiments sponsored by the US Department of Energy (DOE) are reviewed. Five variations of PV technology were represented in the experiments: (1) flat plate; (2) flat plate with mirror enhancement; (3) combined photovoltaic/thermal (PV/T) parabolic trough concentrator; (4) combined line-focus Fresnel lens concentrator and thermal; and (5) point-focus Fresnel lens concentrator. The system costs and installation costs are reviewed. The characteristics and electrical performance of the systems are described. Operation and maintenance data are given.

  15. Value of PV systems experiments. Volume I. A preliminary assessment of the lessons learned from nine intermediate-size systems

    SciTech Connect

    Thomas, M.

    1984-08-01

    This report reviews nine intermediate-size photovoltaic (PV) experiments sponsored by the US Department of Energy (DOE). Five variations of PV technology were represented in the experiments: (1) flat plate; (2) flat plate with mirror enhancement; (3) combined photovoltaic/thermal (PV/T) parabolic trough concentrator; (4) combined line-focus Fresnel lens concentrator and thermal; and (5) point-focus Fresnel lens concentrator. The system costs and installation costs are reviewed. The characteristics and electrical performance of the systems are described. Operation and maintenance data are given.

  16. 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

    As the data rates required for digitally encoded television are reduced, satellite systems employing the transmission of digitally encoded television will become attractive. It is likely that television transmitted in this format will be adjacent to or in the same frequency band as television transmissions in other modulation formats, so a knowledge of carrier to interference power ratios as a function of assessed picture quality will be required for frequency sharing between these different modulation formats. This paper presents the results 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.

  17. 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.

  18. Frequency Measurement System of Optical Clocks Without a Flywheel Oscillator.

    PubMed

    Fujieda, Miho; Ido, Tetsuya; Hachisu, Hidekazu; Gotoh, Tadahiro; Takiguchi, Hiroshi; Hayasaka, Kazuhiro; Toyoda, Kenji; Yonegaki, Kenji; Tanaka, Utako; Urabe, Shinji

    2016-12-01

    We developed a system for the remote frequency comparison of optical clocks. The system does not require a flywheel oscillator at the remote end, making it possible to evaluate optical frequencies even in laboratories, where no stable microwave reference, such as an Rb clock, a Cs clock, or a hydrogen maser exists. The system is established by the integration of several systems: a portable carrier-phase two-way satellite frequency transfer station and a microwave signal generation system by an optical frequency comb from an optical clock. The measurement was as quick as a conventional method that employs a local microwave reference. We confirmed the system uncertainty and instability to be at the low 10(-15) level using an Sr lattice clock.

  19. Telemetry Systems Radio Frequency (RF) Handbook

    DTIC Science & Technology

    2001-12-01

    1-11 Figure 1-9. OQPSK block diagram...space OQPSK offset quadrature phase-shift keying p-p peak-to-peak PAM pulse-amplitude modulation PCM pulse-code modulation PLD path length difference...11 Figure 1-8. QPSK block diagram. 1.3.2.2.3 Offset Quadrature Phase-Shift Keying ( OQPSK ) Systems. The OQPSK transmission system, also known as

  20. 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.

  1. Beat frequency ultrasonic microsphere contrast agent detection system

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  2. 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.

  3. Intermediate frequency magnetic fields generated by an induction heating (IH) cooktop do not affect genotoxicities and expression of heat shock proteins.

    PubMed

    Sakurai, Tomonori; Kiyokawa, Tomoko; Kikuchi, Kazuki; Miyakoshi, Junji

    2009-01-01

    The aim of this study is to evaluate the effects of intermediate frequency (IF) fields generated by induction heating (IH) cooktops from the perspective of cellular genotoxicity and stress responses. We evaluated the effects of exposure to 23 kHz magnetic fields at 6.05 mT(rms) for 2 h on cellular genotoxicity and stress responses in vitro. The maximum output power in most IH cooktops is at this frequency. The magnetic flux density is approximately 1000 times higher than the reference level in the International Commission on Non-ionising Radiation Protection (ICNIRP) guidelines. For assessment of genotoxicity, we studied cell growth, comet assay, micronucleus formation and hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation. Heat shock protein (Hsp) 27, 70, 105 and phosphorylated Hsp27 were evaluated as indicators of the stress responses. We did not detect any effects of the IF magnetic fields on cell growth, comet assay, micronucleus formation, HPRT gene mutation, expression of phosphorylated Hsp27, or nuclear translocation of Hsp27, 70 or 105. Our results indicate that exposure to an IF magnetic field at 6.05 mT(rms) for 2 h does not cause detectable cellular genotoxicity, and does not induce detectable cellular stress.

  4. Battery Performance in Frequency Modulated Amplification Systems.

    ERIC Educational Resources Information Center

    Lyon, David J.; Swain, Graeme D.

    1989-01-01

    This paper investigates one characteristic of FM radio hearing-aid systems as used in the education of hearing impaired children: battery performance. While batteries studied performed according to manufacturer's specifications, the importance of monitoring the charging procedure cannot be overemphasized. (Author/PB)

  5. Variable association of reactive intermediate genes with systemic lupus erythematosus in populations with different African ancestry.

    PubMed

    Ramos, Paula S; Oates, James C; Kamen, Diane L; Williams, Adrienne H; Gaffney, Patrick M; Kelly, Jennifer A; Kaufman, Kenneth M; Kimberly, Robert P; Niewold, Timothy B; Jacob, Chaim O; Tsao, Betty P; Alarcón, Graciela S; Brown, Elizabeth E; Edberg, Jeffrey C; Petri, Michelle A; Ramsey-Goldman, Rosalind; Reveille, John D; Vilá, Luis M; James, Judith A; Guthridge, Joel M; Merrill, Joan T; Boackle, Susan A; Freedman, Barry I; Scofield, R Hal; Stevens, Anne M; Vyse, Timothy J; Criswell, Lindsey A; Moser, Kathy L; Alarcón-Riquelme, Marta E; Langefeld, Carl D; Harley, John B; Gilkeson, Gary S

    2013-06-01

    Little is known about the genetic etiology of systemic lupus erythematosus (SLE) in individuals of African ancestry, despite its higher prevalence and greater disease severity. Overproduction of nitric oxide (NO) and reactive oxygen species are implicated in the pathogenesis and severity of SLE, making NO synthases and other reactive intermediate-related genes biological candidates for disease susceptibility. We analyzed variation in reactive intermediate genes for association with SLE in 2 populations with African ancestry. A total of 244 single-nucleotide polymorphisms (SNP) from 53 regions were analyzed in non-Gullah African Americans (AA; 1432 cases and 1687 controls) and the genetically more homogeneous Gullah of the Sea Islands of South Carolina (133 cases and 112 controls). Single-marker, haplotype, and 2-locus interaction tests were computed for these populations. The glutathione reductase gene GSR (rs2253409; p = 0.0014, OR 1.26, 95% CI 1.09-1.44) was the most significant single SNP association in AA. In the Gullah, the NADH dehydrogenase NDUFS4 (rs381575; p = 0.0065, OR 2.10, 95% CI 1.23-3.59) and NO synthase gene NOS1 (rs561712; p = 0.0072, OR 0.62, 95% CI 0.44-0.88) were most strongly associated with SLE. When both populations were analyzed together, GSR remained the most significant effect (rs2253409; p = 0.00072, OR 1.26, 95% CI 1.10-1.44). Haplotype and 2-locus interaction analyses also uncovered different loci in each population. These results suggest distinct patterns of association with SLE in African-derived populations; specific loci may be more strongly associated within select population groups.

  6. 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.

  7. Frequency weighted system identification and linear quadratic controller design

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Phan, Minh; Juang, Jer-Nan; Longman, Richard W.; Sulla, Jeffrey L.

    1991-01-01

    Application of filters for frequency weighting of Markov parameters (pulse response functions) is described in relation to system/observer identification. The time domain identification approach recovers a model which has a pulse response weighted according to frequency. The identified model is composed of the original system and filters. The augmented system is in a form which can be used directly for frequency weighted linear quadratic controller design. Data from either single or multiple experiments can be used to recover the Markov parameters. Measured acceleration signals from a truss structure are used for system identification and the model obtained is used for frequency weighted controller design. The procedure makes the identification and controler design complementary problems.

  8. 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

  9. 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

  10. Spectroscopic Investigation of Materials for Frequency Agile Laser Systems.

    DTIC Science & Technology

    1985-01-01

    fluorescence spectra and lifetimes of divalent Rh, Ru, Pt, and Ir ions in alkali halide crystals are measured using pulsed nitrogen laser excitation...AD-Ai5t 73t SPECTROSCOPIC INVESTIGRTION OF MATERIALS FOR FREQUENCY t/ AGILE LASER SYSTEMS(U) OKLAHOMA STATE UNIV STILLWATER DEPT OF PHYSICS R C...INVESTIGATION OF MATERIALS FOR FREQUENCY AGILE LASER SYSTEMS Richard C. Powell, Ph.D. Principal Investigator Department of Physics OKLAHOMA STATE UNIVERSITY

  11. Intermediate treatments

    Treesearch

    John R. Jones; Wayne D. Shepperd

    1985-01-01

    Intermediate treatments are those applied after a new stand is successfully established and before the final harvest. These include not only intermediate cuttings - primarily thinning - but also fertilization, irrigation, and protection of the stand from damaging agents.

  12. A frequency-routed satellite system concept using multiple orthogonally-polarized beams for frequency reuse

    NASA Technical Reports Server (NTRS)

    Rotholz, E.; White, B. E.

    1983-01-01

    The design concepts of a multibeam frequency-division multiplexed satellite system accessed by many moderately sized earth stations are outlined. In the system proposed here, traffic is routed from beam to beam through appropriate apportionment and filtering. Within a beam, the routing to particular users is achieved by conventional FDM. The optimum beam size, beam isolation, orthogonal polarization assignment to beams, the concept of beam groups yielding a simple transponder design, and the establishment of a frequency plan providing interference-free band assignments are discussed.

  13. Microwave photonic system for instantaneous frequency measurement based on principles of "frequency-amplitude" conversion in fiber Bragg grating and additional frequency separation

    NASA Astrophysics Data System (ADS)

    Ivanov, Alexander A.; Morozov, Oleg G.; Andreev, Vladimir A.; Morozov, Gennady A.; Kuznetsov, Artem A.; Faskhutdinov, Lenar M.

    2017-04-01

    This article describes the design principles of optoelectronic system (OES) for instantaneous frequency measurement (IFM) of microwave signals based on the use of amplitude-phase modulation conversion of single optical carrier into symmetrical dual-frequency signal for additional frequency separation, its modulation by unknown frequency and subsequent "frequency-amplitude" measurement conversion in Fiber Bragg Grating (FBG) with Gaussian reflection profile. Such approach allows increasing of measurement resolution at low frequencies.

  14. 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}.

  15. Intermediately complex models for the hydrological interactions in the atmosphere-vegetation-soil system

    NASA Astrophysics Data System (ADS)

    Zeng, X. D.; Wang, A. H.; Zeng, Q. C.; Dickinson, R. E.; Zeng, X. B.; Shen, S. S. P.

    2006-01-01

    This paper investigates the hydrological interactions in the atmosphere-evegetation-soil system by using the bucket model and several new simplified intermediately complex models. The results of mathematical analysis and numerical simulations show that these models, despite their simplicity, can very clearly reveal the essential features of the rather complex hydrological system of atmosphere-ecosystem-soil. For given atmospheric variables, these models clearly demonstrate multiple timescales, the "red shift" of response spectra, multi-equilibria and limit cycles, bifurcation, abrupt change, self-organization, recovery, "desertification", and chaos. Most of these agree with observations. Especially, the weakening of "shading effect" of living canopy and the wilted biomass might be a major mechanism leading to the desertification in a relatively short period due to overgrazing, and the desertification in a relatively long period or in climate of change might be due to both Charney's mechanism and the shading effect. These ideas could be validated with further numerical simulations. In the paper, some methods for improving the estimation of timescales in the soil water evolution responding to the forcing are also proposed.

  16. Glial fibrillary acidic protein (GFAP) and the astrocyte intermediate filament system in diseases of the central nervous system.

    PubMed

    Hol, Elly M; Pekny, Milos

    2015-02-01

    Glial fibrillary acidic protein (GFAP) is the hallmark intermediate filament (IF; also known as nanofilament) protein in astrocytes, a main type of glial cells in the central nervous system (CNS). Astrocytes have a range of control and homeostatic functions in health and disease. Astrocytes assume a reactive phenotype in acute CNS trauma, ischemia, and in neurodegenerative diseases. This coincides with an upregulation and rearrangement of the IFs, which form a highly complex system composed of GFAP (10 isoforms), vimentin, synemin, and nestin. We begin to unravel the function of the IF system of astrocytes and in this review we discuss its role as an important crisis-command center coordinating cell responses in situations connected to cellular stress, which is a central component of many neurological diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    Wright, David F.

    1995-05-01

    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.

  18. 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.

  19. Development of III-Sb Quantum Dot Systems for High Efficiency Intermediate Band Solar Cells

    SciTech Connect

    Huffaker, Diana; Hubbard, Seth; Norman, Andrew

    2015-07-31

    This project aimed to develop solar cells that can help reduce cost per watt. This work focused on developing solar cells that utilize quantum dot (QD) nanomaterials to provide multijunction solar cell efficiency at the cost of single junction solar cell. We focused on a novel concept known as intermediate band solar cells (IBSC) where an additional energy band is inserted in a single solar cell to accommodate sub-bandgap photons absorption which otherwise are lost through transmission. The additional energy band can be achieved by growing QDs within a solar cell p-n junction. Though numerous studies have been conducted to develop such QD systems, very small improvements in solar energy conversion efficiency have been reported. This is mainly due to non-optimal material parameters such as band gap, band offset etc. In this work, we identified and developed a novel QD material system that meets the requirements of IBSC more closely than the current state-of-the-art technology. To achieve these goals, we focused on three important areas of solar cell design: band structure calculations of new materials, efficient device design for high efficiency, and development of new semiconductor materials. In this project, we focused on III-Sb materials as they possess a wide range of energy bandgaps from 0.2 eV to 2eV. Despite the difficulty involved in realizing these materials, we were successfully developed these materials through a systematic approach. Materials studied in this work are AlAsSb (Aluminum Arsenide Antimonide), InAlAs (Indium Aluminum Arsenide) and InAs (Indium Arsenide). InAs was used to develop QD layers within AlAsSb and InAlAs p-n junctions. As the QDs have very small volume, up to 30 QD layers been inserted into the p-n junction to enhance light absorption. These QD multi-stack devices helped in understanding the challenges associated with the development of quantum dot solar cells. The results from this work show that the quantum dot solar cells indeed

  20. 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

  1. Geographic market suitability analysis for low- and intermediate-temperature solar IPH systems

    SciTech Connect

    Turner, A.K.; Weber, J.C.; DeAngelis, M.

    1981-12-01

    Previous studies of the industrial market for solar energy systems have considered the level of solar radiation as the main determinant of geographic markets in the US. This study evaluates geographical markets extensively based on such criteria as output of different types of low- and intermediate-temperature solar thermal collectors, air quality constraints for competitive fuels, state solar tax incentives, fuel costs, low industrial use of coal, high industrial growth areas, and industry energy consumption in different parts of the US. Market suitability analysis and mapping techniques, refined in the past 20 years by land use planners, were used to evaluate geographical markets. A computer-aided system, Generalized Map Analysis Planning System (GMAPS), performed interactive, cellular, computer mapping, and composite mapping. Results indicate that the US Southwest and West are the most attractive geographical markets for solar IPH, based on an equal weighting of the evaluation criteria. The West North-Central and East South-Central regions appear to have the least attractive markets. Specific areas within states where solar IPH systems have distinct marketing advantages also are apparent from the composite maps. However, when different weights are assigned to the various criteria, the results change significantly for some regions of the country, such as the New England, Mid-Atlantic, and West South-Central 2 regions. The results of this work will become less valid in the future as state incentives for solar IPH, air quality regulations, and the status of competitive fuels all change. Volume I contains study results and maps.

  2. Frequency-difference-dependent stochastic resonance in neural systems

    NASA Astrophysics Data System (ADS)

    Guo, Daqing; Perc, Matjaž; Zhang, Yangsong; Xu, Peng; Yao, Dezhong

    2017-08-01

    Biological neurons receive multiple noisy oscillatory signals, and their dynamical response to the superposition of these signals is of fundamental importance for information processing in the brain. Here we study the response of neural systems to the weak envelope modulation signal, which is superimposed by two periodic signals with different frequencies. We show that stochastic resonance occurs at the beat frequency in neural systems at the single-neuron as well as the population level. The performance of this frequency-difference-dependent stochastic resonance is influenced by both the beat frequency and the two forcing frequencies. Compared to a single neuron, a population of neurons is more efficient in detecting the information carried by the weak envelope modulation signal at the beat frequency. Furthermore, an appropriate fine-tuning of the excitation-inhibition balance can further optimize the response of a neural ensemble to the superimposed signal. Our results thus introduce and provide insights into the generation and modulation mechanism of the frequency-difference-dependent stochastic resonance in neural systems.

  3. High-frequency H-PDLC optical chopper for frequency division multiplexing fluorescence confocal microscope system

    NASA Astrophysics Data System (ADS)

    Jiang, Yanmeng; Zheng, Jihong; Tang, Pingyu; Wang, Tingting; Huang, Aiqin; Zhou, Zengjun; Zhuang, Songlin

    2011-10-01

    The optical chopper array based on Holographic Polymer Dispersed Liquid Crystal (H-PDLC) working at high frequencies, for example 1KHz, 2KHz, and its application in an improved Frequency Division Multiplexed Fluorescence Confocal Microscope (FDMFCM) system are reported in this article. The system is a combination of the confocal microscopy and the frequency division multiplexing technique. Taking advantages of the optical chopper array based on H-PDLC that avoids mechanical movements, the FDMFCM system is able to obtain better Signal-Noise Ratio (SNR), smaller volume, more independent channels and more efficient scanning. What's more, the FDMCFM maintained the high special resolution ability and realized faster temporal resolution than pervious system. Using the proposed device, the FDMFCM system conducts successful parallel detection of rat neural cells. Fluorescence intensity signals from two different points on the specimen, which represent concentration of certain kind of proteins in the sample cells, are achieved. The experimental results show that the proposed H-PDLC optical chopper array has feasibility in FDMFCM system, which owes to its unique characteristics such as fast response, simple fabrication and lower consumption etc. With the development of H-PDLC based devices, there will be prospective in upgrading FDMFCM system's performance in the biomedical area.

  4. Uranium transport experiments at the intermediate scale: Do more heterogeneous systems create more complex behaviors?

    NASA Astrophysics Data System (ADS)

    Miller, A. W.; Rodriguez, D.; Honeyman, B.

    2010-12-01

    With respect to complexity, two things occur as experimental scale increases. The first is that as total system size increases, the heterogeneities at smaller scales are explicitly included while simultaneously allowing for a general increase in total complexity. The second is that model constraining measurements become more difficult to make. Bench scale systems limit total complexity; field scale systems are limited in the amount of characterization that can be completed. Intermediate scale systems can bridge this gap, allowing for increased complexity relative to the bench scale and better characterization ability relative to the field scale. We have completed three intermediate scale experiments with a uranium contaminated sediment from a former uranium mill site near Naturita in southwestern Colorado, USA. Three tanks were packed with various particle size distributions of this sediment. The first two tanks were 2-D in nature and had dimensions of 2.44m x 1.22m x 7.62cm (tank #1, LxHxW), and 2.44m x 0.61m x 7.62cm (tank #2, LxHxW). Tank #3 was 3-D in nature with dimensions of 2.44m x 0.61m x 0.61m (LxHxW). Tank #1 was packed in a homogenous manner with only the <2mm size fraction of sediment. For tank #2 the <2mm fraction was split into <0.250mm and >0.250mm fractions, and these two fractions allowed for a physically heterogeneous packing. Using all three of the previously mentioned size fractions as well as a 0.125-0.250mm and a 4-12mm fraction, tank #3 was also packed in a heterogeneous fashion. The masses of sediment used in the three tanks are: tank #1 ~280kg, tank #2 - 163kg, and tank #3 - 1160kg. Flow through all three systems was comparable, and controlled by constant head boundaries. Three different artificial ground waters (AGW) were used with ionic compositions similar to that found at the field site. The major distinctions are that AGW #1 was in equilibrium with atmospheric CO2 and had no Si; AGW#2 was in equilibrium with 2%CO2 and had no Si; AGW#3

  5. Localization of serotonin in the nervous system of Biomphalaria glabrata, an intermediate host for schistosomiasis.

    PubMed

    Delgado, Nadia; Vallejo, Deborah; Miller, Mark W

    2012-10-01

    The digenetic trematode Schistosoma mansoni that causes the form of schistosomiasis found in the Western Hemisphere requires the freshwater snail Biomphalaria glabrata as its primary intermediate host. It has been proposed that the transition from the free-living S. mansoni miracidium to parasitic mother sporocyst depends on uptake of biogenic amines, e.g. serotonin, from the snail host. However, little is known about potential sources of serotonin in B. glabrata tissues. This investigation examined the localization of serotonin-like immunoreactivity (5HTli) in the central nervous system (CNS) and peripheral tissues of B. glabrata. Emphasis was placed on the cephalic and anterior pedal regions that are commonly the sites of S. mansoni miracidium penetration. The anterior foot and body wall were densely innervated by 5HTli fibers but no peripheral immunoreactive neuronal somata were detected. Within the CNS, clusters of 5HTli neurons were observed in the cerebral, pedal, left parietal, and visceral ganglia, suggesting that the peripheral serotonergic fibers originate from the CNS. Double-labeling experiments (biocytin backfill × serotonin immunoreactivity) of the tentacular nerve and the three major pedal nerves (Pd n. 10, Pd n. 11, and Pd n. 12) disclosed central neurons that project to the cephalopedal periphery. Overall, the central distribution of 5HTli neurons suggests that, as in other gastropods, serotonin regulates the locomotion, reproductive, and feeding systems of Biomphalaria. The projections to the foot and body wall indicate that serotonin may also participate in defensive, nociceptive, or inflammation responses. These observations identify potential sources of host-derived serotonin in this parasite-host system. Inc.

  6. Gamma-ray Excess from a Stacked Sample of High- and Intermediate-frequency Peaked Blazars Observed with the MAGIC Telescope

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Baixeras, C.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Bonnoli, G.; Bordas, P.; Borla Tridon, D.; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Britzger, D.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Commichau, S.; Contreras, J. L.; Cortina, J.; Costado, M. T.; Covino, S.; Dazzi, F.; De Angelis, A.; De Cea del Pozo, E.; De los Reyes, R.; De Lotto, B.; De Maria, M.; De Sabata, F.; Delgado Mendez, C.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Errando, M.; Ferenc, D.; Fonseca, M. V.; Font, L.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Godinovic, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Hsu, C. C.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; La Barbera, A.; Laille, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Lorenz, E.; Majumdar, P.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moles, M.; Moralejo, A.; Nieto, D.; Nilsson, K.; Ninkovic, J.; Orito, R.; Oya, I.; Paiano, S.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pascoli, D.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, L.; Prada, F.; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Struebig, J. C.; Suric, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzic, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.

    2011-03-01

    Between 2004 and 2009, a sample of 28 X-ray selected high- and intermediate-frequency peaked blazars with an X-ray flux larger than 2 μJy at 1 keV in the redshift range from 0.018 to 0.361 was observed with the MAGIC telescope at energies above 100 GeV. Seven among them were detected and the results of these observations are discussed elsewhere. Here we concentrate on the remaining 21 blazars which were not detected during this observation campaign and present the 3σ (99.7%) confidence upper limits on their flux. The individual flux upper limits lie between 1.6% and 13.6% of the integral flux from the Crab Nebula. Applying a stacking method to the sample of non-detections with a total of 394.1 hr exposure time, we find evidence for an excess with a cumulative significance of 4.9 standard deviations. It is not dominated by individual objects or flares, but increases linearly with the observation time as for a constant source with an integral flux level of ~1.5% of that observed from the Crab Nebula above 150 GeV.

  7. Intermediate frequency magnetic field at 23 kHz does not modify gene expression in human fetus-derived astroglia cells.

    PubMed

    Sakurai, Tomonori; Narita, Eijiro; Shinohara, Naoki; Miyakoshi, Junji

    2012-12-01

    The increased use of induction heating (IH) cooktops in Japan and Europe has raised public concern on potential health effects of the magnetic fields generated by IH cooktops. In this study, we evaluated the effects of intermediate frequency (IF) magnetic fields generated by IH cooktops on gene expression profiles. Human fetus-derived astroglia cells were exposed to magnetic fields at 23 kHz and 100 µT(rms) for 2, 4, and 6 h and gene expression profiles in cells were assessed using cDNA microarray. There were no detectable effects of the IF magnetic fields at 23 kHz on the gene expression profile, whereas the heat treatment at 43 °C for 2 h, as a positive control, affected gene expression including inducing heat shock proteins. Principal component analysis and hierarchical analysis showed that the gene profiles of IF-exposed groups were similar to the sham-exposed group and were different than the heat treatment group. These results demonstrated that exposure of human fetus-derived astroglia cells to an IF magnetic field at 23 kHz and 100 µT(rms) for up to 6 h did not induce detectable changes in gene expression profile.

  8. Detection and characterization of spacer integration intermediates in type I-E CRISPR-Cas system.

    PubMed

    Arslan, Zihni; Hermanns, Veronica; Wurm, Reinhild; Wagner, Rolf; Pul, Ümit

    2014-07-01

    The adaptation against foreign nucleic acids by the CRISPR-Cas system (Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated proteins) depends on the insertion of foreign nucleic acid-derived sequences into the CRISPR array as novel spacers by still unknown mechanism. We identified and characterized in Escherichia coli intermediate states of spacer integration and mapped the integration site at the chromosomal CRISPR array in vivo. The results show that the insertion of new spacers occurs by site-specific nicking at both strands of the leader proximal repeat in a staggered way and is accompanied by joining of the resulting 5'-ends of the repeat strands with the 3'-ends of the incoming spacer. This concerted cleavage-ligation reaction depends on the metal-binding center of Cas1 protein and requires the presence of Cas2. By acquisition assays using plasmid-located CRISPR array with mutated repeat sequences, we demonstrate that the primary sequence of the first repeat is crucial for cleavage of the CRISPR array and the ligation of new spacer DNA.

  9. 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.

  10. Detection and characterization of spacer integration intermediates in type I-E CRISPR–Cas system

    PubMed Central

    Arslan, Zihni; Hermanns, Veronica; Wurm, Reinhild; Wagner, Rolf; Pul, Ümit

    2014-01-01

    The adaptation against foreign nucleic acids by the CRISPR–Cas system (Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated proteins) depends on the insertion of foreign nucleic acid-derived sequences into the CRISPR array as novel spacers by still unknown mechanism. We identified and characterized in Escherichia coli intermediate states of spacer integration and mapped the integration site at the chromosomal CRISPR array in vivo. The results show that the insertion of new spacers occurs by site-specific nicking at both strands of the leader proximal repeat in a staggered way and is accompanied by joining of the resulting 5′-ends of the repeat strands with the 3′-ends of the incoming spacer. This concerted cleavage-ligation reaction depends on the metal-binding center of Cas1 protein and requires the presence of Cas2. By acquisition assays using plasmid-located CRISPR array with mutated repeat sequences, we demonstrate that the primary sequence of the first repeat is crucial for cleavage of the CRISPR array and the ligation of new spacer DNA. PMID:24920831

  11. On an application of the intermediate Hamiltonian method for molecular systems

    SciTech Connect

    Seto, R.; Stankevich, I.V.

    1999-04-01

    An application of the intermediate Hamiltonian method is reported in estimation of the lower bounds to the potential energy curve of the hydrogen molecule ion. An improvement of the method and its limitation are also discussed.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. The ONERA Airborne Multi Frequency SAR Imaging Systems (PREPRINT)

    DTIC Science & Technology

    2014-10-09

    The ONERA Airborne Multi-Frequency SAR Imaging Systems Olivier Ruault du Plessis Electromagnetism and Radar Department ONERA Salon de...Provence FRANCE Olivier.Ruault_du_Plessis@onera.fr Philippe Dreuillet Electromagnetism and Radar Department ONERA Palaiseau FRANCE...Philippe.Dreuillet@onera.fr Abstract—RAMSES-NG and SETHI, the airborne SAR systems developed by ONERA , integrate new generation of radar and optronics

  18. Time and frequency transfer system using GNSS receiver

    NASA Astrophysics Data System (ADS)

    Wang, Jia-Lun; Huang, Shi-Yu; Liao, Chia-Shu

    2014-12-01

    Global Positioning System (GPS) time and frequency transfer is one of the most useful ways for the comparison of remote clocks, and the comparison results are very important for the calculation of International Atomic Time and UTC (Coordinated Universal Time). For the timing laboratories, it is necessary to calibrate and periodically evaluate their time transfer system to ensure the accuracy and long-term stability of their time and frequency comparison results. Once the calibration is achieved, it can be used as a standard for traceable time and frequency measurements. In this paper, we demonstrate Global Navigation Satellite System receiver calibration campaign between the National Time and Frequency Standard Laboratory of Telecommunication Laboratories in Taiwan and the Measurement Standards Laboratory in New Zealand. Two calibration strategies, receiver calibration and the link calibration, are adopted in this work. The receiver calibration is used for evaluating the performance of the proposed system in domestic traceability network in Taiwan. The link calibration is used for minimizing the total uncertainty budget in calculating UTC. Experimental results indicate that the expanded time and frequency uncertainty of the proposed system (with a coverage factor of k = 2) are less than 25 ns and 1.1 × 10-13, respectively, after 1 day of averaging. The accuracy of GPS time link is reported to be better than 2 ns in long-baseline link (10,000 km) in Asia-Pacific Zone.

  19. Optical spectroscopy of the microquasar GRS 1758-258: a possible intermediate mass system?

    NASA Astrophysics Data System (ADS)

    Martí, Josep; Luque-Escamilla, Pedro L.; Muñoz-Arjonilla, Álvaro J.

    2016-11-01

    Context. GRS 1758-258 is one of two prototypical microquasars towards the Galactic center direction discovered almost a quarter of a century ago. The system remains poorly studied in the optical domain due to its counterpart being a very faint and absorbed target in a crowded region of the sky. Aims: Our aim is to investigate GRS 1758-258 in order to shed light on the nature of the stellar binary components. In particular, the main physical parameters of the donor star, such as the mass or the spectral type, are not yet well constrained. Methods: GRS 1758-258 has remained so far elusive to optical spectroscopy owing to its observational difficulties. Here, we use this traditional tool of stellar astronomy at low spectral resolution with a 10 m class telescope and a long slit spectrograph. Results: An improved spectrum is obtained as compared to previous work. The quality of the data does not allow the detection of emission or absorption features but, nevertheless, we manage to partially achieve our aims comparing the de-reddened continuum with the spectral energy distribution expected from an irradiated disc model and different donor star templates. Conclusions: We tentatively propose that GRS 1758-258 does not host a giant star companion. Instead, a main sequence star with mid-A spectral type appears to better agree with our data. The main impacts of this finding are the possibility that we are dealing with an intermediate mass system and, in this case, the prediction of an orbital period significantly shorter than previously proposed.

  20. Coding for Frequency - Shift - Keyed (FSK) Communication System

    DTIC Science & Technology

    1973-12-01

    COMMUNICATION SYSTEM ELECTRICAL ENGINEERING DEPARTMENT UNIVERSITY OF MISSOURI TECHNICAL REPORT AFATL-TR-73-245 DECEMBER 1973 ɛy J> % ̂ A... Communication System Dr. John J. Komo Distribui-.ion limited to ll—5—r" ■ ■ this report documents test f^T™^^^^^ limitation applied^eX m’ŕ^^ dist...FREQUENCY-SHIFT-KEYED COMMUNICATION SYSTEM . 3 III CYCLIC CODES .... 11 IV RANDOM ERROR-CORRECTING CODES V BURST ERROR-CORRECTING CODES

  1. Can intermediate-frequency magnetic fields affect memory function-related gene expressions in hippocampus of C57BL/6J mice?

    PubMed

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

    2013-01-01

    Recently, a cooking appliance based on the principle of electromagnetic induction has come to be used domestically on a widespread basis; this induction heating cooking hob mainly generates intermediate-frequency magnetic fields (IF-MF). However, whether electromagnetic fields originating from household appliances represent a health risk remains uncertain. We investigated the effect of IF-MF on the expressions of memory function-related genes and related transduction molecules in the mouse hippocampus. Male and female C57BL/6J mice were allotted to a control (sham-exposed), an exposure, or a recovery (one week after exposure) group and were exposed to IF-MF (21 kHz, 3.8 mT) one hour per day for 2 weeks. Twenty-four hour after final exposure, the expression levels of memory function-related genes and the mRNA levels for signal transduction pathway molecules in the hippocampi were examined using real-time RT-PCR. The relative mRNA expression levels of the N-methyl-D aspartate (NMDA) receptor subunits NR1, NR2A, and NR2B as well as transcription factors (calcium/calmodulin-dependent protein kinase (CaMK) -IV, cyclic AMP responsive element binding protein (CREB) -1) and neurotrophins (nerve growth factor (NGF), and brain-derived neurotrophic factors (BDNF)) were not significantly altered in the IF-MF-exposed mice. We also examined the morphology of the hippocampus using a histological analysis, but no changes in the IF-MF-exposed mice were seen. This is the first in vivo study to show that IF-MF exposure did not affect the expression levels of memory function-related genes in the hippocampus of C57BL/6J mice. The present findings suggest that IF-MF exposure may not affect cognitive function in the present animal model.

  2. Load Frequency Control of AC Microgrid Interconnected Thermal Power System

    NASA Astrophysics Data System (ADS)

    Lal, Deepak Kumar; Barisal, Ajit Kumar

    2017-08-01

    In this paper, a microgrid (MG) power generation system is interconnected with a single area reheat thermal power system for load frequency control study. A new meta-heuristic optimization algorithm i.e. Moth-Flame Optimization (MFO) algorithm is applied to evaluate optimal gains of the fuzzy based proportional, integral and derivative (PID) controllers. The system dynamic performance is studied by comparing the results with MFO optimized classical PI/PID controllers. Also the system performance is investigated with fuzzy PID controller optimized by recently developed grey wolf optimizer (GWO) algorithm, which has proven its superiority over other previously developed algorithm in many interconnected power systems.

  3. 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.

  4. Modal sensitivity for structural systems with repeated frequencies

    NASA Technical Reports Server (NTRS)

    Ojalvo, I. U.

    1987-01-01

    Repeated or closely packed modal frequencies are common physical occurrences for vibrating structures which are complex or possess multi-planes of symmetry. The computation of the sensitivity to structural modifications for these frequencies and mode shapes is made difficult by the fact that the mode shapes are not unique, since any linear combination of eigenvectors corresponding to a repeated eigenvalue is also an eigenvector. The work of Chen and Pan is extended, who used modal expansion techniques for accommodating the sensitivity analysis of structures with repeated eigenvalues. Starting with a discussion of the physical significance of sensitivity analysis for repeated frequency modes, a derivation is presented of the governing equations for the derivatives of a repeated eigenvalue. This is followed with a small example to illustrate the results. An efficient computation procedure, based upon an expansion of Nelson's ideas for large banded systems, is then proposed for systems with repeated or closely spaced eigenvalues.

  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. 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

  7. Planning-Programming-Budgeting System. Intermediate Unit Planning Study. Final Report.

    ERIC Educational Resources Information Center

    Montgomery County School Board, Norristown, PA.

    In 1965-66 most local school districts in Pennsylvania completed reorganization by consolidating 67 county school offices into 25 or 30 intermediate administrative units. This document presents the results of various task group activities and projected activities to develop a "generalized" educational planning, programing, budgeting…

  8. 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.

  9. 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.

  10. 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.

  11. The hagfish slime gland thread cell. I. A unique cellular system for the study of intermediate filaments and intermediate filament- microtubule interactions

    PubMed Central

    1984-01-01

    Thread cell differentiation in the slime gland of the Pacific hagfish Eptatretus stouti has been studied using light microscopy and scanning and transmission electron microscopy. Thread cell differentiation is remarkable in that the life history of the cell is largely dedicated to the production of a single, tapered, cylindrical, highly coiled, and precisely packaged cytoplasmic thread that may attain lengths of 60 cm and diameters approaching 1.5 micron. Each tapered thread, in turn, is comprised almost entirely of large numbers of intermediate filaments (IFs) bundled in parallel. During differentiation of the thread, the IFs become progressively more tightly packed. Various numbers of microtubules (MTs) are found among the bundled IFs during differentiation of the thread but disappear during the latter stages of thread differentiation. Observations of regularly spaced dots in longitudinal bisections of developing threads, diagonal striations in tangential sections of developing threads, and circumferentially oriented, filament-like structures observed at the periphery of developing threads cut in cross section have led us to postulate a helically oriented component(s) wrapped around the periphery of the developing thread. The enormous size of the fully differentiated thread cell, its apparent singular dedication to the production of IFs, the ease of isolating and purifying the threads and IF subunits (see accompanying paper), and the unique position of the hagfish in the phylogenetic scheme of vertebrate evolution all contribute to the attractiveness of the hagfish slime gland thread cell as a potential model system for studying IF subunit synthesis, IF formation from IF subunits, aggregation of IFs into IF bundles and the interaction(s) of IFs and MTs. PMID:6537952

  12. Universal distribution of component frequencies in biological and technological systems

    PubMed Central

    Pang, Tin Yau; Maslov, Sergei

    2013-01-01

    Bacterial genomes and large-scale computer software projects both consist of a large number of components (genes or software packages) connected via a network of mutual dependencies. Components can be easily added or removed from individual systems, and their use frequencies vary over many orders of magnitude. We study this frequency distribution in genomes of ∼500 bacterial species and in over 2 million Linux computers and find that in both cases it is described by the same scale-free power-law distribution with an additional peak near the tail of the distribution corresponding to nearly universal components. We argue that the existence of a power law distribution of frequencies of components is a general property of any modular system with a multilayered dependency network. We demonstrate that the frequency of a component is positively correlated with its dependency degree given by the total number of upstream components whose operation directly or indirectly depends on the selected component. The observed frequency/dependency degree distributions are reproduced in a simple mathematically tractable model introduced and analyzed in this study. PMID:23530195

  13. Frequency bands of strongly nonlinear homogeneous granular systems.

    PubMed

    Lydon, Joseph; Jayaprakash, K R; Ngo, Duc; Starosvetsky, Yuli; Vakakis, Alexander F; Daraio, Chiara

    2013-07-01

    Recent numerical studies on an infinite number of identical spherical beads in Hertzian contact showed the presence of frequency bands [Jayaprakash, Starosvetsky, Vakakis, Peeters, and Kerschen, Nonlinear Dyn. 63, 359 (2011)]. These bands, denoted here as propagation and attenuation bands (PBs and ABs), are typically present in linear or weakly nonlinear periodic media; however, their counterparts are not intuitive in essentially nonlinear periodic media where there is a complete lack of classical linear acoustics, i.e., in "sonic vacua." Here, we study the effects of PBs and ABs on the forced dynamics of ordered, uncompressed granular systems. Through numerical and experimental techniques, we find that the dynamics of these systems depends critically on the frequency and amplitude of the applied harmonic excitation. For fixed forcing amplitude, at lower frequencies, the oscillations are large in amplitude and governed by strongly nonlinear and nonsmooth dynamics, indicating PB behavior. At higher frequencies the dynamics is weakly nonlinear and smooth, in the form of compressed low-amplitude oscillations, indicating AB behavior. At the boundary between the PB and the AB large-amplitude oscillations due to resonance occur, giving rise to collisions between beads and chaotic dynamics; this renders the forced dynamics sensitive to initial and forcing conditions, and hence unpredictable. Finally, we study asymptotically the near field standing wave dynamics occurring for high frequencies, well inside the AB.

  14. Universal distribution of component frequencies in biological and technological systems.

    PubMed

    Pang, Tin Yau; Maslov, Sergei

    2013-04-09

    Bacterial genomes and large-scale computer software projects both consist of a large number of components (genes or software packages) connected via a network of mutual dependencies. Components can be easily added or removed from individual systems, and their use frequencies vary over many orders of magnitude. We study this frequency distribution in genomes of ∼500 bacterial species and in over 2 million Linux computers and find that in both cases it is described by the same scale-free power-law distribution with an additional peak near the tail of the distribution corresponding to nearly universal components. We argue that the existence of a power law distribution of frequencies of components is a general property of any modular system with a multilayered dependency network. We demonstrate that the frequency of a component is positively correlated with its dependency degree given by the total number of upstream components whose operation directly or indirectly depends on the selected component. The observed frequency/dependency degree distributions are reproduced in a simple mathematically tractable model introduced and analyzed in this study.

  15. 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.

  16. Load Frequency Control in Power System with Distributed Generation

    NASA Astrophysics Data System (ADS)

    Yukita, Kazuto; Ota, Takuya; Fujimoto, Koji; Goto, Yasuyuki; Ichiyanagi, Katuhiro

    This paper proposes a method to improve the load frequency control in a power system with distributed generation (DG). DG is assumed to include photovoltaic generation, wind power generation, fuel cells and etc. In this paper, a simulation is performed using a microgrid model or island model that is composed of a storage system with either wind power generation or photovoltaic generation system as the DG. The effectiveness of load frequency control (LFC) using a storage system is examined using a power transmission simulator. The model for the experiment has been composed of inverter, battery, synchronous generator and load. Using this model, the comparison examination was done in respect of output setting control and the case in which the PI control was used. As a result, when the output set-point control using power demand estimation method is executed, the control characteristic is very excellent.

  17. Tissue Viscoelasticity Measurement System by Simultaneous Multiple-Frequency Excitation

    NASA Astrophysics Data System (ADS)

    Miwa, Takashi; Yoshihara, Yuki; Kanzawa, Kouki; Parajuli, Raj Kumar; Yamakoshi, Yoshiki

    2012-07-01

    Tissue elasticity measurements by an ultrasonic wave are a promising technique for the qualitative diagnosis of tumors and liver diseases. The viscoelastic characteristics in soft tissue can be quantitatively evaluated by considering the frequency dependence of the velocity of the shear wave propagating in the tissue. To improve the reliability of the in vivo viscoelasticity measurement, we propose a novel elasticity imaging method using continuous vibration wave excitation, which was realized by developing a three dimensional ultrasonic (3D US) wave Doppler measurement system with multiple-frequency excitation. In vivo experiments on the brachial muscle were carried out in order to demonstrate the validity and effectiveness of the developed system. The experimental results show that this system can successfully measure the velocity of a shear wave propagating through a muscle layer. This system has the potential to obtain viscoelastic information from a target with high repeatability and reliability.

  18. Vibrational resonances in biological systems at microwave frequencies.

    PubMed Central

    Adair, Robert K

    2002-01-01

    Many biological systems can be expected to exhibit resonance behavior involving the mechanical vibration of system elements. The natural frequencies of such resonances will, generally, be in the microwave frequency range. Some of these systems will be coupled to the electromagnetic field by the charge distributions they carry, thus admitting the possibility that microwave exposures may generate physiological effects in man and other species. However, such microwave excitable resonances are expected to be strongly damped by interaction with their aqueous biological environment. Although those dissipation mechanisms have been studied, the limitations on energy transfers that follow from the limited coupling of these resonances to the electromagnetic field have not generally been considered. We show that this coupling must generally be very small and thus the absorbed energy is so strongly limited that such resonances cannot affect biology significantly even if the systems are much less strongly damped than expected from basic dissipation models. PMID:11867434

  19. 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)

    2016-01-01

    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.

  20. 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.

  1. 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)

    2017-01-01

    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.

  2. 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.

  3. Millennial total sea-level commitments projected with the Earth system model of intermediate complexity LOVECLIM

    NASA Astrophysics Data System (ADS)

    Goelzer, H.; Huybrechts, P.; Raper, S. C. B.; Loutre, M.-F.; Goosse, H.; Fichefet, T.

    2012-12-01

    Sea-level is expected to rise for a long time to come, even after stabilization of human-induced climatic warming. Here we use simulations with the Earth system model of intermediate complexity LOVECLIM to project sea-level changes over the third millennium forced with atmospheric greenhouse gas concentrations that stabilize by either 2000 or 2100 AD. The model includes 3D thermomechanical models of the Greenland and Antarctic ice sheets coupled to an atmosphere and an ocean model, a global glacier melt algorithm to account for the response of mountain glaciers and ice caps, and a procedure for assessing oceanic thermal expansion from oceanic heat uptake. Four climate change scenarios are considered to determine sea-level commitments. These assume a 21st century increase in greenhouse gases according to SRES scenarios B1, A1B and A2 with a stabilization of the atmospheric composition after the year 2100. One additional scenario assumes 1000 years of constant atmospheric composition from the year 2000 onwards. For our preferred model version, we find an already committed total sea-level rise of 1.1 m by 3000 AD. In experiments with greenhouse gas concentration stabilization at 2100 AD, the total sea-level rise ranges between 2.1 m (B1), 4.1 m (A1B) and 6.8 m (A2). In all scenarios, more than half of this amount arises from the Greenland ice sheet, thermal expansion is the second largest contributor, and the contribution of glaciers and ice caps is small as it is limited by the available ice volume of maximally 25 cm of sea-level equivalent. Additionally, we analysed the sensitivity of the sea-level contributions from an ensemble of nine different model versions that cover a large range of climate sensitivity realized by model parameter variations of the atmosphere-ocean model. Selected temperature indices are found to be good predictors for sea-level contributions from the different components of land ice and oceanic thermal expansion after 1000 years.

  4. Frequency Selective Surface Based Bandpass Filter for THz Communication System

    NASA Astrophysics Data System (ADS)

    Das, Subrata; Reza, Khan Mamun; Habib, Md. Ahsan

    2012-11-01

    In this work, a band pass filter based on frequency selective surface (FSS) is presented. The resonance of the FSS is achieved by perforating slot type ring structure on an Aluminum layer. To ensure adequate mechanical strength, this structure is again supported by a dielectric layer. The physical dimensions of the FSS, i.e. ring radius, slot width, cell dimension and width of the layers all are responsible for the resonance behavior. In its electrical equivalent circuit, these dimensions act as inductor and capacitor. The center frequency of the designed filter is at 0.16 THz with a -3 dB bandwidth of 18 GHz. This filter can be utilized as a part of any THz communication system to achieve application specific frequency discrimination. The simulation has been carried by using commercial software-CST Microwave Studio. The performance of the fabricated FSS is evaluated by Microwave Vector Network Analyzer.

  5. 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

  6. 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.

  7. New Frequency Step-Tunable Ecrh System for Asdex Upgrade

    NASA Astrophysics Data System (ADS)

    Wagner, D.; Leuterer, F.; Manini, A.; Monaco, F.; Münich, M.; Ryter, F.; Schütz, H.; Zohm, H.; Franke, T.; Heidinger, R.; Thumm, M.; Kasparek, W.; Gantenbein, G.; Litvak, A. G.; Popov, L. G.; Nichiporenko, V. O.; Myasnikov, V. E.; Denisov, G. G.; Tai, E. M.; Solyanova, E. A.; Malygin, S. A.

    2006-02-01

    A new broadband ECRH (Electron Cyclotron Resonance Heating) system is currently under construction at the ASDEX Upgrade tokamak. This system will employ multi-frequency gyrotrons step-tunable in the range 105 140 GHz. In its final stage the system will consist of 4 gyrotrons with a total power of 4 MW and a pulse length of 10 s. It employs a fast steerable launcher for feedback controlled deposition that allows for poloidal steering of 10° within 100 ms. Transmission line elements, such as corrugated waveguides, polarizer mirrors and vacuum windows, are designed to cope for this frequency band.

  8. 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.

  9. 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.

  10. Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

    NASA Astrophysics Data System (ADS)

    Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

    2017-05-01

    KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

  11. Efficient system for wavenumber-frequency analysis of underwater structures

    NASA Astrophysics Data System (ADS)

    Boober, Walter H.; Morton, David; Gedney, Charles; Abbot, Philip

    1998-06-01

    A watertight housing was developed to a low a scanning laser vibrometer (SLV) system to work underwater. Compared to other underwater optical measurement systems, this system offers distinct advantages, including ease of adaptation to a variety of teste, no requirement to be near tank windows, and a simplified rigging system. The system was recently sued to successfully conduct a wavenumber frequency evaluation of the vibratory response of a submerged cylindrical shell. The technical issues in developing the housing and assuring the integrity of the SLV accuracy during transition to underwater use will be discussed. Also, problems encountered in maximizing return signal strength, preparation of the shell, and the process of on-sight data transfer for quick-look wavenumber-frequency analysis while data are being acquired will be presented. The cylindrical shell was excited with 100 to 5000 Hz chirp signals by a 44 N shaker that was attached axially at the center of a bulkhead. A scan consisted of 3 columns with 64 measurement points per column. The shell was rotated 11.25 degrees and the scan repeated to collect an array of 32 by 64 equally spaced points totalling 6144 measurements. The time of data acquisition was about 11 hours. This underwater housing permitted the type of measurements that are not readily available with other systems. With most other techniques the collection time would have been significantly longer. The transfer functions between the velocities measured at each scan location and the shaker force signal were computed as functions of frequency. The transfer functions computed for the center scan columns were then transformed into the wavevector domain using a 2D FFT program. Preliminary results show that the shell response is concentrated near zero circumferential wavenumber, due to the axial symmetry of the driving force. Further, the maximum shell response is also concentrated near the ring frequency of the cylinder, at an axial wavenumber of

  12. A Performance Measurement System for the Aircraft Intermediate Maintenance Department Officer

    DTIC Science & Technology

    1976-06-01

    Air Station or ship and performs intermediate level maintenance on aircraft remuovable V components such as engines, avionic ec•uipment, ejection...seats, etc. In resource management terminolcgy, a shore-based AIMD is Al a cost center of a Naval Air Station which is designated as a responsibility...parent Naval Air Station . Thus, the purpose of the management control process is to accomplish the stated organizational objectives, effectively and

  13. 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

  14. Wind Generation Participation in Power System Frequency Response: Preprint

    SciTech Connect

    Gevorgian, Vahan; Zhang, Yingchen

    2017-01-01

    The electrical frequency of an interconnected power system must be maintained close its nominal level at all times. Excessive under- and overfrequency excursions can lead to load shedding, instability, machine damage, and even blackouts. There is a rising concern in the electric power industry in recent years about the declining amount of inertia and primary frequency response (PFR) in many interconnections. This decline may continue due to increasing penetrations of inverter-coupled generation and the planned retirements of conventional thermal plants. Inverter-coupled variable wind generation is capable of contributing to PFR and inertia with a response that is different from that of conventional generation. It is not yet entirely understood how such a response will affect the system at different wind power penetration levels. The modeling work presented in this paper evaluates the impact of wind generation's provision of these active power control strategies on a large, synchronous interconnection. All simulations were conducted on the U.S. Western Interconnection with different levels of instantaneous wind power penetrations (up to 80%). The ability of wind power plants to provide PFR - and a combination of synthetic inertial response and PFR - significantly improved the frequency response performance of the system.

  15. Primary central nervous system B cell lymphoma with features intermediate between diffuse large B cell lymphoma and Burkitt lymphoma

    PubMed Central

    Jiang, Liuyan; Li, Zhimin; Finn, Laura E; Personnet, David A; Edenfield, Brandy; Foran, James M; Jaeckle, Kurt A; Reimer, Ronald; Menke, David M; Ketterling, Rhett P; Tun, Han W

    2012-01-01

    B cell lymphoma with features intermediate between diffuse large B cell lymphoma and Burkitt lymphoma (DLBCL/BL) is a new lymphoma entity which is recognized in the current World Health Organization (WHO) classification (2008). We report a case of a primary central nervous system lymphoma (PCNSL) with findings consistent with DLBCL/BL. It is characterized by a very aggressive clinical course, and a widespread multifocal involvement of the CNS. Our case shows that a DLBCL/BL can manifest in the CNS alone without any systemic involvement. PMID:22295149

  16. Primary central nervous system B cell lymphoma with features intermediate between diffuse large B cell lymphoma and Burkitt lymphoma.

    PubMed

    Jiang, Liuyan; Li, Zhimin; Finn, Laura E; Personnet, David A; Edenfield, Brandy; Foran, James M; Jaeckle, Kurt A; Reimer, Ronald; Menke, David M; Ketterling, Rhett P; Tun, Han W

    2012-01-01

    B cell lymphoma with features intermediate between diffuse large B cell lymphoma and Burkitt lymphoma (DLBCL/BL) is a new lymphoma entity which is recognized in the current World Health Organization (WHO) classification (2008). We report a case of a primary central nervous system lymphoma (PCNSL) with findings consistent with DLBCL/BL. It is characterized by a very aggressive clinical course, and a widespread multifocal involvement of the CNS. Our case shows that a DLBCL/BL can manifest in the CNS alone without any systemic involvement.

  17. 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.

  18. Analytical estimates of secular frequencies for binary star systems

    NASA Astrophysics Data System (ADS)

    Bazsó, Á.; Pilat-Lohinger, E.

    2017-03-01

    Binary and multiple star systems are extreme environments for the formation and long-term presence of extrasolar planets. Circumstellar planets are subject to gravitational perturbations from the distant companion star, and this interaction leads to a long-period precession of their orbits. We investigate analytical models that allow to quantify these perturbations and calculate the secular precession frequency in the dynamical model of the restricted three-body problem. These models are applied to test cases and we discuss some of their shortcomings. In addition, we introduce a modified Laplace-Lagrange model which allows to obtain better frequency estimates than the traditional model for large eccentricities of the perturber. We then generalize this model to any number of perturbers, and present an application to the four-body problem.

  19. 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.

  20. 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.

  1. A robust decentralized load frequency controller for interconnected power systems.

    PubMed

    Dong, Lili; Zhang, Yao; Gao, Zhiqiang

    2012-05-01

    A novel design of a robust decentralized load frequency control (LFC) algorithm is proposed for an inter-connected three-area power system, for the purpose of regulating area control error (ACE) in the presence of system uncertainties and external disturbances. The design is based on the concept of active disturbance rejection control (ADRC). Estimating and mitigating the total effect of various uncertainties in real time, ADRC is particularly effective against a wide range of parameter variations, model uncertainties, and large disturbances. Furthermore, with only two tuning parameters, the controller provides a simple and easy-to-use solution to complex engineering problems in practice. Here, an ADRC-based LFC solution is developed for systems with turbines of various types, such as non-reheat, reheat, and hydraulic. The simulation results verified the effectiveness of the ADRC, in comparison with an existing PI-type controller tuned via genetic algorithm linear matrix inequalities (GALMIs). The comparison results show the superiority of the proposed solution. Moreover, the stability and robustness of the closed-loop system is studied using frequency-domain analysis.

  2. Imaging capability of the higher-frequency subsystem of a dual-frequency acoustic lens sonar system

    NASA Astrophysics Data System (ADS)

    Lopes, Joseph L.; Paustian, Iris C.; Marciniak, Robert; Van Tol, Dave; Folds, Donald L.

    2000-07-01

    An experimental dual-frequency acoustic lens sonar system, designed to detect both buried and non-buried objects is described with emphasis on the higher frequency subsystem. The lower frequency subsystem (35 - 100 kHz) forms conical beams with beam widths near 5 degree(s) using discrete transducer elements in the lens focal plane for both transmission and reception. The higher frequency (1 - 2 MHz) lens system is designed to be contained within the volume of the lower frequency subsystem to create a compact dual-frequency system. The higher frequency system consists of three 20-cm long cylindrical lenses designed to form fan-shaped beams over a 20 degree(s) field of view. The retina is positioned 34 cm from the entrance aperture. A test array containing several discrete elements with 1.0-mm pitch has been designed for initial testing. The final system will use a retina with 80 - 100 elements. The imaging system is designed to generate images with cross-range resolutions from 0.1 degree(s) to 0.25 degree(s), and is designed to be tested in both bistatic or monostatic modes. In the monostatic mode, results of spatial multiplexing of beams in the ratio of 3, 4, and 5 will be compared. The system is designed to make a thorough parametric evaluation of imaging in the 1 - 2 MHz range over a wide range of angular resolutions and to relate design parameters to operational performance for forward looking systems.

  3. Frequency dependent and transient characteristics of substation grounding systems

    SciTech Connect

    Grcev, L.D. Heimbach, M.

    1997-01-01

    In spite of the existence of a number of analytical models aimed for transient analysis of large grounding systems, more detailed analysis of the influence of different parameters on the transient performance of large ground grids subjected to lightning current impulse is not available. This paper presents analysis of the influence of soil conductivity, location of feed point, grid size, depth, conductor separation, ground rods, and shape of the lightning current impulse, on the transient performance of ground grids with sizes ranging from 10 x 10 m{sup 2} to 120 x 120 m{sup 2} and with 4 to 124 meshes. Maximal transient ground potential rise and frequency dependent impedance are analyzed in time and frequency domain, respectively. Computations are made with computer model based on the electromagnetic field theory approach, taking accurately into account frequency dependent characteristics of large ground grids. Instead of usual simple approximations of the lightning current impulse, recorded channel base currents from triggered lightning are used for the time domain analysis.

  4. 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.

  5. Analysis of secured Optical Orthogonal Frequency Division Multiplexed System

    NASA Astrophysics Data System (ADS)

    Gill, Harsimranjit Singh; Bhatia, Kamaljit Singh; Gill, Sandeep Singh

    2017-05-01

    In this paper, security issues for optical orthogonal frequency division multiplexed (OFDM) systems are emphasized. The encryption has been done on the data of coded OFDM symbols using data encryption standard (DES) algorithm before transmitting through the fiber. The results obtained justify that the DES provides better security to the input data without further bandwidth requirement. The data is transmitted to a distance of 1,000 km in a single-mode fiber with 16-quadrature amplitude modulation. The peak-to-average power ratio and optical signal-to-noise ratio of secure coded OFDM signal is fairly better than the conventional OFDM signal.

  6. 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.

  7. 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.

  8. Controlled radio frequency vessel sealing system for surgical applications

    NASA Astrophysics Data System (ADS)

    Kennedy, Jenifer S.; Buysse, Steve; Chandler, James; Eggleston, Jeff; Taylor, Kenneth D.; Thomsen, Sharon L.

    1998-04-01

    A radio frequency tissue welding system has been developed for occlusion of vessels during surgery. The system is designed to replace commonly used mechanical clip and suture ligation techniques. Other energy based ligation techniques are limited to use on small structures (system consists of forceps and an RF electrosurgery generator, both of which are specifically designed for optimal tissue sealing. The method combines optimal pressure delivery to the tissue and energy delivery consisting of a high heat cycle, a low heat cycle and a cooling cycle. The generator output is also voltage limited and delivers high current in order to remodel the collagen in approximately 5 seconds with no sticking or charring. The vessel sealing system was compared to other energy based ligation techniques including ultrasonic sealing and other bipolar systems. The pressure required to burst the vessel was used for comparison. Average burst pressures on 3 - 7 mm arteries were 126 +/- 154 mmHg, 607 +/- 314 mmHg, and 913 +/- 304 mmHg for ultrasonic, standard bipolar, and vessel sealing, respectively. Histologic evaluation showed vessel wall fusion and minimal thermal damage to adjacent tissues for the vessel sealing system.

  9. 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.

  10. System identification and controller design using experimental frequency response data

    NASA Technical Reports Server (NTRS)

    Irwin, R. Dennis

    1990-01-01

    Recent findings from modeling and controller design for the NASA-Marshall Single Structure Control Facility have raised questions regarding the ability of modern control design techniques and modern modeling techniques to deal effectively with the stringent modeling and control design requirements of Large Space Structure Control. A brief and general discussion is presented of the results of studies into the modeling and control issues performed under sponsorship of the NASA/ASEE Summer Faculty Fellowship Program. Several issues are addressed. The first is a study of a modeling technique based on least squares identification of individual transfer functions from measured frequency response data. The second is a study of multiobjective optimization techniques applied to the modeling, or system identification, problem. The third issue is a study into the question of whether multiobjective optimization approaches can be effectively used for control system design using only frequency response data, thereby bypassing the difficult modeling problem. The last issue studied involves the resolution of seeming discrepancies between predicted and measured control computer time delays in the Single Structure Control Facility.

  11. 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.

  12. 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.

  13. A versatile power converter for high-frequency link systems

    NASA Technical Reports Server (NTRS)

    Sood, Pradeep K.; Lipo, Thomas A.; Hansen, Irving G.

    1988-01-01

    A single-phase HF link appears to be an attractive alternative to the dc link commonly used in power conversion systems. Here, a power converter suitable for one-step conversion of the single-phase HF link voltage to the three-phase LF voltages typically required for interfacing with system sources and loads is proposed. The converter utilizes zero-voltage switching principles to minimize switching losses and an easy-to-implement technique of pulse-density modulation for the control of the amplitude, frequency, and waveshape of the synthesized LF signals. Adaptation of the proposed topology for power conversion to single-phase ac and dc voltage or current outputs is shown to be straightforward. The feasibility of the proposed power circuit and the control technique has been experimentally verified.

  14. Discrete pulse modulation strategies for high-frequency inverter systems

    NASA Astrophysics Data System (ADS)

    Venkataramanan, Giri; Divan, Deepakraj M.; Jahns, Thomas M.

    1993-07-01

    High-performance, high-frequency inverter systems for UPS (uninterruptible power system) applications cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant dc link inverter require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. A controller that utilizes a load current feedforward strategy with a cost function current regulator to achieve excellent transient performance characteristics is presented. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this work focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well.

  15. 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)

  16. Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

    NASA Astrophysics Data System (ADS)

    Wang, Xiufang; Nie, Xinyi; Liang, Yilang; Lu, Falong; Yan, Zhongming; Wang, Yu

    2017-01-01

    Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

  17. Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems.

    PubMed

    Hou, Li; Xie, Jianchun; Zhao, Jian; Zhao, Mengyao; Fan, Mengdie; Xiao, Qunfei; Liang, Jingjing; Chen, Feng

    2017-10-01

    To explore initial Maillard reaction pathways and mechanisms for maximal formation of meaty flavors in heated cysteine-xylose-glycine systems, model reactions with synthesized initial Maillard intermediates, Gly-Amadori, TTCA (2-threityl-thiazolidine-4-carboxylic acids) and Cys-Amadori, were investigated. Relative relativities were characterized by spectrophotometrically monitoring the development of colorless degradation intermediates and browning reaction products. Aroma compounds formed were determined by solid-phase microextraction combined with GC-MS and GC-olfactometry. Gly-Amadori showed the fastest reaction followed by Cys-Amadori then TTCA. Free glycine accelerated reaction of TTCA, whereas cysteine inhibited that of Gly-Amadori due to association forming relatively stable thiazolidines. Cys-Amadori/Gly had the highest reactivity in development of both meaty flavors and brown products. TTCA/Gly favored yielding meaty flavors, whereas Gly-Amadori/Cys favored generation of brown products. Conclusively, initial formation of TTCA and pathway involving TTCA with glycine were more applicable to efficiently produce processed-meat flavorings in a cysteine-xylose-glycine system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. 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.

  19. Preliminary Results From the UNICIT High Frequency Microwave Palaeointensity System

    NASA Astrophysics Data System (ADS)

    Biggin, A.; Boehnel, H.; Walton, D.

    2002-05-01

    Two of the biggest problems encountered when using the Thellier method to obtain estimates of the geomagnetic field intensity in the past are thermochemical alteration occurring during the experiments and the time intensive nature of the experiments themselves. Together these factors frequently yield a frustratingly low ratio of success achieved to time spent in the laboratory. However this ratio can be much increased, if microwave radiation instead of conventional thermal energy is used to excite the ferromagnetic grains within samples. Following the recent success of the geomagnetism group at the University of Liverpool in using microwave radiation to perform palaeointensity experiments, a new system has been developed at the Earth science research unit (UNICIT) of UNAM in Querétaro, Mexico. Conceptually, it differs from the Liverpool system (described in the literature) only in that it is designed to use higher frequency microwave radiation (12 to 18 GHz as opposed to 8.5 GHz) as a more efficient means to excite the ferromagnetic systems of materials. The system has been used to perform modified Thellier palaeointensity experiments on volcanic samples which had previously had a full TRM imparted to them using a known field in the laboratory. The results of these experiments were very encouraging and will be presented. Currently, samples derived from recent volcanic material which has previously undergone conventional Thellier analysis are being studied using the microwave system. Results from these experiments will also be discussed.

  20. 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.

  1. 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

  2. A hybrid single-end-access MZI and Φ-OTDR vibration sensing system with high frequency response

    NASA Astrophysics Data System (ADS)

    Zhang, Yixin; Xia, Lan; Cao, Chunqi; Sun, Zhenhong; Li, Yanting; Zhang, Xuping

    2017-01-01

    A hybrid single-end-access Mach-Zehnder interferometer (MZI) and phase sensitive OTDR (Φ-OTDR) vibration sensing system is proposed and demonstrated experimentally. In our system, the narrow optical pulses and the continuous wave are injected into the fiber through the front end of the fiber at the same time. And at the rear end of the fiber, a frequency-shift-mirror (FSM) is designed to back propagate the continuous wave modulated by the external vibration. Thus the Rayleigh backscattering signals (RBS) and the back propagated continuous wave interfere with the reference light at the same end of the sensing fiber and a single-end-access configuration is achieved. The RBS can be successfully separated from the interference signal (IS) through digital signal process due to their different intermediate frequency based on frequency division multiplexing technique. There is no influence between these two schemes. The experimental results show 10 m spatial resolution and up to 1.2 MHz frequency response along a 6.35 km long fiber. This newly designed single-end-access setup can achieve vibration events locating and high frequency events response, which can be widely used in health monitoring for civil infrastructures and transportation.

  3. 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)

  4. SPINS: a laboratory information management system for organizing and archiving intermediate and final results from NMR protein structure determinations.

    PubMed

    Baran, Michael C; Moseley, Hunter N B; Aramini, James M; Bayro, Marvin J; Monleon, Daniel; Locke, Jessica Y; Montelione, Gaetano T

    2006-03-01

    Recent technological advances and experimental techniques have contributed to an increasing number and size of NMR datasets. In order to scale up productivity, laboratory information management systems for handling these extensive data need to be designed and implemented. The SPINS (Standardized ProteIn Nmr Storage) Laboratory Information Management System (LIMS) addresses these needs by providing an interface for archival of complete protein NMR structure determinations, together with functionality for depositing these data to the public BioMagResBank (BMRB). The software tracks intermediate files during each step of an NMR structure-determination process, including: data collection, data processing, resonance assignments, resonance assignment validation, structure calculation, and structure validation. The underlying SPINS data dictionary allows for the integration of various third party NMR data processing and analysis software, enabling users to launch programs they are accustomed to using for each step of the structure determination process directly out of the SPINS user interface.

  5. Low-frequency oscillation in a narrow vibrated granular system

    NASA Astrophysics Data System (ADS)

    Oyarte Gálvez, Loreto; van der Meer, Devaraj

    2015-11-01

    The analogy of the behaviour of granular materials with that of fluids has motivated much appealing research. An important example is a vertically shaken granular bed which exhibits fluid-like behavior, such as the Leidenfrost effect where a dense layer of grains floats on top of a gaseous layer, just like when a liquid droplet floats on its own vapour above a hot plate. When the shaking energy is increased the granular bed transits from the Leidenfrost to the convection state, for which a precursor is expected in the form of an oscillation of the bed as a whole. This precursor was observed numerically like an oscillation in the motion of the dense part, where the frequency of this oscillation is much lower than the frequency of the injected energy, and appears more relevant when the system is getting closer to the convective state. We built a setup that permits the observation of the granular Leidenfrost effect for a wide range of driving parameters. More specifically, a monodisperse granular material is contained in a transparent box and vertically shaken, and a fast camera is used to study its dynamics. The presence of a LFO is directly measured by images analysis and shows a good agreement with the previous numerical and experimental works.

  6. Frequency-agile THz-wave generation and detection system using nonlinear frequency conversion at room temperature.

    PubMed

    Guo, Ruixiang; Ikar'i, Tomofumi; Zhang, Jun; Minamide, Hiroaki; Ito, Hiromasa

    2010-08-02

    A surface-emitting THz parametric oscillator is set up to generate a narrow-linewidth, nanosecond pulsed THz-wave radiation. The THz-wave radiation is coherently detected using the frequency up-conversion in MgO: LiNbO(3) crystal. Fast frequency tuning and automatic achromatic THz-wave detection are achieved through a special optical design, including a variable-angle mirror and 1:1 telescope devices in the pump and THz-wave beams. We demonstrate a frequency-agile THz-wave parametric generation and THz-wave coherent detection system. This system can be used as a frequency-domain THz-wave spectrometer operated at room-temperature, and there are a high possible to develop into a real-time two-dimensional THz spectral imaging system.

  7. Molecular orbital studies of enzyme activity: I: Charge relay system and tetrahedral intermediate in acylation of serine proteinases.

    PubMed Central

    Scheiner, S; Kleier, D A; Lipscomb, W N

    1975-01-01

    The charge relay ststem and its role in the acylation of serine proteinases is studied using the partial retention of diatomic differential overlap (PRDDO) technique to perform approximate ab initio molecular orbital calculations on a model of the enzyme-substrate complex. The aspartate in the charge relay system is seen to act as the ultimate proton acceptor during the charging of the serine nucleophile. A projection of the potential energy surface is obtained in a subspace corresponding to this charge transfer and to the coupled motions of active site residues and the substrate. These results together with extended basis set results for cruder models suggest that a concerted transfer of protons from Ser-195 to His-57 and from His-57 to Asp-102 occurs with an energy barrier of 20-25 kcal/mole (84-105 kJ/mole). The subsequent nucleophilic attack on the scissile peptide linkage by the charged serine is then seen to proceed energetically downhill to the tetrahedral intermediate. The formation of the tetrahedral intermediate from the Michaelis complex is calculated to be nearly thermoneutral. PMID:1058476

  8. Electrochemical system and method for electropolishing superconductive radio frequency cavities

    DOEpatents

    Taylor, E. Jennings; Inman, Maria E.; Hall, Timothy

    2015-04-14

    An electrochemical finishing system for super conducting radio frequency (SCRF) cavities including a low viscosity electrolyte solution that is free of hydrofluoric acid, an electrode in contact with the electrolyte solution, the SCRF cavity being spaced apart from the electrode and in contact with the electrolyte solution and a power source including a first electrical lead electrically coupled to the electrode and a second electrical lead electrically coupled to the cavity, the power source being configured to pass an electric current between the electrode and the workpiece, wherein the electric current includes anodic pulses and cathodic pulses, and wherein the cathodic pulses are interposed between at least some of the anodic pulses. The SCRF cavity may be vertically oriented during the finishing process.

  9. Discrete pulse modulation strategies for high-frequency inverter systems

    SciTech Connect

    Venkataramanan, G. . Dept. of Electrical Engineering); Divan, D.M. . Dept. of Electrical and Computer Engineering); Jahns, T.M. )

    1993-07-01

    High-performance high-frequency inverter systems for UPS applications represent a demanding application that cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant dc link inverter require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. This paper presents a controller that utilizes load current feed-forward strategy with a cost function current regulator to achieve excellent transient performance characteristics. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this paper focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well.

  10. 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.

  11. High Frequency Monitoring System of Groundwater Level in Sheliao

    NASA Astrophysics Data System (ADS)

    Lee, C.; Chia, Y.; Chuang, P.

    2012-12-01

    Long-term groundwater monitoring had been executed since 1950s in Taiwan. In 1980s, with improving technology, various types of automatic reorders of groundwater level had become the most widely used equipment in groundwater monitoring. Among these devices, submersible pressure transducer is frequently selected to monitor groundwater level for its high frequency and high resolution. In this study, it is chosen to monitor groundwater level change in Sheliao well. On the other hand, factors which might influence the performance of recorded data were excluded in the early stage of establishment as well. And the final approach is to achieve a comprehensive understanding of the minor groundwater level change of Sheliao well, and specify its connection between precipitation, atmosphere, earth tide and earthquake. The Shelia well is located in central Taiwan, constructed in an unconfined aquifer, recorded hourly groundwater level change since 1997. We tried to establish a 1 Hz sampling rate pressure-sensing system in 2011 June. The groundwater level was monitored in a resolution of 2-mm. According to the records, several small-scale of fluctuations were observed and were all correlate well to the earthquakes. However, during the time that no earthquake occurred, some short-term fluctuations were still occurred, performed in a different pattern to those induced by earthquakes. After further investigation, those anomalous fluctuations of groundwater level were found corresponded to precipitation quite well. The fluctuations were observed under some specific condition, which involving different range of accumulated precipitation, rainfall intensity, and rainfall duration. The result implied groundwater level in Sheliao well changes with loading effect result from runoff on the ground surface and infiltration. And the earth tide lead to regularly change was also observed. We conclude that Sheliao can be characterized as a partial-confined aquifer with high frequency and high

  12. The NASA data systems standardization program - Radio frequency and modulation

    NASA Astrophysics Data System (ADS)

    Martin, W. L.

    The modifications being considered by the NASA-ESA Working Group (NEWG) for space-data-systems standardization to maximize the commonality of the NASA and ESA RF and modulation systems linking spaceborne scientific experiments with ground stations are summarized. The first phase of the NEWG project shows that the NASA MK-IVA Deep Space Network and Shuttle Interrogator (SI) systems in place or planned for 1985 are generally compatible with the ESA Network, but that communications involving the Tracking and Data Relay Satellite (TDRS) are incompatible due to its use of spread-spectrum modulation, pseudonoise ranging, multiple-access channels, and Mbit/s data rates. Topics under study for the post-1985 period include low-bit-rate capability for the ESA Network, an optional 8-kHz command subcarrier for the SI, fixing the spacecraft-transponder frequency-multiplication ratios for possible X-band uplinks or X-band nondeep-space downlinks, review of incompatible TDRS features, and development of the 32-GHz band.

  13. The NASA data systems standardization program - Radio frequency and modulation

    NASA Technical Reports Server (NTRS)

    Martin, W. L.

    1983-01-01

    The modifications being considered by the NASA-ESA Working Group (NEWG) for space-data-systems standardization to maximize the commonality of the NASA and ESA RF and modulation systems linking spaceborne scientific experiments with ground stations are summarized. The first phase of the NEWG project shows that the NASA MK-IVA Deep Space Network and Shuttle Interrogator (SI) systems in place or planned for 1985 are generally compatible with the ESA Network, but that communications involving the Tracking and Data Relay Satellite (TDRS) are incompatible due to its use of spread-spectrum modulation, pseudonoise ranging, multiple-access channels, and Mbit/s data rates. Topics under study for the post-1985 period include low-bit-rate capability for the ESA Network, an optional 8-kHz command subcarrier for the SI, fixing the spacecraft-transponder frequency-multiplication ratios for possible X-band uplinks or X-band nondeep-space downlinks, review of incompatible TDRS features, and development of the 32-GHz band.

  14. Intermediate photovoltaic system application experiment operational performance report. Volume 4: Beverly High School, Beverly, Mass.

    NASA Astrophysics Data System (ADS)

    1982-01-01

    Performance data are presented for the months of November and December, 1981 for a photovoltaic power supply at a Massachusetts school building. The ata include: monthly and daily electrical energy produced; monthly and daily solar energy received; monthly and daily array efficiency; energy produced as a function of power level, voltage, cell temperature, and hour of the day; input, output, and efficiency of two power conditioner units and for the total power conditioning system; energy supplied by the photovoltaic system to the load during each day and month; photovoltaic system efficiency; capacity factor; daily system availability; monthly and hourly insolation; heating and cooling degree days; number of freeze-thaw cycles per month; monthly and hourly ambient temperature; monthly and hourly wind speed; wind direction distribution; hourly cell temperature; and data acquisition mode and recording interval plot.

  15. Intermediate photovoltaic system application experiment operational performance report. Volume 4, for Beverly High School, Beverly, MA

    SciTech Connect

    Not Available

    1982-01-01

    Performance data are presented for the months of November and December, 1981 for a photovoltaic power supply at a Massachusetts school building. The data include: monthly and daily electrical energy produced; monthly and daily solar energy received; monthly and daily array efficiency; energy produced as a function of power level, voltage, cell temperature, and hour of the day; input, output, and efficiency of two power conditioner units and for the total power conditioning system; energy supplied by the photovoltaic system to the load during each day and month; photovoltaic system efficiency; capacity factor; daily system availability; monthly and hourly insolation; heating and cooling degree days; number of freeze/thaw cycles per month; monthly and hourly ambient temperature; monthly and hourly wind speed; wind direction distribution; hourly cell temperature; and data acquisition mode and recording interval plot. (LEW)

  16. Coastal Storm Surge Analysis: Computational System, Report 2: Intermediate Submission No. 1.2

    DTIC Science & Technology

    2011-03-01

    Figure 2.15 Data sources utilized to define mesh bathymetry and topography. Nodes shaded in green utilized DEM elevations, those in magenta used the...complete end-to-end modeling system, with all required forcing inputs, for updating the floodplain levels for coastal and inland watershed communities ...Geographic Information System (GIS) tools to facilitate archiving, distribution, and analysis of the various storm surge data products Under the

  17. 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

  18. Precocious expression of NAPA-73, an intermediate filament-associated protein, during nervous system and heart development in the chicken embryo.

    PubMed

    Ciment, G

    1990-01-01

    A monoclonal antibody was generated, against early neural crest-derived cells, which recognizes an epitope present on a novel intermediate filament-associated protein. This protein has been named NAPA-73 and is expressed by progenitor cells of the nervous system and heart. Biochemical and ultrastructural studies indicate that this protein associates with bundles of intermediate filaments and therefore may play a role in the determination of cell shape.

  19. 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.

  20. Method of detecting system function by measuring frequency response

    DOEpatents

    Morrison, John L [Butte, MT; Morrison, William H [Manchester, CT; Christophersen, Jon P [Idaho Falls, ID

    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.

  1. 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.

  2. Intermediate photovoltaic system application experiment operational performance report. Volume 8: Newman Power Station, El Paso, Texas

    NASA Astrophysics Data System (ADS)

    1982-02-01

    For the month of January, 1982, performance data are given for a photovoltaic power supply used by a Texas electric utility. Data presented include: daily and monthly electrical energy produced; daily and monthly solar energy incident on the array; daily and monthly array efficiency; plots of energy produced as a function of power levels, voltage, cell temperature, and hour of day; electrical energy supplied by the photovoltaic system to the load and the corresponding dollar value; photovoltaic system efficiency; capacity factor; daily photovoltaic power supplied to the load; daily system availability; hourly and monthly insolation; hourly and monthly ambient temperature; hourly and monthly average wind speed; wind direction distribution; number of freeze/thaw cycles; heating and cooling degree days; hourly cell temperature; daily data acquisition mode and recording interval plot. Also included are brief summaries of problems, operations and maintenance events.

  3. An intermediate solution between basic and expanded aircraft integrated data systems (AIDS)

    NASA Astrophysics Data System (ADS)

    Robert, C.

    1981-11-01

    A single digital flight data acquisition and management unit, divided for reliability into two parts, is proposed as an alternative to ARINC 717. One part deals with mandatory parameters which are sampled, coded, and transmitted in a PCM stream to the digital flight data recorder. The second part processes the parameters and is user programmable. Analysis consists of exceedance processing (e.g., engine, nacelle) gas pass analysis, AIDS monitoring and aircraft system warning from the flight warning computer. Airline response indicates that this system meets their requirements.

  4. Intermediate photovoltaic system application experiment operational performance. Volume 6: Newman Power Station, El Paso, Texas

    NASA Astrophysics Data System (ADS)

    1982-01-01

    Performance data for the month of December 1981 for a 20 kW peak photovoltaic flat panel power system for an uninterruptable power supply load at an El Paso, Texas utility ae given. Data include monthly total and daily insolation, monthly total and daily electrical energy, and array efficiency. Also plotted are the data acquisition mode and recording intervals for each day of the month. Three site events (maintenance and system problems) are summarized, and missing data from December 25 through December 30 are explained.

  5. A Taylor series approach for coupled queueing systems with intermediate load

    NASA Astrophysics Data System (ADS)

    Evdokimova, Ekaterina; Wittevrongel, Sabine; Fiems, Dieter

    2017-07-01

    We focus on the numerical analysis of a coupled queueing system with Poisson arrivals and exponentially distributed service times. Such a system consists of multiple queues served by a single server. Service is synchronised meaning that there is a departure from every queue upon service completion and there is no service whenever one of the queues is empty. It was shown before that the terms in the Maclaurin series expansion of the steady-state distribution of this queueing system when the service rate is sent to 0 (overload) can be calculated efficiently. In the present paper we extend this approach to lower loads. We focus on a sequence of Taylor series expansions of the stationary distribution around increasing service rates. For each series expansion, we use Jacobi iteration to calculate the terms in the series expansion where the initial solution is the approximation found by the preceding series expansion. As the generator matrix of the queueing system at hand is sparse, the numerical complexity of a single Jacobi iteration is O(N MK), where N is the order of the series expansion, K is the number of queues and M is the size of the state space. Having a good initial solution reduces the number of Jacobi iterations considerably, meaning that we can find a sequence of good approximations of the steady state probabilities fast.

  6. Frequency response analysis of IPMC actuators by an IR system

    NASA Astrophysics Data System (ADS)

    Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore

    2005-05-01

    Ionic Polymer Metal Composites or IPMCs are emerging materials belonging to EAP class. They are of increasing interest in innovative applications due to several advantages respect to competing technologies (SMA, piezoelectric, etc.), such as the possibility to be used both as moving actuators and sensors, their lightness and the low actuation voltage. On the other hand their behaviour is not fully known and it is still subjected to deep investigations. In this perspective the development of a complete model, able to fully describe the electromechanical properties of the IPMC materials, is the aim of many research groups. To that purpose this work focuses on designing and realising a system to determine the frequency domain behaviour of an IPMC strip as actuator in order to collect information useful to model it. Here the IPMC deformation, caused by applying a voltage input signal across its thickness, is detected by using an infrared transmitter-receiver couple. This methodology is largely diffused and it is based on the acquisition of the intensity of the emitted ray after being reflected by the moving target, moreover it constitutes a low cost solution. Also a transducer is used to acquire information about the current absorbed by the device under test. For the specific application a conditioning circuitry and the software for signal processing has been designed and realised. Preliminary results show that the proposed system allows to infer a number of interesting properties of IPMC based actuators.

  7. Frequency distribution of coliforms in water distribution systems.

    PubMed Central

    Christian, R R; Pipes, W O

    1983-01-01

    Nine small water distribution systems were sampled intensively to determine the patterns of dispersion of coliforms. The frequency distributions of confirmed coliform counts were compatible with either the negative-binomial or the lognormal distribution. They were not compatible with either the Poisson or Poisson-plus-added zeroes distribution. The implications of the use of the lognormal distributional model were further evaluated because of its previous use in water quality studies. The geometric means from 14 data sets ranged from 10(-6) to 0.2 coliforms per 100 ml, and the geometric standard deviations were between 10 and 100, with one exception. If the lognormal model is representative of the coliform distribution; the arithmetic mean sample count is a poor estimator of the true mean coliform density, and the probability of water in a distribution system containing small patches with large coliform densities without detection by routine monitoring is finite. These conclusions have direct bearing on the interpretation of microbiological quality standards for drinking water. PMID:6830219

  8. On Frequencies of Small Oscillations of Some Dynamical Systems Associated with Root Systems

    NASA Astrophysics Data System (ADS)

    Perelomov, A. M.

    In the paper by F. Calogero and author [Commun. Math. Phys. 59 (1978) 109-116] the formula for frequencies of small oscillations of the Sutherland system ($A_l$ case) was found. In present note the generalization of this formula for the case of arbitrary root system is given.

  9. 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.

  10. The Dermatan Sulfate Proteoglycan Decorin Modulates α2β1 Integrin and the Vimentin Intermediate Filament System during Collagen Synthesis

    PubMed Central

    Jungmann, Oliver; Nikolovska, Katerina; Stock, Christian; Schulz, Jan-Niklas; Eckes, Beate; Riethmüller, Christoph; Owens, Rick T.; Iozzo, Renato V.; Seidler, Daniela G.

    2012-01-01

    Decorin, a small leucine-rich proteoglycan harboring a dermatan sulfate chain at its N-terminus, is involved in regulating matrix organization and cell signaling. Loss of the dermatan sulfate of decorin leads to an Ehlers-Danlos syndrome characterized by delayed wound healing. Decorin-null (Dcn−/−) mice display a phenotype similar to that of EDS patients. The fibrillar collagen phenotype of Dcn−/− mice could be rescued in vitro by decorin but not with decorin lacking the glycosaminoglycan chain. We utilized a 3D cell culture model to investigate the impact of the altered extracellular matrix on Dcn−/− fibroblasts. Using 2D gel electrophoresis followed by mass spectrometry, we identified vimentin as one of the proteins that was differentially upregulated by the presence of decorin. We discovered that a decorin-deficient matrix leads to abnormal nuclear morphology in the Dcn−/− fibroblasts. This phenotype could be rescued by the decorin proteoglycan but less efficiently by the decorin protein core. Decorin treatment led to a significant reduction of the α2β1 integrin at day 6 in Dcn−/− fibroblasts, whereas the protein core had no effect on β1. Interestingly, only the decorin core induced mRNA synthesis, phosphorylation and de novo synthesis of vimentin indicating that the proteoglycan decorin in the extracellular matrix stabilizes the vimentin intermediate filament system. We could support these results in vivo, because the dermis of wild-type mice have more vimentin and less β1 integrin compared to Dcn−/−. Furthermore, the α2β1 null fibroblasts also showed a reduced amount of vimentin compared to wild-type. These data show for the first time that decorin has an impact on the biology of α2β1 integrin and the vimentin intermediate filament system. Moreover, our findings provide a mechanistic explanation for the reported defects in wound healing associated with the Dcn−/− phenotype. PMID:23226541

  11. 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.

  12. Intermediate photovoltaic system application experiment operational performance report. Volume 3: Beverly High School, Beverly, Massachusetts

    NASA Astrophysics Data System (ADS)

    1981-12-01

    Software and hardware problems resulted in the loss of sixteen days of data during September. The total electrical energy produced by the PV system during September is listed as 3986 kWh. The meter is manually read only about every other month, but readings which bracket a majority of the days of the month of September indicate an average daily output of 220 kWh per day or 6600 kWh total for the month. Using the average inverter efficiency of 88 percent, shown in report Module 4, infers that the array produced 7500 kWh of dc output energy during September. Similar analysis for October, when data was collected for 26 of 31 days, infers that total system output for the full 31 days was approximately 6800 kWh rather than the recorded value of 5782 kWh.

  13. Thermodynamic properties of the intermediate phases of the Ag-Sb-Se system

    NASA Astrophysics Data System (ADS)

    Moroz, M. V.; Prokhorenko, M. V.

    2014-05-01

    The emf (ɛ) dependence of C|Ag|AgI|glass Ag2GeS3| D|C galvanic elements on temperature is studied in the range of 470 to 575 K (C represents current electrodes, D denotes equilibrium three-phase alloys of individual Ag-Sb-Se systems, and AgI|glass Ag2GeS3 is a bilayer membrane with purely ionic (Ag+) electroconductivity). Analytical equations ɛ = ɛ( T) are used to calculate the thermodynamic functions of saturated solid solutions of the AgSbSe2, Sb2Se3, and Ag2Se phases of the Ag-Sb-Se system in the standard state.

  14. 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.

  15. Nonlinear systems for frequency conversion from IR to RF

    NASA Astrophysics Data System (ADS)

    Dolasinski, Brian D.

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

  16. A study of impact of the geographic dependence of observing system on parameter estimation with an intermediate coupled model

    NASA Astrophysics Data System (ADS)

    Wu, Xinrong; Zhang, Shaoqing; Liu, Zhengyu; Rosati, Anthony; Delworth, Thomas L.

    2013-04-01

    Observational information has a strong geographic dependence that may directly influence the quality of parameter estimation in a coupled climate system. Using an intermediate atmosphere-ocean-land coupled model, the impact of geographic dependent observing system on parameter estimation is explored within a "twin" experiment framework. The "observations" produced by a "truth" model are assimilated into an assimilation model in which the most sensitive model parameter has a different geographic structure from the "truth", for retrieving the "truth" geographic structure of the parameter. To examine the influence of data-sparse areas on parameter estimation, the twin experiment is also performed with an observing system in which the observations in some area are removed. Results show that traditional single-valued parameter estimation (SPE) attains a global mean of the "truth", while geographic dependent parameter optimization (GPO) can retrieve the "truth" structure of the parameter and therefore significantly improves estimated states and model predictability. This is especially true when an observing system with data-void areas is applied, where the error of state estimate is reduced by 31 % and the corresponding forecast skill is doubled by GPO compared with SPE.

  17. Frequency control in micro-grid power system combined with electrolyzer system and fuzzy PI controller

    NASA Astrophysics Data System (ADS)

    Li, Xiangjun; Song, Yu-Jin; Han, Soo-Bin

    The widespread use of various kinds of distributed power sources would impact the quality of the power supply within a micro-grid power system, causing many control problems. This paper focuses on the stability of micro-grid operation and discusses the control techniques of combining a micro-turbine with the fuel cell and electrolyzer hybrid system to expand the micro-grid system's ability to solve power quality issues resulting from frequency fluctuations. The paper examines the feasibility of fuel cell and electrolyzer hybrid system control, especially dynamic control of an electrolyzer system, to secure a real power balance and enhance the operational capability of load frequency control. The proposed control and monitoring system can be considered to be a means of power quality control, both to improve the frequency fluctuations caused by random power fluctuations on the generation and load sides and to relax tie-line power flow fluctuations caused by frequency fluctuations in the interconnected micro-grid power system.

  18. Linear Frequency Modulated Signals VS Orthogonal Frequency Division Multiplexing Signals for Synthetic Aperture Radar Systems

    DTIC Science & Technology

    2014-06-01

    frequency modulation (LFM), communications radar 15. NUMBER OF PAGES 161 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT Unclassified 18...116 APPENDIX MATLAB CODES ...........................................................................117 LIST OF...results obtained for the range imaging case and two-dimensional case, respectively. All simulations were conducted in MATLAB , and the code was derived

  19. Cross-matching algorithm for the Intermediate Data Updating system in Gaia

    NASA Astrophysics Data System (ADS)

    Clotet, M.; González-Vidal, J. J.; Castaneda, J.; Garralda, N.; Portell, J.; Fabricius, C.; Torra, J.

    2017-03-01

    Cross Matching (XM) is an inherently difficult problem in astronomy. The assignation of which detection belongs to a given source is a complex issue that has deep implications in further usages of the data. Gaia provides a massive amount of new observations every day which must be linked to sources so that further data reduction can take place. The XM in Gaia provides a consistent match between observations and sources in the working catalogue for subsequent data reduction processes. The system in charge of performing the XM in Gaia is designed in three stages. First the input observations are processed by time in order to compute the sky coordinates and obtain the preliminary source candidates for each individual detection. Then, a second task groups the results to determine isolated groups of detections, avoiding boundary issues. Finally, the relations between the observations and corresponding sources are provided.

  20. Variable association of reactive intermediate genes with systemic lupus erythematosus (SLE) in populations with different African ancestry

    PubMed Central

    Ramos, Paula S.; Oates, James C.; Kamen, Diane L.; Williams, Adrienne H.; Gaffney, Patrick M.; Kelly, Jennifer A.; Kaufman, Kenneth M.; Kimberly, Robert P.; Niewold, Timothy B.; Jacob, Chaim O.; Tsao, Betty P.; Alarcón, Graciela S.; Brown, Elizabeth E.; Edberg, Jeffrey C.; Petri, Michelle A.; Ramsey-Goldman, Rosalind; Reveille, John D.; Vilá, Luis M.; James, Judith A.; Guthridge, Joel M.; Merrill, Joan T.; Boackle, Susan A.; Freedman, Barry I.; Scofield, R. Hal; Stevens, Anne M.; Vyse, Timothy J.; Criswell, Lindsey A.; Moser, Kathy L.; Alarcón-Riquelme, Marta E.; Langefeld, Carl D.; Harley, John B.; Gilkeson, Gary S.

    2013-01-01

    Objective Little is known about the genetic etiology of systemic lupus erythematosus (SLE) in individuals of African ancestry, despite its higher prevalence and greater disease severity. Overproduction of nitric oxide (NO) and reactive oxygen species are implicated in the pathogenesis and severity of SLE, making NO synthases and other reactive intermediate related genes biological candidates for disease susceptibility. This study analyzed variation in reactive intermediate genes for association with SLE in two populations with African ancestry. Methods A total of 244 SNPs from 53 regions were analyzed in non-Gullah African Americans (AA; 1432 cases and 1687 controls) and the genetically more homogeneous Gullah of the Sea Islands of South Carolina (133 cases and 112 controls) and. Single-marker, haplotype, and two-locus interaction tests were computed for these populations. Results The glutathione reductase gene GSR (rs2253409, P=0.0014, OR [95% CI]=1.26 [1.09–1.44]) was the most significant single-SNP association in AA. In the Gullah, the NADH dehydrogenase NDUFS4 (rs381575, P=0.0065, OR [95%CI]=2.10 [1.23–3.59]) and nitric oxide synthase gene NOS1 (rs561712, P=0.0072, OR [95%CI]=0.62 [0.44–0.88]) were most strongly associated with SLE. When both populations were analyzed together, GSR remained the most significant effect (rs2253409, P=0.00072, OR [95%CI]=1.26 [1.10–1.44]). Haplotype and two-locus interaction analyses also uncovered different loci in each population. Conclusion These results suggest distinct patterns of association with SLE in African-derived populations; specific loci may be more strongly associated within select population groups. PMID:23637325

  1. Intermediate-depth ice coring of high-altitude and polar glaciers with a lightweight drilling system

    NASA Astrophysics Data System (ADS)

    Zagorodnov, V.; Thompson, L. G.; Ginot, P.; Mikhalenko, V.

    A total of 11 ice cores to a maximum depth of 460 m have been obtained over the past 3 years from high-altitude glaciers on the saddle of Mount Bona and Mount Churchill in Alaska (designated B C), and on Quelccaya ice cap and Nevado Coropuna in Peru. Ice coring was conducted using an intermediate-depth drilling system. The system includes an electromechanical drill (EMD) and an ethanol thermal electric drill (ETED). The EMD permitted an average ice-core production rate (ICPR) of 7.0 m h-1 down to 150 m. An average ICPR of 2 m h-1 to 460 m depth was possible with the ETED. The quality of the B C ice cores is better than that of cores previously drilled with an EMD and ETED system. A new cutter design, drilling with a lubricant/cutting fluid and a new anti-torque assembly were tested in the laboratory and in glacier boreholes. We examine the performance of the drills in cold and temperate ice and in clean and particle-laden ice. The influence of the ethanol drilling fluid on ice-core isotopic, ionic and dust composition is discussed.

  2. An evaluation of parametric sensitivities of different climatic variables simulated by the Earth System Model of Intermediate Complexity LOVECLIM

    NASA Astrophysics Data System (ADS)

    Shi, Yuhan; Duan, Qingyun

    2017-04-01

    Earth System Models (ESMs) are an important tool for understanding past climate evolution and for predicting future climate change. However, the ESM model outputs contain significant uncertainties. A major source of uncertainties is from the specification of model parameters. Specification of ESM model parameters is complicated as most ESMs contain a large number of model parameters. Further, ESMs simulate many different climatic variables and are computationally expensive to run. In this study, we intend to use a design of experiment approach to evaluate the parametric sensitivities of different climatic variables simulated by LOVECLIM, an Earth System Model of Intermediate Complexity (EMIC). Three sensitivity analysis methods are used to explore the sensitivities of different outputs of LOVECLIM, such as global mean temperature, global land/ocean precipitation and evaporation to different model parameters. A newly developed software package, Uncertainty Quantification Python Laboratory (UQ-PyL), is employed to execute the sensitivity analysis. A total of 23 adjustable parameters of the model were considered. This presentation will present the preliminary results of parameter sensitivity analysis, which, in turn, should form the basis for further optimization of the model parameters to better simulate the climate system.

  3. Striatal response to reward anticipation: evidence for a systems-level intermediate phenotype for schizophrenia.

    PubMed

    Grimm, Oliver; Heinz, Andreas; Walter, Henrik; Kirsch, Peter; Erk, Susanne; Haddad, Leila; Plichta, Michael M; Romanczuk-Seiferth, Nina; Pöhland, Lydia; Mohnke, Sebastian; Mühleisen, Thomas W; Mattheisen, Manuel; Witt, Stephanie H; Schäfer, Axel; Cichon, Sven; Nöthen, Markus; Rietschel, Marcella; Tost, Heike; Meyer-Lindenberg, Andreas

    2014-05-01

    Attenuated ventral striatal response during reward anticipation is a core feature of schizophrenia that is seen in prodromal, drug-naive, and chronic schizophrenic patients. Schizophrenia is highly heritable, raising the possibility that this phenotype is related to the genetic risk for the disorder. To examine a large sample of healthy first-degree relatives of schizophrenic patients and compare their neural responses to reward anticipation with those of carefully matched controls without a family psychiatric history. To further support the utility of this phenotype, we studied its test-retest reliability, its potential brain structural contributions, and the effects of a protective missense variant in neuregulin 1 (NRG1) linked to schizophrenia by meta-analysis (ie, rs10503929). Examination of a well-established monetary reward anticipation paradigm during functional magnetic resonance imaging at a university hospital; voxel-based morphometry; test-retest reliability analysis of striatal activations in an independent sample of 25 healthy participants scanned twice with the same task; and imaging genetics analysis of the control group. A total of 54 healthy first-degree relatives of schizophrenic patients and 80 controls matched for demographic, psychological, clinical, and task performance characteristics were studied. Blood oxygen level-dependent response during reward anticipation, analysis of intraclass correlations of functional contrasts, and associations between striatal gray matter volume and NRG1 genotype. Compared with controls, healthy first-degree relatives showed a highly significant decrease in ventral striatal activation during reward anticipation (familywise error-corrected P < .03 for multiple comparisons across the whole brain). Supplemental analyses confirmed that the identified systems-level functional phenotype is reliable (with intraclass correlation coefficients of 0.59-0.73), independent of local gray matter volume (with no

  4. A frequency scanning method for the identification of harmonic instabilities in HVDC systems

    SciTech Connect

    Jiang, X.; Gole, A.M.

    1995-10-01

    A Frequency Scanning Method is introduced in the paper to obtain a more accurate frequency characteristic for identifying harmonic instability in HVdc systems. An example of the application is used to identify the resonance frequencies in the CIGRE benchmark model. The paper shows that the Benchmark model is not tuned to the resonance frequency that it was designed for. Using the scanning method, the resonance frequency of the benchmark model may be shifted to demonstrate a simulation of core-saturation type instability.

  5. Microstructural engineering of composite cathode systems for intermediate and low-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Camaratta, Matthew

    Solid oxide fuel cells (SOFCs) are electrochemical devices with the potential to generate power at high efficiency with little environmental impact. However, in order to improve their commercial appeal, operating temperatures must be lowered from the 800-1000°C temperature range to 500-700°C and below. Due to the high bond strength of oxygen molecules, the kinetics of oxygen reduction are orders of magnitude slower than those of fuel oxidation. Consequently, much research in the reduced-temperature SOFC field is aimed at enhancing cathode performance. A composite cathode makes use of an electronic conducting phase as well as an ion conducting phase in order to spread the 3PB reaction zone beyond the cathode/electrolyte interface. Silver-stabilized bismuth oxide composite cathodes exhibit low resistance to oxygen reduction due to a combination of high catalytic activity for oxygen reduction of both phases, as well as high ionic conductivity of the bismuth oxide phase. Isothermal comparisons were made between pure silver cathodes, silver-yttrium stabilized bismuth oxide (YSB) cathodes, and silver-erbium stabilized bismuth oxides (ESB) at 650°C. The performance of all cathodes was shown to degrade with time. Cathode area specific resistance (ASR) of both the Ag-YSB and Ag-ESB electrodes increased by around 70%, while the pure Ag system experienced a near fourfold increase during the same length of time under open circuit conditions. In light of the electrochemical, microstructural, and chemical evidence presented, it was concluded that electrode microstructural evolution due to growth, agglomeration, and coalescence of the silver phase, rather than chemical reactivity of the bismuth oxide phase, was responsible for the observed degradation in electrochemical performance. Attempts were made to reduce the microstructural evolution of the silver phase in Ag-ESB20 composites by introduction of small particles (nano-size 8YSZ or vibratory-milled ESB20 particles) into

  6. Analog Techniques for Measuring the Frequency Response of Linear Physical Systems Excited by Frequency-Sweep Inputs

    NASA Technical Reports Server (NTRS)

    Reed, Wilmer H., III; Hall, Albert W.; Barker, Lawrence E., Jr.

    1960-01-01

    Data-reduction methods using general-purpose analog computer equipment and compatible testing techniques for determining the frequency response of linear physical systems are examined. The techniques considered may be classed as steady state or transient depending on the method of excitation. The relative merits of periodic, slow sweep, and transient (rapid sweep) forcing functions are discussed and applications are given that relate to dynamic-response tests of aeroelastic systems. Two frequency-sweep-input methods are considered in detail. one case the sweep rate is sufficiently slow that the response is approximately the same as that for steady-state conditions. With this input the frequency response can be evaluated and displayed in real time while the test is in progress. Errors due to treating sweep data as steady state can be eliminated, when desired, by reanalyzing tape-recorded time histories of the input and output as transient rather than as periodic data. In the second method the frequency-response function is deter- mined from the system's transient response to a very rapid sweep input. The purpose of frequency sweep in this case is to provide sufficient harmonic content in the input to overcome noise while keeping the test time as short as possible. tests and limited flight-test data presented herein, it appears that a transient-type rapid-sweep forcing function offers a considerable saving in test time while preserving the accuracy possible with steady-state sinusoidal inputs.

  7. 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).

  8. Planck intermediate results. VII. Statistical properties of infrared and radio extragalactic sources from the Planck Early Release Compact Source Catalogue at frequencies between 100 and 857 GHz

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Argüeso, F.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bethermin, M.; Bhatia, R.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Cabella, P.; Cardoso, J.-F.; Catalano, A.; Cayón, L.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colafrancesco, S.; Colombi, S.; Colombo, L. P. L.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Fosalba, P.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Jaffe, T. R.; Jaffe, A. H.; Jagemann, T.; Jones, W. C.; Juvela, M.; Keihänen, E.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurinsky, N.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Lilje, P. B.; López-Caniego, M.; Macías-Pérez, J. F.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Mitra, S.; Miville-Deschènes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sajina, A.; Sandri, M.; Savini, G.; Scott, D.; Smoot, G. F.; Starck, J.-L.; Sudiwala, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Türler, M.; Valenziano, L.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; White, M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2013-02-01

    We make use of the Planck all-sky survey to derive number counts and spectral indices of extragalactic sources - infrared and radio sources - from the Planck Early Release Compact Source Catalogue (ERCSC) at 100 to 857 GHz (3 mm to 350 μm). Three zones (deep, medium and shallow) of approximately homogeneous coverage are used to permit a clean and controlled correction for incompleteness, which was explicitly not done for the ERCSC, as it was aimed at providing lists of sources to be followed up. Our sample, prior to the 80% completeness cut, contains between 217 sources at 100 GHz and 1058 sources at 857 GHz over about 12 800 to 16 550 deg2 (31 to 40% of the sky). After the 80% completeness cut, between 122 and 452 and sources remain, with flux densities above 0.3 and 1.9 Jy at 100 and 857 GHz. The sample so defined can be used for statistical analysis. Using the multi-frequency coverage of the Planck High Frequency Instrument, all the sources have been classified as either dust-dominated (infrared galaxies) or synchrotron-dominated (radio galaxies) on the basis of their spectral energy distributions (SED). Our sample is thus complete, flux-limited and color-selected to differentiate between the two populations. We find an approximately equal number of synchrotron and dusty sources between 217 and 353 GHz; at 353 GHz or higher (or 217 GHz and lower) frequencies, the number is dominated by dusty (synchrotron) sources, as expected. For most of the sources, the spectral indices are also derived. We provide for the first time counts of bright sources from 353 to 857 GHz and the contributions from dusty and synchrotron sources at all HFI frequencies in the key spectral range where these spectra are crossing. The observed counts are in the Euclidean regime. The number counts are compared to previously published data (from earlier Planck results, Herschel, BLAST, SCUBA, LABOCA, SPT, and ACT) and models taking into account both radio or infrared galaxies, and covering a

  9. 47 CFR 90.357 - Frequencies for LMS systems in the 902-928 MHz band.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for LMS systems in the 902-928 MHz... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.357 Frequencies for LMS systems in the 902-928 MHz band. (a) Multilateration LMS systems will be...

  10. 47 CFR 90.357 - Frequencies for LMS systems in the 902-928 MHz band.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.357 Frequencies for LMS systems in the 902-928 MHz band. (a) Multilateration LMS systems will be... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequencies for LMS systems in the 902-928 MHz...

  11. 47 CFR 90.357 - Frequencies for LMS systems in the 902-928 MHz band.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.357 Frequencies for LMS systems in the 902-928 MHz band. (a) Multilateration LMS systems will be... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies for LMS systems in the 902-928 MHz...

  12. 47 CFR 90.357 - Frequencies for LMS systems in the 902-928 MHz band.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.357 Frequencies for LMS systems in the 902-928 MHz band. (a) Multilateration LMS systems will be... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequencies for LMS systems in the 902-928...

  13. Histamine Immunoreactive Elements in the Central and Peripheral Nervous Systems of the Snail, Biomphalaria spp., Intermediate Host for Schistosoma mansoni.

    PubMed

    Habib, Mohamed R; Mohamed, Azza H; Osman, Gamalat Y; Sharaf El-Din, Ahmed T; Mossalem, Hanan S; Delgado, Nadia; Torres, Grace; Rolón-Martínez, Solymar; Miller, Mark W; Croll, Roger P

    2015-01-01

    Histamine appears to be an important transmitter throughout the Animal Kingdom. Gastropods, in particular, have been used in numerous studies establishing potential roles for this biogenic amine in the nervous system and showing its involvement in the generation of diverse behaviours. And yet, the distribution of histamine has only previously been described in a small number of molluscan species. The present study examined the localization of histamine-like immunoreactivity in the central and peripheral nervous systems of pulmonate snails of the genus Biomphalaria. This investigation demonstrates immunoreactive cells throughout the buccal, cerebral, pedal, left parietal and visceral ganglia, indicative of diverse regulatory functions in Biomphalaria. Immunoreactivity was also present in statocyst hair cells, supporting a role for histamine in graviception. In the periphery, dense innervation by immunoreactive fibers was observed in the anterior foot, perioral zone, and other regions of the body wall. This study thus shows that histamine is an abundant transmitter in these snails and its distribution suggest involvement in numerous neural circuits. In addition to providing novel subjects for comparative studies of histaminegic neurons in gastropods, Biomphalaria is also the major intermediate host for the digenetic trematode parasite, which causes human schistosomiasis. The study therefore provides a foundation for understanding potential roles for histamine in interactions between the snail hosts and their trematode parasites.

  14. 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.

  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. An ultra-broadband low-frequency magnetic resonance system

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. Application of multi-variable control for automatic frequency controller of HVDC transmission system

    SciTech Connect

    Sanpei, Masatoshi ); Kakehi, Atsuyuki; Takeda, Hideo )

    1994-04-01

    In an HVDC transmission system that links two ac power systems, the automatic frequency controller (AFC) calculates power to be interchanged between the two ac systems according to their frequencies thereby improving the frequency characteristics of the two power systems. This paper introduces a newly developed dc AFC system, which applies a multi-variable control to the dc system-based frequency control. It is capable of controlling the frequencies of the two ac systems optimally while maintaining their stability. This system was developed for one of Japan's HVDC transmission facilities and produced good results in a combined test using a power system simulator. The field installation will be completed in March 1993, when the AFC system will enter service.

  18. Enzymatic synthesis of an ezetimibe intermediate using carbonyl reductase coupled with glucose dehydrogenase in an aqueous-organic solvent system.

    PubMed

    Liu, Zhi-Qiang; Dong, Si-Chuan; Yin, Huan-Huan; Xue, Ya-Ping; Tang, Xiao-Ling; Zhang, Xiao-Jian; He, Jun-Yao; Zheng, Yu-Guo

    2017-04-01

    (4S)-3-[(5S)-5-(4-Fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one ((S)-ET-5) is an important chiral intermediate in the synthesis of chiral side chain of ezetimibe. Recombinant Escherichia coli expressing carbonyl reductase (CBR) was successfully constructed in this study. The total E. coli biomass and the specific activity of recombinant CBR in 5L fermenter culture were 10.9gDCWL(-1) and 14900.3Ug(-1)DCW, respectively. The dual-enzyme coupled biocatalytic process in an aqueous-organic biphasic solvent system was first constructed using p-xylene as the optimal organic phase under optimized reaction conditions, and 150gL(-1) (4S)-3-[5-(4-fluorophenyl)-1,5-dioxophentyl]-4-phenyl-1,3-oxazolidin-2-one (ET-4) was successfully converted to (S)-ET-5 with a conversion of 99.1% and diastereomeric excess of 99% after 24-h, which are the highest values reported to date for the production of (S)-ET-5.

  19. Intermediate-coupling scheme for many-electron systems of the complexes of the transition-metal ions

    NASA Astrophysics Data System (ADS)

    Basu, S.; Chakravarty, A. S.

    1982-10-01

    The generalized theory of the intermediate-coupling scheme has been developed for the many-electron systems of the second and third series of the transition-metal-ion octahedral complexes. The theory has been developed for the general configuration, kdn (k=3, 4, 5 n=2, ..., 9) but has been presented up to n=5. The transformation matrices for the remaining d10-n(n<5) configurations can be easily found from those of dn(n<5) by using the well-known principle of electron-hole complimentarity. To show the enormous simplicity and great advantage over the strong-field coupling scheme so long used in such cases, the d3 configuration has been treated by this method as an application. At the end some typical magnitudes of the parameters like Dq, ζ, B, and C have been used to find the energy levels and the paramagnetic susceptibility for K2ReCl6. The beauty and importance of this scheme lies in the fact that as one switches off the spin-orbit interaction one gets results identical with those of Tanabe and Sugano, and further, if one also switches off the crystal field but retains only the interelectronic repulsion term one gets the results coinciding with those of Racah in atomic spectroscopy.

  20. Intermediate photovoltaic system application experiment operational performance report for G. N. Wilcox Memorial Hospital, Kauai, Hawaii, for November 1982

    SciTech Connect

    Not Available

    1982-01-01

    The data accumulated during November 1982 at the intermediate photovoltaic project at G.N. Wilcox Memorial Hospital, Kauai, Hawaii, are presented. Generated energy and environmental (weather) data are presented graphically. Explanations of irregularities not attributable to weather are provided.

  1. 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.

  2. 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.

  3. Advancements in frequency-domain methods for rotorcraft system identification

    NASA Technical Reports Server (NTRS)

    Tischler, Mark B.

    1989-01-01

    A new method for frequency-domain identification of rotorcraft dynamics is presented. Nonparametric frequency-response identification and parametric transfer-function modeling methods are extended to allow the extraction of state-space (stability and control derivative) representations. An interactive computer program DERIVID is described for the iterative solution of the multi-input/multi-output frequency-response matching approach used in the identification. Theoretical accuracy methods are used to determine the appropriate model structure and degree-of-confidence in the identified parameters. The method is applied to XV-15 tilt-rotor aircraft data in hover. Bare-airframe stability and control derivatives for the lateral/directional dynamics are shown to compare favorably with models previously obtained using time-domain identification methods and the XV-15 simulation program.

  4. Advancements in frequency-domain methods for rotorcraft system identification

    NASA Technical Reports Server (NTRS)

    Tischler, Mark B.

    1988-01-01

    A new method for frequency-domain identification of rotorcraft dynamics is presented. Nonparametric frequency-response identification and parametric tranfer-function modeling methods are extended to allow the extraction of state-space (stability and control derivative) representations. An interactive computer program DERIVID is described for the iterative solution of the multi-input/multi-output frequency-response matching approach used in the identification. Theoretical accuracy methods are used to determine the appropriate model structure and degree-of-confidence in the identified parameters. The method is applied to XV-15 tilt-rotor aircraft data in hover. Bare-airframe stability and control derivatives for the lateral/directional dynamics are shown to compare favorably with models previously obtained using time-domain identification methods and the XV-15 simulation program.

  5. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... System (AMTS) and for other automated multi-station systems. (a) Automated Maritime Telecommunications System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... stations for public correspondence communications with ship stations and units on land. AMTS...

  6. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... System (AMTS) and for other automated multi-station systems. (a) Automated Maritime Telecommunications System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... stations for public correspondence communications with ship stations and units on land. AMTS...

  7. 47 CFR 80.385 - Frequencies for automated systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... System (AMTS) and for other automated multi-station systems. (a) Automated Maritime Telecommunications System (AMTS). (1) The Automated Maritime Communications System (AMTS) is an automated maritime... stations for public correspondence communications with ship stations and units on land. AMTS...

  8. 77 FR 52317 - Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active Sonar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active... Array Sensor System Low Frequency Active (SURTASS LFA) sonar systems with certain...

  9. 47 CFR 80.383 - Vessel Traffic Services (VTS) system frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Vessel Traffic Services (VTS) system... SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Vessel Traffic Services System (vts) § 80.383 Vessel Traffic Services (VTS) system frequencies. This section describes the...

  10. 47 CFR 80.383 - Vessel Traffic Services (VTS) system frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Vessel Traffic Services (VTS) system... SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Vessel Traffic Services System (vts) § 80.383 Vessel Traffic Services (VTS) system frequencies. This section describes the...

  11. 47 CFR 80.383 - Vessel Traffic Services (VTS) system frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Vessel Traffic Services (VTS) system... SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Vessel Traffic Services System (vts) § 80.383 Vessel Traffic Services (VTS) system frequencies. This section describes the...

  12. 47 CFR 80.383 - Vessel Traffic Services (VTS) system frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Vessel Traffic Services (VTS) system... SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Vessel Traffic Services System (vts) § 80.383 Vessel Traffic Services (VTS) system frequencies. This section describes the...

  13. System design and reliability considerations for an intermediate-size photovoltaic power system for a remote application

    NASA Astrophysics Data System (ADS)

    Noel, G. T.; Stember, L. H.; Carmichael, D. C.

    The design of a photovoltaic power system for remote applications is described. The preliminary requirements placed on the system are high reliability of power and low life-cycle cost, considering equipment, remote installation, and operation and maintenance costs. The design incorporates flat-panel modules assembled onto steel frames and prewired prior to shipment to the site, in order to minimize on-site installation costs, skilled labor requirements, and risk of costly delays and failures. Other components include power conditioning units, battery storage, battery charger, back-up diesel generators, and controls. A methodology for system reliability analysis using the fault-tree technique is illustrated to aid in system design, and an assessment is made of mean time between failures (MTBF), mean time to restore/repair (MTTR), and system availability.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Student Response Systems in the College Classroom: An Investigation of Short-Term, Intermediate, and Long-Term Recall of Facts

    ERIC Educational Resources Information Center

    Blood, Erika

    2012-01-01

    The effects of student response system (SRS) use during lecture-style instruction on short-term, intermediate, and long-term retention of facts was investigated in an undergraduate teacher preparation course. Participants were undergraduate students enrolled in a special education initial certification program. Student performance on quizzes and…

  19. Higher-order modulations of fs laser pulses for GHz frequency domain photon migration system.

    PubMed

    Lin, Huang-Yi; Cheng, Nanyu; Tseng, Sheng-Hao; Chan, Ming-Che

    2014-02-24

    Except the fundamental modulation frequency, by higher-order-harmonic modulations of mode-locked laser pulses and a simple frequency demodulation circuit, a novel approach to GHz frequency-domain-photon-migration (FDPM) system was reported. With this novel approach, a wide-band modulation frequency comb is available without any external modulation devices and the only electronics to extract the optical attenuation and phase properties at a selected modulation frequency in FDPM systems are good mixers and lock-in devices. This approach greatly expands the frequency range that could be achieved by conventional FDPM systems and suggests that our system could extract much more information from biological tissues than the conventional FDPM systems. Moreover, this demonstration will be beneficial for discerning the minute change of tissue properties.

  20. Linear Optimization of Frequency Spectrum Assignments Across System

    DTIC Science & Technology

    2016-03-01

    selection tools, frequency allocation, transmission optimization, electromagnetic maneuver warfare, electronic protection, assignment model 15. NUMBER... ELECTROMAGNETIC MANEUVER WARFARE .............................5  B.  THE SPECTRUM AS THE NEWEST DOMAIN ..................................6  C.  A FULL...concept AW air warfare CM communications CNO Chief of Naval Operations DT data transmission EA electronic attack EME electromagnetic

  1. Carrier-frequency synchronization system for improved amplitude modulation and television broadcast reception

    DOEpatents

    Smith, Stephen F.; Moore, James A.

    2003-05-13

    Systems and methods are described for carrier-frequency synchronization for improved AM and TV broadcast reception. A method includes synchronizing a carrier frequency of a broadcast signal with a remote reference frequency. An apparatus includes a reference signal receiver; a phase comparator coupled to the reference signal receiver; a voltage controlled oscillator coupled to the phase comparator; and a radio frequency output coupled to the voltage controlled oscillator.

  2. An expert system to analyze high frequency dependent data for the space shuttle main engine turbopumps

    NASA Technical Reports Server (NTRS)

    Garcia, Raul C., Jr.

    1987-01-01

    The prototype expert system ADDAMX identifies selected sinusoid frequencies from spectral data graphs as speed frequencies and harmonics from each turbopump, frequency feed through from one turbopump to another, frequencies generated by turbopump bearings, pseudo 3N for the phase 2 high pressure fuel turbopump, and electrical noise. ADDAMX does the analysis in an interactive or batch mode and the results can be displayed on the screen or hardcopy.

  3. Propagation effects on satellite systems at frequencies below 10 GHz: A handbook for satellite systems design

    NASA Technical Reports Server (NTRS)

    Flock, Warren L.

    1987-01-01

    Frequencies below 10 GHz continue to be used for a large portion of satellite service, and new applications, including mobile satellite service and the global positioning system, use frequencies below 10 GHz. As frequency decreases below 10 GHz, attenuation due to precipitation and gases decreases and ionospheric effects increase. Thus the ionosphere, which can be largely neglected above 10 GHz, receives major attention. Although attenuation and depolarization due to rain are less severe below 10 GHz than above, they are nevertheless still important and constitute another major topic. The handbook emphasizes the propagation effects on satellite communications but material that is pertinent to radio navigation and positioning systems and deep-space telecommunications is included as well. Chapter 1 through 7 describe the various propagation impairments, and Chapter 9 is devoted to the estimation or calculation of the magnitudes of these effects for use in system design. Chapter 10 covers link power budget equations and the role of propagation effects in these equations. Chapter 8 deals with the complex subject of interference between space and terrestrial systems.

  4. Systemic Thrombolysis, Catheter-Directed Thrombolysis and Anticoagulation for Intermediate-Risk Pulmonary Embolism: A Simulation Modeling Analysis.

    PubMed

    Kabrhel, Christopher; Ali, Ayman; Choi, Jin; Hur, Chin

    2017-06-26

    Decision-making around the use of thrombolysis for patients with intermediate-risk (submassive) PE remains challenging. Studies indicate favorable clinical outcomes with systemic thrombolytics (IV tPA), but the risk of major bleeding and hemorrhagic stroke is a deterrent. Catheter-directed thrombolysis (CDT) may be a preferable strategy, as it has been shown to have a lower risk of bleeding than systemic thrombolysis. However, a three-arm randomized control study comparing IV tPA, CDT, and anticoagulation alone, with long-term follow up, would be costly and is unlikely to be performed. The aim of this study was to use decision modeling to quantitatively estimate the differences between the three strategies. We created an individual level state-transition model to simulate long-term outcomes of a hypothetical patient cohort treated with either IV tPA, CDT or anticoagulation alone. Our model incorporated clinical RCT and longitudinal study data to inform patient characteristics and outcomes specific to each study arm. The base case was a 65 year old patient. Additionally, we utilized preliminary data published by the Pulmonary Embolism Response Team (PERT) at the Massachusetts General Hospital. Variance in model inputs was addressed with deterministic and probabilistic sensitivity analyses. Our primary endpoint was quality-adjusted life years (QALYs). Secondary endpoints included total cost and incremental cost-effectiveness ratios (ICER). CDT (mean, 95% confidence interval) [7.388 (7.381, 7.396) QALYs] resulted in the most long-term utility for eligible patients compared to anticoagulation alone [7.352 (7.345, 7.360) QALYs] or IV tPA [7.343 (7.336, 7.351) QALYs]. Patients receiving CDT had an elevated risk of hemorrhagic stroke in comparison to anticoagulation alone; however, patients treated with anticoagulation alone were more likely to experience recurrent PE associated adverse outcomes. Results were stable with sensitivity analyses varying age and sex. Our

  5. Frequency measurement of a Sr lattice clock using an SI-second-referenced optical frequency comb linked by a global positioning system (GPS)

    NASA Astrophysics Data System (ADS)

    Hong, Feng-Lei; Takamoto, Masao; Higashi, Ryoichi; Fukuyama, Yasuhiro; Jiang, Jie; Katori, Hidetoshi

    2005-07-01

    We have established a transportable frequency measurement system using an optical frequency comb linked to a commercial Cs atomic clock, which is in turn linked to international atomic time (TAI) through global positioning system (GPS) time. An iodine-stabilized Nd:YAG laser is used as a flywheel in the frequency measurement system. This system is used to measure the absolute frequency of the clock transition of 87Sr in an optical lattice. We obtained a fractional uncertainty of 2×10-14 in the frequency measurement with a total averaging time of ~ 105 s over 9 days.

  6. Frequency measurement of a Sr lattice clock using an SI-second-referenced optical frequency comb linked by a global positioning system (GPS).

    PubMed

    Hong, Feng-Lei; Takamoto, Masao; Higashi, Ryoichi; Fukuyama, Yasuhiro; Jiang, Jie; Katori, Hidetoshi

    2005-07-11

    We have established a transportable frequency measurement system using an optical frequency comb linked to a commercial Cs atomic clock, which is in turn linked to international atomic time (TAI) through global positioning system (GPS) time. An iodine-stabilized Nd:YAG laser is used as a flywheel in the frequency measurement system. This system is used to measure the absolute frequency of the clock transition of (87)Sr in an optical lattice. We obtained a fractional uncertainty of 2x10(-14) in the frequency measurement with a total averaging time of ~ 10(5) s over 9 days.

  7. An efficient frequency response solution for nonproportionally damped systems

    NASA Technical Reports Server (NTRS)

    Conti, Paul; Rule, William K.

    1987-01-01

    A method is presented to accurately and economically calculate steady state frequency responses based on the analysis of large finite element models with nonproportional damping effects. The new method is a hybrid of the traditional nonproportional and proportional damping solution methods. It captures the advantages of each computational approach without the burden of their respective shortcomings, as demonstrated with comparative analysis performed on a large finite element model.

  8. Syntactic Complexity and Frequency in the Neurocognitive Language System.

    PubMed

    Yang, Yun-Hsuan; Marslen-Wilson, William D; Bozic, Mirjana

    2017-09-01

    Prominent neurobiological models of language follow the widely accepted assumption that language comprehension requires two principal mechanisms: a lexicon storing the sound-to-meaning mapping of words, primarily involving bilateral temporal regions, and a combinatorial processor for syntactically structured items, such as phrases and sentences, localized in a left-lateralized network linking left inferior frontal gyrus (LIFG) and posterior temporal areas. However, recent research showing that the processing of simple phrasal sequences may engage only bilateral temporal areas, together with the claims of distributional approaches to grammar, raise the question of whether frequent phrases are stored alongside individual words in temporal areas. In this fMRI study, we varied the frequency of words and of short and long phrases in English. If frequent phrases are indeed stored, then only less frequent items should generate selective left frontotemporal activation, because memory traces for such items would be weaker or not available in temporal cortex. Complementary univariate and multivariate analyses revealed that, overall, simple words (verbs) and long phrases engaged LIFG and temporal areas, whereas short phrases engaged bilateral temporal areas, suggesting that syntactic complexity is a key factor for LIFG activation. Although we found a robust frequency effect for words in temporal areas, no frequency effects were found for the two phrasal conditions. These findings support the conclusion that long and short phrases are analyzed, respectively, in the left frontal network and in a bilateral temporal network but are not retrieved from memory in the same way as simple words during spoken language comprehension.

  9. Radio frequency systems for present and future accelerators

    SciTech Connect

    Raka, E.C.

    1987-01-01

    Rf systems are described for the FNAL Main Ring and Tevatron Ring, CERN SPS and LEP, and HERA proton acceleration system, CERN PS e/sup +/e/sup minus/ acceleration system, and CERN EPA monochromatic cavity. Low impedance rf systems in CERN ISR, the Brookhaven CBA, and SSC are also discussed.

  10. Novel solutions to low-frequency problems with geometrically designed beam-waveguide systems

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Esquivel, M. S.; Manshadi, F.

    1995-01-01

    The poor low-frequency performance of geometrically designed beam-waveguide (BWG) antennas is shown to be caused by the diffraction phase centers being far from the geometrical optics mirror focus, resulting in substantial spillover and defocusing loss. Two novel solutions are proposed: (1) reposition the mirrors to focus low frequencies and redesign the high frequencies to utilize the new mirror positions, and (2) redesign the input feed system to provide an optimum solution for the low frequency. A novel use of the conjugate phase-matching technique is utilized to design the optimum low-frequency feed system, and the new feed system has been implemented in the JPL research and development BWG as part of a dual S-/X-band (2.3 GHz/8.45 GHz) feed system. The new S-band feed system is shown to perform significantly better than the original geometrically designed system.

  11. Optical Reflection Measurement System Using A Swept Modulation Frequency Technique

    NASA Astrophysics Data System (ADS)

    Braun, David M.; Leyde, Kent W.

    1989-03-01

    A measurement system has been developed capable of mea-suring reflected optical power as low as 0.0025% with a spot size diam-eter of 24 Am. One application for this system is the characterization of small-area photodetectors. The operation of the measurement system is simple, allowing the operator to quickly make multiple reflection measurements, and it does not require a darkroom. The measurement system merges a microscope, for visual alignment and focusing of the laser beam, with a lightwave component analyzer using modulation vec-tor error correction. A measurement comparison between the analyzer-based system and a power-meter-based system showed that each sys-tem can measure reflections as low as 0.0025%. However, the analyzer-based system offers the advantage of identifying the location and magnitude of system reflections. The system operates at a wavelength of 1310 nm.

  12. Evaluating key parameters for the initiation of a Neoproterozoic Snowball Earth with a single Earth System Model of intermediate complexity

    NASA Astrophysics Data System (ADS)

    Spiegl, T. C.; Paeth, H.; Frimmel, H. E.

    2015-04-01

    Even after more than two decades of intense research the main drivers for a potential Neoproterozoic Snowball Earth continue to be discussed controversially. In this study we present results from 37 sensitivity experiments that were performed with the Planet Simulator (PlaSim), an Earth System Model of intermediate complexity. In contrast to previous studies, in which only a limited number of potential climate-controlling parameters were assessed with different climate models, we tested our presumed key parameters within one single model. This approach makes it easier to compare the influence of the various parameters on extreme climate change as postulated for the Neoproterozoic Era. Furthermore we compare the results obtained to most recent high complexity state-of-the-art approaches. This comparison helps to estimate, which internal model interactions and physics are crucial for a Snowball Earth simulation and hence should be included into a model that is capable of realistically simulating a Neoproterozoic climate. To this effect we carried out simulations that involved reduced solar irradiation, land-sea distributions, atmospheric CO2 concentrations, relief of the land surface and length of day. In addition, we focus on different land surface albedo values, which were most likely exceptionally low and similar to the Martian albedo, and obliquity changes between 23.5° and 80°. Our findings suggest that changes in land surface albedo are a strong climate driver that can compensate a much lower Neoproterozoic total solar irradiance if it is combined with shifts in obliquity or atmospheric CO2 levels. We also obtained a critical threshold for increased obliquities beyond which a Snowball Earth situation turns into an extreme greenhouse climate with almost absent cryosphere, and furthermore, obliquity values that lead to a tropical ice age with sea ice spreading from the equator to high latitudes.

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

    NASA Astrophysics Data System (ADS)

    Wu, Yipeng; Qiu, Jinhao; Ji, Hongli

    2016-11-01

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

  14. Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y-Ba-Co-O system

    NASA Astrophysics Data System (ADS)

    Urusova, A. S.; Cherepanov, V. A.; Aksenova, T. V.; Gavrilova, L. Ya.; Kiselev, E. A.

    2013-06-01

    The phase equilibria in the Y-Ba-Co-O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y-Ba-Co-O system at 1373 K in air were: YBaCo2O5+δ, YBaCo4O7 and BaCo1-yYyO3-δ (0.09≤y≤0.42). It was shown that YBaCo2O5+δ possesses tetragonal structure with the 3ap×3ap×2ap superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo2O5+δ in the temperature range from 298 K up to 1073 K under Po2=0.21 аtm has not shown any phase transformations. The value of oxygen content for the YBaCo2O5+δ at room temperature was estimated as 5.40 and at 1323 K it was equal to 5.04. Thermal expansion of sample shows a linear characteristics and the average thermal expansion coefficient (TEC) is about 13.8×10-6, K-1 in the temperature range 298-1273 K. The homogeneity range and crystal structure of the BaCo1-yYyO3-δ (0.09≤y≤0.42) solid solutions were determined by X-ray diffraction of quenched samples. All BaCo1-yYyO3-δ solid solutions were found to have cubic structure (sp. gr. Pm3m). The unit cell parameters were refined using Rietveld full-profile analysis. Oxygen nonstoichiometry of BaCo1-yYyO3-δ solid solutions with 0.1≤y≤0.4 was measured by means of thermogravimetric technique within the temperature range 298-1373 K in air. Thermal expansion of BaCo1-yYyO3-δ (у=0.0; 0.1; 0.2; 0.3) samples was studied within the temperature range 298-1200 K in air. The projection of isothermal-isobaric phase diagram for the Y-Ba-Co-O system to the compositional triangle of metallic components was presented.

  15. Formulation of frequency stability limited by laser intrinsic noise in feedback systems.

    PubMed

    Hori, Teruhito; Araya, Akito; Moriwaki, Shigenori; Mio, Norikatsu

    2009-01-10

    We investigated the influence of amplitude modulation (AM) noise and phase modulation (PM) noise of a laser source on the frequency stability in frequency stabilization systems. We estimated the frequency stability and evaluated the efficacy of a noise reduction technique (the Doppler-trend subtraction method) of a laser diode frequency stabilization system, where enhanced intensity noise arising from PM-to-AM noise conversion through a reference gas cell is reduced using the technique employed in modulation transfer spectroscopy. To evaluate the relationship between the laser's intrinsic noise and its frequency stability, we performed noise spectrum measurements and formulated frequency stability in addition to measuring Allan standard deviation. As a result, it is found that the extra noise generated in PM-to-AM conversion is efficiently removed by the Doppler-trend subtraction method and that within the feedback bandwidth, the frequency stability becomes 1 order of magnitude better than that without the method.

  16. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    NASA Astrophysics Data System (ADS)

    Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

    2015-10-01

    Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

  17. Influence of the viscoelastic properties of the respiratory system on the energetically optimum breathing frequency.

    PubMed

    Bates, J H; Milic-Emili, J

    1993-01-01

    We hypothesized that the viscoelastic properties of the respiratory system should have significant implications for the energetically optimal frequency of breathing, in view of the fact that these properties cause marked dependencies of overall system resistance and elastance on frequency. To test our hypothesis we simulated two models of canine and human respiratory system mechanics during sinusoidal breathing and calculated the inspiratory work (WI) and pressure-time integral (PTI) per minute under both resting and exercise conditions. The two models were a two-compartment viscoelastic model and a single-compartment model. Requiring minute alveolar ventilation to be fixed, we found that both models predicted almost identical optimum breathing frequencies. The calculated PTI was very insensitive to increases in breathing frequency above the optimal frequencies, while WI was found to increase slowly with frequency above its optimum. In contrast, both WI and PTI increased sharply as frequency decreased below their respective optima. A sensitivity analysis showed that the model predictions were very insensitive to the elastance and resistance values chosen to characterize tissue viscoelasticity. We conclude that the WI criterion for choosing the frequency of breathing is compatible with observations in nature, whereas the optimal frequency predictions of the PTI are rather too high. Both criteria allow for a fairly wide margin of choice in frequency above the optimum values without incurring excessive additional energy expenditure. Furthermore, contrary to our expectations, the viscoelastic properties of the respiratory system tissues do not pose a noticeable problem to the respiratory controller in terms of energy expenditure.

  18. Gramian-Preserving Frequency Transformation for Linear Discrete-Time State-Space Systems

    NASA Astrophysics Data System (ADS)

    Koshita, Shunsuke; Tanaka, Satoru; Abe, Masahide; Kawamata, Masayuki

    This paper proposes the Gramian-preserving frequency transformation for linear discrete-time state-space systems. In this frequency transformation, we replace each delay element of a discrete-time system with an allpass system that has a balanced realization. This approach can generate transformed systems that have the same controllability/observability Gramians as those of the original system. From this result, we show that the Gramian-preserving frequency transformation gives us transformed systems with different magnitude characteristics, but with the same structural property with respect to the Gramians as that of the original system. This paper also presents a simple method for realization of the Gramian-preserving frequency transformation. This method makes use of the cascaded normalized lattice structure of allpass systems.

  19. Frequency domain analysis and synthesis of lumped parameter systems using nonlinear least squares techniques

    NASA Technical Reports Server (NTRS)

    Hays, J. R.

    1969-01-01

    Lumped parametric system models are simplified and computationally advantageous in the frequency domain of linear systems. Nonlinear least squares computer program finds the least square best estimate for any number of parameters in an arbitrarily complicated model.

  20. The NASA/JPL three-frequency polarimetric AIRSAR system

    NASA Technical Reports Server (NTRS)

    Van Zyl, J.; Carande, R.; Lou, Y.; Miller, T.; Wheeler, K.

    1992-01-01

    The NASA/Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL AIRSAR) system has now completed four flight campaigns. The authors describe the current state of this system and provide insight into how flight seasons are planned for this instrument. The data processors and data products are described. A table containing relevant system parameters is provided.

  1. System upgrades and performance evaluation of the spectrally agile, frequency incrementing reconfigurable (SAFIRE) radar system

    NASA Astrophysics Data System (ADS)

    Phelan, Brian R.; Ranney, Kenneth I.; Ressler, Marc A.; Clark, John T.; Sherbondy, Kelly D.; Kirose, Getachew A.; Harrison, Arthur C.; Galanos, Daniel T.; Saponaro, Philip J.; Treible, Wayne R.; Narayanan, Ram M.

    2017-05-01

    The U.S. Army Research Laboratory has developed the Spectrally Agile Frequency-Incrementing Reconfigurable (SAFIRE) radar, which is capable of imaging concealed/buried targets using forward- and side-looking configurations. The SAFIRE radar is vehicle-mounted and operates from 300 MHz-2 GHz; the step size can be adjusted in multiples of 1 MHz. It is also spectrally agile and capable of excising frequency bands, which makes it ideal for operation in congested and/or contested radio frequency (RF) environments. Furthermore, the SAFIRE radar receiver has a super-heterodyne architecture, which was designed so that intermodulation products caused by interfering signals could be easily filtered from the desired received signal. The SAFIRE system also includes electro-optical (EO) and infrared (IR) cameras, which can be fused with radar data and displayed in a stereoscopic augmented reality user interface. In this paper, recent upgrades to the SAFIRE system are discussed and results from the SAFIRE's initial field tests are presented.

  2. Frequency-based design of Adaptive Optics systems

    NASA Astrophysics Data System (ADS)

    Agapito, Guido; Battistelli, Giorgio; Mari, Daniele; Selvi, Daniela; Tesi, Alberto; Tesi, Pietro

    2013-12-01

    The problem of reducing the effects of wavefront distortion and structural vibrations inground-based telescopes is addressed within a modal-control framework. The proposed approach aimsat optimizing the parameters of a given modal stabilizing controller with respect to a performance criterionwhich reflects the residual phase variance and is defined on a sampled frequency domain. Thisframework makes it possible to account for turbulence and vibration profiles of arbitrary complexity(even empirical power spectral densities from data), while the controller order can be kept at a desiredvalue. Moreover it is possible to take into account additional requirements, as robustness in the presenceof disturbances whose intensity and frequency profile vary with time. The proposed design procedureresults in solving a minmax problem and can be converted into a linear programming problem withquadratic constraints, for which there exist several standard optimization techniques. The optimizationstarts from a given stabilizing controller which can be either a non-model-based controller (in this caseno identification effort is required), or a model-based controller synthesized by means of turbulence andvibration models of limited complexity. In this sense the approach can be viewed not only as alternative,but also as cooperative with other control design approaches. The results obtained by means of anEnd-to-End simulator are shown to emphasize the power of the proposed method.

  3. Frequency transformation in the auditory lemniscal thalamocortical system.

    PubMed

    Imaizumi, Kazuo; Lee, Charles C

    2014-01-01

    The auditory lemniscal thalamocortical (TC) pathway conveys information from the ventral division of the medial geniculate body to the primary auditory cortex (A1). Although their general topographic organization has been well characterized, functional transformations at the lemniscal TC synapse still remain incompletely codified, largely due to the need for integration of functional anatomical results with the variability observed with various animal models and experimental techniques. In this review, we discuss these issues with classical approaches, such as in vivo extracellular recordings and tracer injections to physiologically identified areas in A1, and then compare these studies with modern approaches, such as in vivo two-photon calcium imaging, in vivo whole-cell recordings, optogenetic methods, and in vitro methods using slice preparations. A surprising finding from a comparison of classical and modern approaches is the similar degree of convergence from thalamic neurons to single A1 neurons and clusters of A1 neurons, although, thalamic convergence to single A1 neurons is more restricted from areas within putative thalamic frequency lamina. These comparisons suggest that frequency convergence from thalamic input to A1 is functionally limited. Finally, we consider synaptic organization of TC projections and future directions for research.

  4. Intermediate photovoltaic system application experiment operational performance report. Volume 1. For G. N. Wilcox Memorial Hospital, Kauai, Hawaii

    SciTech Connect

    Not Available

    1982-09-01

    Presented are the data accumulated during January, February, and March 1982 at the intermediate photovoltaic project at G.N. Wilcox Memorial Hospital, Kauai, Hawaii. Generated energy and environmental (weather) data are presented graphically. Explanations of irregularities not attributable to weather are provided.

  5. Intermediate photovoltaic system application experiment operational performance report. Volume 2 for G. N. Wilcox Memorial Hospital, Kauai, HI

    SciTech Connect

    Not Available

    1982-10-01

    Presented are the data accumulated during April and May 1982 at this intermediate photovoltaic project at G.N. Wilcox Memorial Hospital, Kauai, Hawaii. Generated energy and environmental (weather) data are presented graphically. Explanations of irregularities not attributable to weather are provided.

  6. Intermediate photovoltaic system application experiment operational performance report, for G. N. Wilcox Memorial Hospital, Kauai, Hawaii. Vol. 9

    SciTech Connect

    Not Available

    1983-06-01

    This report presents the data accumulated during January 1983 at the intermediate photovoltaic project at G.N. Wilcox Memorial Hospital, Kauai, Hawaii. Generated energy and environmental (weather) data are presented graphically. Explanations of irregularities not attributable to weather are provided.

  7. Secondary Education Systems and the General Skills of Less- and Intermediate-Educated Adults: A Comparison of 18 Countries

    ERIC Educational Resources Information Center

    Heisig, Jan Paul; Solga, Heike

    2015-01-01

    We investigate the impact of external differentiation and vocational orientation of (lower and upper) secondary education on country variation in the mean numeracy skills of, and skills gaps between, adults with low and intermediate formal qualifications. We use data on 30- to 44-year-olds in 18 countries from the 2011-12 round of the Program for…

  8. A frequency averaging framework for the solution of complex dynamic systems

    PubMed Central

    Lecomte, Christophe

    2014-01-01

    A frequency averaging framework is proposed for the solution of complex linear dynamic systems. It is remarkable that, while the mid-frequency region is usually very challenging, a smooth transition from low- through mid- and high-frequency ranges is possible and all ranges can now be considered in a single framework. An interpretation of the frequency averaging in the time domain is presented and it is explained that the average may be evaluated very efficiently in terms of system solutions. PMID:24910518

  9. A comparative study of frequency offset estimations in real and complex OFDM systems using different algorithms

    NASA Astrophysics Data System (ADS)

    Sahu, Swagatika; Mohanty, Saumendra; Srivastav, Richa

    2013-01-01

    Orthogonal Frequency Division Multiplexing (OFDM) is an emerging multi-carrier modulation scheme, which has been adopted for several wireless standards such as IEEE 802.11a and HiperLAN2, etc. A well-known problem of OFDM is its sensitivity to frequency offset between the transmitted and received carrier frequencies. In (OFDM) system Carrier frequency offsets (CFOs) between the transmitter and the receiver destroy the orthogonality between carriers and degrade the system performance significantly. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal.The conventional algorithms given by P. Moose and Schmidl describes how carrier frequency offset of an OFDM system can be estimated using training sequences. Simulation results show that the improved carrier frequency offset estimation algorithm which uses a complex training sequence for frequency offset estimation, performs better than conventional P. Moose and Schmidl algorithm, which can effectively improve the frequency estimation accuracy and provides a wide acquisition range for the carrier frequency offset with low complexity. This paper introduces the BER comparisons of different algorithms with the Improved Algorithms for different Real and Complex modulations schemes, considering random carrier offsets . This paper also introduces the BER performances with different CFOs for different Real and Complex modulation schemes for the Improved algorithm.

  10. Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y–Ba–Co–O system

    SciTech Connect

    Urusova, A.S.; Cherepanov, V.A. Aksenova, T.V.; Gavrilova, L.Ya.; Kiselev, E.A.

    2013-06-01

    The phase equilibria in the Y–Ba–Co–O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y–Ba–Co–O system at 1373 K in air were: YBaCo₂O5+δ, YBaCo₄O₇ and BaCo1–yYyO3–δ (0.09≤y≤0.42). It was shown that YBaCo₂O5+δ possesses tetragonal structure with the 3aₚ×3aₚ×2aₚ superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo₂O5+δ in the temperature range from 298 K up to 1073 K under Po₂=0.21 atm has not shown any phase transformations. The value of oxygen content for the YBaCo₂O5+δ at room temperature was estimated as 5.40 and at 1323 K it was equal to 5.04. Thermal expansion of sample shows a linear characteristics and the average thermal expansion coefficient (TEC) is about 13.8×10⁻⁶, K⁻¹ in the temperature range 298–1273 K. The homogeneity range and crystal structure of the BaCo1–yYyO3–δ (0.09≤y≤0.42) solid solutions were determined by X-ray diffraction of quenched samples. All BaCo1–yYyO3–δ solid solutions were found to have cubic structure (sp. gr. Pm3m). The unit cell parameters were refined using Rietveld full-profile analysis. Oxygen nonstoichiometry of BaCo1–yYyO3–δ solid solutions with 0.1≤y≤0.4 was measured by means of thermogravimetric technique within the temperature range 298–1373 K in air. Thermal expansion of BaCo1–yYyO3–δ (y=0.0; 0.1; 0.2; 0.3) samples was studied within the temperature range 298–1200 K in air. The projection of isothermal–isobaric phase diagram for the Y–Ba–Co–O system to the compositional triangle of metallic components was presented. - Graphical abstract: A projection of isobaric isothermal phase diagram of the Y–Ba–Co–O system to the metallic components

  11. Modeling of thermoacoustic systems using the nonlinear frequency domain method.

    PubMed

    de Jong, J A; Wijnant, Y H; Wilcox, D; de Boer, A

    2015-09-01

    When modeling thermoacoustic (TA) devices at high amplitude, nonlinear effects such as time-average mass flows, and the generation of higher harmonics can no longer be neglected. Thus far, modeling these effects in TA devices required a generally computationally costly time integration of the nonlinear governing equations. In this paper, a fast one-dimensional nonlinear model for TA devices is presented, which omits this costly time integration by directly solving the periodic steady state. The model is defined in the frequency domain, which eases the implementation of phase delays due to viscous resistance and thermoacoustic heat exchange. As a demonstration, the model is used to solve an experimental standing wave thermoacoustic engine. The obtained results agree with experimental results, as well as with results from a nonlinear time domain model from the literature. The low computational cost of this model opens the possibility to do optimization studies using a nonlinear TA model.

  12. Graphene nanoelectromechanical systems as stochastic-frequency oscillators.

    PubMed

    Miao, Tengfei; Yeom, Sinchul; Wang, Peng; Standley, Brian; Bockrath, Marc

    2014-06-11

    We measure the quality factor Q of electrically driven few-layer graphene drumhead resonators, providing an experimental demonstration that Q ∼ 1/T, where T is the temperature. We develop a model that includes intermodal coupling and tensioned graphene resonators. Because the resonators are atomically thin, out-of-plane fluctuations are large. As a result, Q is mainly determined by stochastic frequency broadening rather than frictional damping, in analogy to nuclear magnetic resonance. This model is in good agreement with experiment. Additionally, at larger drives the resonance line width is enhanced by nonlinear damping, in qualitative agreement with recent theory of damping by radiation of in-plane phonons. Parametric amplification produced by periodic thermal expansion from the ac drive voltage yields an anomalously large line width at the largest drives. Our results contribute toward a general framework for understanding the mechanisms of dissipation and spectral line broadening in atomically thin membrane resonators.

  13. Adaptive SSVEP-based BCI system with frequency and pulse duty-cycle stimuli tuning design.

    PubMed

    Shyu, Kuo-Kai; Chiu, Yun-Jen; Lee, Po-Lei; Liang, Jia-Ming; Peng, Shao-Hwo

    2013-09-01

    This study aims to design a steady state visual evoked potentials (SSVEP) based brain-computer interface (BCI) system with only three electrodes. It is known that low frequency flickering induces more intensive SSVEP, but might cause users feel uncomfortable and easily tired. Therefore, this paper proposes a novel middle/high frequency flickering stimulus. However, users show different SSVEP responses when gazing at the same stimuli. It is improper to design fixed frequency flickering stimuli for all users. This study firstly proposes a strategy to adjust the stimuli frequency for each user that could cause better SSVEP. Moreover, to further enhance the SSVEP, this study incorporates flickering duty-cycle for stimuli design, which has been discussed less for SSVEP-based BCI systems. The proposed system consists of two modes, flicker frequency/duty-cycle selection mode and application mode. The flicker frequency/duty-cycle selection mode obtains two best frequencies between 24 and 36 Hz with their related optimal duty-cycle. Then the system goes into the application mode to control the devices. A new fact that has been found is that the optimal flicker frequency and duty-cycle do not vary with time. It means once the optical flicker frequency and duty-cycle is determined the first time, flicker frequency/duty-cycle selection mode does not need to operate the next time. Furthermore, the phase coding technology is used to extend the one command/one frequency to multi command/one frequency. Experimental results show the proposed system has good performance with average accuracy 95% and average command transfer interval 4.4925 s per command.

  14. Comparison of Bus Frequency Models for Power System Electro-mechanical Simulations

    NASA Astrophysics Data System (ADS)

    Li, Changgang; Yu, Yawei; Sun, Yanli

    2017-05-01

    With more and more frequency-related devices interconnected into power grid, accurate frequency estimation becomes important for power system electro-mechanical simulations. This paper reviewed the methods for calculation of bus frequency including difference method, difference method with low-pass filter. Trapezoidal method and damping trapezoidal method which are commonly used in numerical computation are also discussed in this paper for the calculation of bus frequency. In order to analyze advantages and disadvantages of these methods in the aspect of numerical accuracy and stability, a comparison is made on their amplitude-frequency and phase-frequency characteristics. Voltage angle samples from both ideal function and numerical simulation are provided to test the performance of these methods on estimating bus frequency.

  15. PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems

    NASA Technical Reports Server (NTRS)

    Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.

    2003-01-01

    A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.

  16. Ionospheric total-electron-content estimation for single-frequency Global-positioning-system receivers

    SciTech Connect

    Smith, C.A.

    1987-01-01

    The ionosphere delays transmissions from the Global Positioning System (GPS), as well as those from other satellite systems. At the GPS frequencies (L-Band), this delay is directly proportional to the total ionospheric electron content (TEC) along the line-of-sight to the satellite. Classified receivers have access to 2 frequencies to allow them to measure this delay through the difference in the ionospheric effect at the 2 frequencies, but commercial, single-frequency receivers have had no direct method for estimating the ionospheric delay; they have had to rely on a TEC prediction. Two methods are described for single-frequency GPS receivers to estimate the ionospheric TEC directly. These methods take advantage of the dispersive nature of the ionosphere at L-Band frequencies, which causes a phase advance of the carrier that is opposite to the group delay of the GPS code and data.

  17. Automated frequency domain system identification of a large space structure

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Bayard, D. S.; Hadaegh, F. Y.; Mettler, E.; Milman, M. H.

    1989-01-01

    This paper presents the development and experimental results of an automated on-orbit system identification method for large flexible spacecraft that yields estimated quantities to support on-line design and tuning of robust high performance control systems. The procedure consists of applying an input to the plant, obtaining an output, and then conducting nonparametric identification to yield the spectral estimate of the system transfer function. A parametric model is determined by curve fitting the spectral estimate to a rational transfer function. The identification method has been demonstrated experimentally on the Large Spacecraft Control Laboratory in JPL.

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

    NASA Astrophysics Data System (ADS)

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

    1984-11-01

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

  19. Noise-Induced Phase Locking and Frequency Mixing in an Optical Bistable System with Delayed Feedback

    NASA Astrophysics Data System (ADS)

    Misono, Masatoshi; Miyakawa, Kenji

    2011-11-01

    The interplay between stochastic resonance (SR) and coherence resonance (CR) is experimentally studied in an optical bistable system with a time-delayed feedback loop. We demonstrate that the phase of the noise-induced motion is locked to that of the periodic input when the ratio of their frequencies is a simple rational number. We also demonstrate that the interplay between SR and CR generates frequency-mixed modes, and that the efficiency of frequency mixing is enhanced by the optimum noise.

  20. Low-latency digital frequency synthesizer using the residue number system

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.

    1993-01-01

    A low-latency frequency synthesizer using the Direct Digital Synthesis (DDS) technique has been designed. Called the Residue Assisted Frequency Synthesizer (RAFS), it exhibits frequency switching times which are reduced by more than 50 percent below previously published designs. The switching speed advantage is made possible by the use of the Residue Number System, which allows the pipeline lengths in the Phase Accumulator and other circuitry to be reduced significantly.

  1. Two-frequency information recording in a three-level system using stimulated photon echo

    SciTech Connect

    Garnaeva, G I; Nefediev, L A; Akhmedshina, E N; Garnaev, R N

    2015-07-31

    The process of recording and reproducing information in a three-level system using stimulated photon echo is studied as a function of the amount of information embedded in the first and second two-frequency object laser pulses. It is shown that two-frequency information recording leads to an increase in the power of the stimulated photon echo response on one frequency transition and to its reduction on the other. (laser applications and other topics in quantum electronics)

  2. Very High Frequency Monitoring System for Engine Gearbox and Generator Health Management (Postprint)

    DTIC Science & Technology

    2007-09-18

    Application of Health and Usage Monitoring System (HUMS) Technologies to Wind Turbine Drive Trains,” WindPower 2005, Denver, CO, May 15-18, 2005...AFRL-RZ-WP-TP-2008-2043 VERY HIGH FREQUENCY MONITORING SYSTEM FOR ENGINE GEARBOX AND GENERATOR HEALTH MANAGEMENT (POSTPRINT) Matthew J...2649 5b. GRANT NUMBER 4. TITLE AND SUBTITLE VERY HIGH FREQUENCY MONITORING SYSTEM FOR ENGINE GEARBOX AND GENERATOR HEALTH MANAGEMENT (POSTPRINT

  3. Characterization of an intraluminal differential frequency-domain photoacoustics system

    NASA Astrophysics Data System (ADS)

    Lashkari, Bahman; Son, Jungik; Liang, Simon; Castelino, Robin; Foster, F. Stuart; Courtney, Brian; Mandelis, Andreas

    2016-03-01

    Cardiovascular related diseases are ranked as the second highest cause of death in Canada. Among the most important cardiovascular diseases is atherosclerosis. Current methods of diagnosis of atherosclerosis consist of angiography, intravascular ultrasound (IVUS) and optical coherence tomography (OCT). None of these methods possesses adequate sensitivity, as the ideal technique should be capable of both depth profiling, as well as functional imaging. An alternative technique is photoacoustics (PA) which can perform deep imaging and spectroscopy. The presented study explores the application of wavelength-modulated differential photoacoustic radar (WM-DPAR) for characterizing arterial vessels. The wavelength-modulated differential photoacoustic technique was shown to be able to substantially increase the dynamic range and sensitivity of hemoglobin oxygenation level detection. In this work the differential PA technique was used with a very high frequency modulation range. To perform spectroscopic PA imaging, at least two wavelengths are required. The selected wavelengths for this work are 1210 nm and 980 nm. 1210 nm corresponds to the maximum optical absorption coefficient of cholesterol and cholesteryl esters which are the main constituents of plaques. Since water, elastin and collagen also have high absorption coefficients at 1210 nm, this wavelength alone cannot provide very high sensitivity and specificity. The additional wavelength, 980 nm corresponds to high absorption coefficient of those constituents of healthy artery tissue. The simultaneous application of the abovementioned wavelengths can provide higher sensitivity and improved specificity in detecting lipids in the arterial vessels.

  4. Compact Superconducting Radio-frequency Accelerators and Innovative RF Systems

    SciTech Connect

    Kephart, Robert; Chattopadhyay, Swaapan; Milton, Stephen

    2015-04-10

    We will present several new technical and design breakthroughs that enable the creation of a new class of compact linear electron accelerators for industrial purposes. Use of Superconducting Radio-Frequency (SRF) cavities allow accelerators less than 1.5 M in length to create electron beams beyond 10 MeV and with average beam powers measured in 10’s of KW. These machines can have the capability to vary the output energy dynamically to produce brehmstrahlung x-rays of varying spectral coverage for applications such as rapid scanning of moving cargo for security purposes. Such compact accelerators will also be cost effective for many existing and new industrial applications. Examples include radiation crosslinking of plastics and rubbers, creation of pure materials with surface properties radically altered from the bulk, modification of bulk or surface optical properties of materials, sterilization of medical instruments animal solid or liquid waste, and destruction of organic compounds in industrial waste water effluents. Small enough to be located on a mobile platform, such accelerators will enable new remediation methods for chemical and biological spills and/or in-situ crosslinking of materials. We will describe one current design under development at Fermilab including plans for prototype and value-engineering to reduce costs. We will also describe development of new nano-structured field-emitter arrays as sources of electrons, new methods for fabricating and cooling superconducting RF cavities, and a new novel RF power source based on magnetrons with full phase and amplitude control.

  5. On the Natural Frequency of Tidal Current Power Systems - A Discussion of Sea Testing

    SciTech Connect

    Li, Ye; Yi, Jin-Hak; Song, Huimin; Wang, Qi; Yang, Zhaoqing; Kelley, Neil D.; Lee, Kwang-Soo

    2014-07-14

    In order to study its wet natural frequency (in water) and dry frequency (in air), we conducted a two-year measurement campaign by deploying a full-scale prototype tidal current turbine system. A theoretical model is validated, and reveals the measured wet natural frequency of the device could be 54.6% of the dry frequency. Among short-term physics, inflow turbulence is important in the excitation of system resonances that can lead to fatigue damage and system failure. Among long-term physics, the wet natural frequency is highly dependent on tidal constituents, the semi-diurnal tides (M2 and S2) and diurnal tides (K1 and O1).

  6. Low-frequency vibration measurement based on camera-projector system

    NASA Astrophysics Data System (ADS)

    Lyu, Chengang; Liu, Yuxiang; Gao, Shuang; Bao, Zhiqiang; Chang, Yuqing; Gao, Jiale; Yang, Jiachen; Jin, Jie

    2017-09-01

    A low-frequency vibration measurement based on a camera-projector system is proposed and verified by experiment at several hertz. A CCD camera gathered deformed fringes modulated by a vibrating trumpet at a constant sampling rate. Information on amplitude and frequency are contained in a series of observed images. The height value of each pixel point in the image can be restored by using Fourier transform profilometry. Connecting the height value of every sampling frame into a motion trajectory, the frequency and amplitude of the vibrating object can be obtained from the trajectory curve. The experiment restored the vibration process of a trumpet in half a cycle while the vibrating frequency was 3 Hz. Subsequently, the measurement of different frequencies and different amplitudes are comparatively studied. The results show that slight vibration at 35 µm and above can be detected by the system, which confirms the feasibility of the proposed system in the field of industrial vibration measurement.

  7. A theory of the visual system biology underlying development of spatial frequency lateralization.

    PubMed

    Howard, Mary F; Reggia, James A

    2007-07-01

    The spatial frequency hypothesis contends that performance differences between the hemispheres on various visuospatial tasks are attributable to lateralized processing of the spatial frequency content of visual stimuli. Hellige has proposed that such lateralization could arise during infant development from the earlier maturation of the right hemisphere combined with the increasing sensitivity of the visual system to high spatial frequencies. This proposal is intuitively appealing but lacks an explicit theory with respect to the underlying visual system biology. In this paper, we develop such a theory based on knowledge of visual system processing and development. We then translate our theory into a computational model that serves as the basis for a series of development simulations. We find that the simulations produce spatial frequency lateralization effects consistent with those observed empirically. We relate the nature of the neural asymmetry implied by our theory to empirical findings on visual pathway bias and the relative spatial frequency lateralization effect.

  8. Determining the linear combination of the fundamental frequencies in N-body systems

    NASA Astrophysics Data System (ADS)

    Süli, Á.

    In this article the linear combinations of fundamental frequencies of a simplified Solar System were determined. This model consists of Venus, Earth, Mars, Jupiter and Saturn with their actual orbital elements. The frequencies present in the system were derived on one hand using the results of a numerical integration via an appropriate frequency analysis and on the other hand via the analytical Laplace-Lagrange theory. These frequencies were compared to already existing results; it turned out that this model is a very good representation of the whole Solar System concerning the frequencies involved. The amplitudes of the planets in the two different models were also compared. The periods, the corresponding linear combinations and, amplitudes of the five planets are presented in tables.

  9. The Sensitivity Analysis of Inherent Frequency of Roll Mill’s Main Drive System

    NASA Astrophysics Data System (ADS)

    Hou, Dongxiao

    2017-07-01

    In order to avoid the beat vibration of rolling mill, taking F1 rolling mill of 1780 tandem mill as an example, a twelve DOF branched torsional vibration model of main drive system of F1 rolling mill was constructed. Then the inherent frequency of the rolling mill and the corresponding vibration modes of every inherent frequency were calculated. Meanwhile, the sensitivity of first and second inherent frequency with the change of equivalent rotational inertias and torsional stiffness of rolling mill were analyzed, and the most sensitive parameters which influence on first and second inherent frequency were found out. The result shows that the equivalent inertias of upper and lower work rolls and equivalent stiffness of upper and lower joint shaft of drive system were most sensitive parameters, which are easier to change first and second inherent frequency of drive system. The research will provide theory reference for adopting proper mechanical parameters in equipment design.

  10. A study of amplitude information-frequency characteristics for underwater active electrolocation system.

    PubMed

    Peng, Jiegang

    2015-11-04

    Weakly electric fish sense their surroundings in complete darkness by their active electrolocation system. For biologists, the active electrolocation system has been investigated for near 60 years. And for engineers, bio-inspired active electrolocation sensor has been investigated for about 20 years. But how the amplitude information response will be affected by frequencies of detecting electric fields in the active electrolocation system was rarely investigated. In this paper, an electrolocation experiment system has been built. The amplitude information-frequency characteristics (AIFC) of the electrolocation system for sinusoidal electric fields of varying frequencies have been investigated. We find that AIFC of the electrolocation system have relevance to the material properties and geometric features of the probed object and conductivity of surrounding water. Detect frequency dead zone (DFDZ) and frequency inflection point (FIP) of AIFC for the electrolocation system were found. The analysis model of the electrolocation system has been investigated for many years, but DFDZ and FIP of AIFC can be difficult to explain by those models. In order to explain those AIFC phenomena for the electrolocation system, a simple relaxation model based on Cole-Cole model which is not only a mathematical explanation but it is a physical one for the electrolocation system was advanced. We also advance a hypothesis for physical mechanism of weakly electrical fish electrolocation system. It may have reference value for physical mechanism of weakly electrical fish active electrolocation system.

  11. Coda Q and its Frequency Dependence in the Eastern Himalayan and Indo-Burman Plate Boundary Systems

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Kumar, A.

    2015-12-01

    We use broadband waveform data for 305 local earthquakes from the Eastern Himalayan and Indo-Burman plate boundary systems, to model the seismic attenuation in NE India. We measure the decay in amplitude of coda waves at discreet frequencies (between 1 and 12Hz) to evaluate the quality factor (Qc) as a function of frequency. We combine these measurements to evaluate the frequency dependence of Qc of the form Qc(f)=Qof η, where Qo is the quality factor at 1Hz and η is the frequency dependence. Computed Qo values range from 80-360 and η ranges from 0.85-1.45. To study the lateral variation in Qo and η, we regionalise the Qc by combining all source-receiver measurements using a back-projection algorithm. For a single back scatter model, the coda waves sample an elliptical area with the epicenter and receiver at the two foci. We parameterize the region using square grids. The algorithm calculates the overlap in area and distributes Qc in the sampled grids using the average Qc as the boundary value. This is done in an iterative manner, by minimising the misfit between the observed and computed Qc within each grid. This process is repeated for all frequencies and η is computed for each grid by combining Qc for all frequencies. Our results reveal strong variation in Qo and η across NE India. The highest Qo are in the Bengal Basin (210-280) and the Indo-Burman subduction zone (300-360). The Shillong Plateau and Mikir Hills have intermediate Qo (~160) and the lowest Qo (~80) is observed in the Naga fold thrust belt. This variation in Qo demarcates the boundary between the continental crust beneath the Shillong Plateau and Mikir Hills and the transitional to oceanic crust beneath the Bengal Basin and Indo-Burman subduction zone. Thick pile of sedimentary strata in the Naga fold thrust belt results in the low Qo. Frequency dependence (η) of Qc across NE India is observed to be very high, with regions of high Qo being associated with relatively higher η.

  12. Radio frequency science considerations. [technology utilization of telecommunications system

    NASA Technical Reports Server (NTRS)

    Croft, T. A.

    1974-01-01

    Use of the 400 MHz telecommunications system to obtain scientific information, to provide backup information for the experiments flown, and to obtain measurements which aid in designing future probes is considered. Recommended objectives of such a program are summarized and include: measure 400 MHz amplitude to determine adsorption and perhaps scintillation (if data rate permits); measure noise strength near 400 MHz to reexamine 400 MHz choice and to observe thermal, cosmic, and local synchrotron noise trends; probe VSWR sensing to monitor integrity of system, icing, and possible plasma effects; after the probe is finished, have the bus radio occultation in the same region where the probe fell to evaluate the occultation.

  13. General Conditions for Proximity-Induced Odd-Frequency Superconductivity in Two-Dimensional Electronic Systems.

    PubMed

    Triola, Christopher; Badiane, Driss M; Balatsky, Alexander V; Rossi, E

    2016-06-24

    We obtain the general conditions for the emergence of odd-frequency superconducting pairing in a two-dimensional (2D) electronic system proximity coupled to a superconductor, making minimal assumptions about both the 2D system and the superconductor. Using our general results we show that a simple heterostructure formed by a monolayer of a group VI transition metal dichalcogenide, such as molybdenum disulfide, and an s-wave superconductor with Rashba spin-orbit coupling exhibits odd-frequency superconducting pairing. Our results allow the identification of a new class of systems among van der Waals heterostructures in which odd-frequency superconductivity should be present.

  14. Model-based frequency response characterization of a digital-image analysis system for epifluorescence microscopy

    NASA Technical Reports Server (NTRS)

    Hazra, Rajeeb; Viles, Charles L.; Park, Stephen K.; Reichenbach, Stephen E.; Sieracki, Michael E.

    1992-01-01

    Consideration is given to a model-based method for estimating the spatial frequency response of a digital-imaging system (e.g., a CCD camera) that is modeled as a linear, shift-invariant image acquisition subsystem that is cascaded with a linear, shift-variant sampling subsystem. The method characterizes the 2D frequency response of the image acquisition subsystem to beyond the Nyquist frequency by accounting explicitly for insufficient sampling and the sample-scene phase. Results for simulated systems and a real CCD-based epifluorescence microscopy system are presented to demonstrate the accuracy of the method.

  15. Regional evaluation of the hydrogeologic framework, hydraulic properties, and chemical characteristics of the intermediate aquifer system underlying southern west-central Florida

    USGS Publications Warehouse

    Knochenmus, Lari A.

    2006-01-01

    Three major aquifer systems-the surficial aquifer system, the intermediate aquifer system, and the Floridan aquifer system-are recognized in the approximately 5,100-square-mile southern west-central Florida study area. The principal source of freshwater for all uses is ground water supplied from the three aquifer systems. Ground water from the intermediate aquifer system is considered only moderately abundant compared to the Upper Floridan aquifer, but it is an important source of water where the Upper Floridan aquifer contains water too mineralized for most uses. In the study area, the potential ground-water resources of the intermediate aquifer system were evaluated by regionally assessing the vertical and lateral distribution of hydrogeologic, hydraulic, and chemical characteristics. Although the intermediate aquifer system is considered a single entity, it is composed of multiple water-bearing zones separated by confining units. Deposition of a complex assemblage of carbonate and siliciclastic sediments during the late Oligocene to early Pliocene time resulted in discontinuities that are reflected in transitional and abrupt contacts between facies. Discontinuous facies produce water-bearing zones that may be locally well-connected or culminate abruptly. Changes in the depositional environment created the multilayered intermediate aquifer system that contains as many as three zones of enhanced water-bearing capacity. The water-bearing zones consist of indurated limestone and dolostone and in some places unindurated sand, gravel, and shell beds, and these zones are designated, in descending order, as Zone 1, Zone 2, and Zone 3. Zone 1 is thinnest (<80 feet thick) and is limited to <20 percent (southern part) of the study area. Zone 2, the only regionally extensive zone, is characterized by moderately low permeability. Zone 3 is found in about 50 percent of the study area, has the highest transmissivities, and generally is in good hydraulic connection with the

  16. Synthesis of vibration systems, having group symmetry or quasi-symmetry, according to the frequency spectrum

    NASA Technical Reports Server (NTRS)

    Andryushkevichyus, A. I.; Ragulskis, K. M.

    1973-01-01

    Torsional vibration systems, with finite numbers of degrees of freedom are investigated. In designing such systems, it is important to select parameters, so that the frequency spectrum of the natural vibrations is beyond the limits of the resonance danger region. In the case when the system has a large number of degrees of freedom, calculation of its natural frequencies, as well as tuning out the resonance danger zones is laborious. When the system being investigated has one group symmetry or another, solution of the problem mentioned above is facilitated, as a consequence of breaking down the frequency equations into several, which are smaller in size. An algorithm is given for tuning out the natural frequency spectrum from the forbidden region, by means of varying the rigidity of systems having group symmetries or group quasi-symmetries.

  17. Unified tensor model for space-frequency spreading-multiplexing (SFSM) MIMO communication systems

    NASA Astrophysics Data System (ADS)

    de Almeida, André LF; Favier, Gérard

    2013-12-01

    This paper presents a unified tensor model for space-frequency spreading-multiplexing (SFSM) multiple-input multiple-output (MIMO) wireless communication systems that combine space- and frequency-domain spreadings, followed by a space-frequency multiplexing. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades and provides space and frequency diversities, while orthogonal space-frequency multiplexing enables multi-stream transmission. We adopt a tensor-based formulation for the proposed SFSM MIMO system that incorporates space, frequency, time, and code dimensions by means of the parallel factor model. The developed SFSM tensor model unifies the tensorial formulation of some existing multiple-access/multicarrier MIMO signaling schemes as special cases, while revealing interesting tradeoffs due to combined space, frequency, and time diversities which are of practical relevance for joint symbol-channel-code estimation. The performance of the proposed SFSM MIMO system using either a zero forcing receiver or a semi-blind tensor-based receiver is illustrated by means of computer simulation results under realistic channel and system parameters.

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

    NASA Astrophysics Data System (ADS)

    Soldatov, Andrey V.

    2016-09-01

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

  19. RFQ (radio-frequency quadrupole) accelerator tuning system

    DOEpatents

    Bolie, V.W.

    1988-04-12

    A cooling system is provided for maintaining a preselected operating temperature in a device, which may be an RFQ accelerator, having a variable heat removal requirement, by circulating a cooling fluid through a cooling system remote from the device. Internal sensors in the device enable an estimated error signal to be generated from parameters which are indicative of the heat removal requirement from the device. Sensors are provided at predetermined locations in the cooling system for outputting operational temperature signals. Analog and digital computers define a control signal functionally related to the temperature signals and the estimated error signal, where the control signal is defined effective to return the device to the preselected operating temperature in a stable manner. The cooling system includes a first heat sink responsive to a first portion of the control signal to remove heat from a major portion of the circulating fluid. A second heat sink is responsive to a second portion of the control to remove heat from a minor portion of the circulating fluid. The cooled major and minor portions of the circulating fluid are mixed in responsive to a mixing portion of the control signal, which is effective to proportion the major and minor portions of the circulating fluid to establish a mixed fluid temperature which is effective to define the preselected operating temperature for the remote device. 3 figs., 2 tabs.

  20. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    NASA Technical Reports Server (NTRS)

    Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

    2017-01-01

    A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

  1. Nonfragile filtering for discrete-time linear systems in finite-frequency domain

    NASA Astrophysics Data System (ADS)

    Ding, Da-Wei; Li, Xiaoli; Wang, Youyi

    2013-04-01

    This article investigates the problem of nonfragile filter design for discrete-time linear systems subject to noises with known frequency ranges. Additive interval uncertainty reflecting imprecision in filter implementation is considered. By the aid of generalised KYP lemma, both deterministic and randomised filtering algorithms are proposed to deal with noises in low-, middle- and high-frequency domain, respectively. The proposed nonfragile finite-frequency filters can get a better noise attenuation performance when frequency ranges of noises are known beforehand. An example about F-18 aircraft model is given to illustrate the effectiveness of the proposed algorithms.

  2. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    NASA Technical Reports Server (NTRS)

    Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

    2014-01-01

    A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

  3. Extension of the system constants database for open-tubular columns: system maps at low and intermediate temperatures for four new columns.

    PubMed

    Atapattu, Sanka N; Eggers, Kimberly; Poole, Colin F; Kiridena, Waruna; Koziol, Wladyslaw W

    2009-03-06

    The solvation parameter model is used to characterize the separation properties of four open-tubular columns for gas chromatography at low and intermediate column temperatures covering the range 60-240 degrees C. Solute descriptors for compounds suitable for characterizing columns over the intermediate temperature range are optimized using an iterative procedure. These compounds, and those previously recommended for the lower temperature range, are used to provide system constant maps for Rxi-5Sil MS, Rxi-17, Rtx-TNT and Rtx-TNT2 columns suitable for merging with a system constants database with entries for more than 50 columns. The Rxi-5Sil MS column is shown to have separation properties similar to the silphenylene-dimethylsiloxane copolymer stationary phase (DB-5ms) but these two columns are not selectivity equivalent. The Rxi-17 column has similar separation properties to the Rxi-50 column but is not selectivity equivalent to it. Rxi-17 is a poly(dimethyldiphenylsiloxane) stationary phase containing 50% diphenylsiloxane monomer and Rxi-50 a poly(methylphenylsiloxane) stationary phase with the same nominal composition but a different monomer structure. The difference in monomer structure results in only small changes in selectivity, and for all but the most demanding separations, the columns are interchangeable. The application-specific column (energetic materials) Rtx-TNT is shown to be selectivity equivalent to columns coated with the poly(dimethyldiphenylsiloxane) stationary phases containing 5% diphenylsiloxane monomer. The Rtx-TNT2 column is selectivity equivalent to the proprietary Rtx-OPPesticides column. Rtx-OPPesticides is a low bleed stationary phase, possibly based on silarylene-siloxane chemistry, with a composition designed to mimic the separation properties of the poly(dimethylmethyltrifluoropropylsiloxane) stationary phases containing 35% methyltrifluoropropylsiloxane monomer. Selectivity equivalence of columns is determined by the statistical

  4. Development and approach to low-frequency microgravity isolation systems

    NASA Technical Reports Server (NTRS)

    Grodsinsky, Carlos M.

    1990-01-01

    The low-gravity environment provided by space flight has afforded the science community a unique arena for the study of fundamental and technological sciences. However, the dynamic environment observed on space shuttle flights and predicted for Space Station Freedom has complicated the analysis of prior microgravity experiments and prompted concern for the viability of proposed space experiments requiring long-term, low-gravity environments. Thus, isolation systems capable of providing significant improvements to this random environment are being developed. The design constraints imposed by acceleration-sensitive, microgravity experiment payloads in the unique environment of space and a theoretical background for active isolation are discussed. A design is presented for a six-degree-of-freedom, active, inertial isolation system based on the baseline relative and inertial isolation techniques described.

  5. High Temperature VSCF (Variable Speed Constant Frequency) Generator System

    DTIC Science & Technology

    1989-04-01

    be’ing developed to reduce size and weight on all production programs. Monsanto OS-124 oil properties were used for heat transfer and fluid flow...is an important design consideration for higher temperature operation. Use of a lower expansion and stronger composite material such as cast AZ91 mg...systems were investigated. Figures 5 through 7 give a comparison of the tensile properties of composites with the properties of an unreinforced alloy. It

  6. Robust low-frequency spread-spectrum navigation system

    DOEpatents

    Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

    2009-12-01

    Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

  7. Robust low-frequency spread-spectrum navigation system

    DOEpatents

    Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

    2011-01-25

    Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

  8. Robust low-frequency spread-spectrum navigation system

    DOEpatents

    Smith, Stephen F; Moore, James A

    2012-10-30

    Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

  9. Robust low-frequency spread-spectrum navigation system

    DOEpatents

    Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

    2012-01-03

    Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

  10. SPECTRON, a neutron noise measurement system in frequency domain.

    PubMed

    de Izarra, G; Jammes, C; Geslot, B; Di Salvo, J; Destouches, C

    2015-11-01

    This paper is dedicated to the presentation and validation of SPECTRON, a novel neutron noise measurement system developed at CEA Cadarache. The device is designed for the measurement of the β(eff) parameter (effective fraction of delayed neutrons) of experimental nuclear reactors using the Cohn-α method. An integrated electronic system is used to record the current from fission chambers. Spectra computed from measurement data are processed by a dedicated software in order to estimate the reactor transfer function and then the effective fraction of delayed neutrons as well as the prompt neutron generation time. After a review of the pile noise measurement method in current mode, the SPECTRON architecture is presented. Then, the validation procedure is described and experimental results are shown, supporting the proper functioning of this new measurement system. It is shown that every technical requirement needed for correct measurement of neutron noise is fulfilled. Measurements performed at MINERVE and EOLE, two experimental nuclear reactors at CEA Cadarache, in real conditions allowed us to validate SPECTRON.

  11. System Control Applications of Low-Power Radio Frequency Devices

    NASA Astrophysics Data System (ADS)

    van Rensburg, Roger

    2017-09-01

    This paper conceptualizes a low-power wireless sensor network design for application employment to reduce theft of portable computer devices used in educational institutions today. The aim of this study is to design and develop a reliable and robust wireless network that can eradicate accessibility of a device’s human interface. An embedded system supplied by an energy harvesting source, installed on the portable computer device, may represent one of multiple slave nodes which request regular updates from a standalone master station. A portable computer device which is operated in an undesignated area or in a field perimeter where master to slave communication is restricted, indicating a possible theft scenario, will initiate a shutdown of its operating system and render the device unusable. Consequently, an algorithm in the device firmware may ensure the necessary steps are executed to track the device, irrespective whether the device is enabled. Design outcomes thus far indicate that a wireless network using low-power embedded hardware, is feasible for anti-theft applications. By incorporating one of the latest Bluetooth low-energy, ANT+, ZigBee or Thread wireless technologies, an anti-theft system may be implemented that has the potential to reduce major portable computer device theft in institutions of digitized learning.

  12. SPECTRON, a neutron noise measurement system in frequency domain

    SciTech Connect

    Izarra, G. de; Jammes, C. Destouches, C.; Geslot, B.; Di Salvo, J.

    2015-11-15

    This paper is dedicated to the presentation and validation of SPECTRON, a novel neutron noise measurement system developed at CEA Cadarache. The device is designed for the measurement of the β{sub eff} parameter (effective fraction of delayed neutrons) of experimental nuclear reactors using the Cohn-α method. An integrated electronic system is used to record the current from fission chambers. Spectra computed from measurement data are processed by a dedicated software in order to estimate the reactor transfer function and then the effective fraction of delayed neutrons as well as the prompt neutron generation time. After a review of the pile noise measurement method in current mode, the SPECTRON architecture is presented. Then, the validation procedure is described and experimental results are shown, supporting the proper functioning of this new measurement system. It is shown that every technical requirement needed for correct measurement of neutron noise is fulfilled. Measurements performed at MINERVE and EOLE, two experimental nuclear reactors at CEA Cadarache, in real conditions allowed us to validate SPECTRON.

  13. A novel dual-frequency loading system for studying mechanobiology of load-bearing tissue.

    PubMed

    Zhang, Chunqiu; Qiu, Lulu; Gao, Lilan; Guan, Yinjie; Xu, Qiang; Zhang, Xizheng; Chen, Qian

    2016-12-01

    In mechanobiological research, an appropriate loading system is an essential tool to mimic mechanical signals in a native environment. To achieve this goal, we have developed a novel loading system capable of applying dual-frequency loading including both a low-frequency high-amplitude loading and a high-frequency low-amplitude loading, according to the mechanical conditions experienced by bone and articular cartilage tissues. The low-frequency high-amplitude loading embodies the main force from muscular contractions and/or reaction forces while the high-frequency low-amplitude loading represents an assistant force from small muscles, ligaments and/or other tissue in order to maintain body posture during human activities. Therefore, such dual frequency loading system may reflect the natural characteristics of complex mechanical load on bone or articular cartilage than the single frequency loading often applied during current mechanobiological experiments. The dual-frequency loading system is validated by experimental tests using precision miniature plane-mirror interferometers. The dual-frequency loading results in significantly more solute transport in articular cartilage than that of the low-frequency high-amplitude loading regiment alone, as determined by quantitative fluorescence microscopy of tracer distribution in articular cartilage. Thus, the loading system can provide a new method to mimic mechanical environment in bone and cartilage, thereby revealing the in vivo mechanisms of mechanosensation, mechanotransduction and mass-transport, and improving mechanical conditioning of cartilage and/or bone constructs for tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Participation and coordination in Dutch health care policy-making. A network analysis of the system of intermediate organizations in Dutch health care.

    PubMed

    Lamping, Antonie J; Raab, Jörg; Kenis, Patrick

    2013-06-01

    This study explores the system of intermediate organizations in Dutch health care as the crucial system to understand health care policy-making in the Netherlands. We argue that the Dutch health care system can be understood as a system consisting of distinct but inter-related policy domains. In this study, we analyze four such policy domains: Finances, quality of care, manpower planning and pharmaceuticals. With the help of network analytic techniques, we describe how this highly differentiated system of >200 intermediate organizations is structured and coordinated and what (policy) consequences can be observed with regard to its particular structure and coordination mechanisms. We further analyze the extent to which this system of intermediate organizations enables participation of stakeholders in policy-making using network visualization tools. The results indicate that coordination between the different policy domains within the health care sector takes place not as one would expect through governmental agencies, but through representative organizations such as the representative organizations of the (general) hospitals, the health care consumers and the employers' association. We further conclude that the system allows as well as denies a large number of potential participants access to the policy-making process. As a consequence, the representation of interests is not necessarily balanced, which in turn affects health care policy. We find that the interests of the Dutch health care consumers are well accommodated with the national umbrella organization NPCF in the lead. However, this is no safeguard for the overall community values of good health care since, for example, the interests of the public health sector are likely to be marginalized.

  15. Analysis of frequency domain frame detection and synchronization in OQAM-OFDM systems

    NASA Astrophysics Data System (ADS)

    Thein, Christoph; Schellmann, Malte; Peissig, Jürgen

    2014-12-01

    For future communication systems, filter bank multicarrier schemes offer the flexibility to increase spectrum utilization in heterogeneous wireless environments by good separation of signals in the frequency domain. To fully exploit this property for frame detection and synchronization, the advantage of the filter bank should be taken at the receiver side. In this work, the concept of frequency domain processing for frame detection and synchronization is analyzed and a suitable preamble design as well as corresponding estimation algorithms is discussed. The theoretical performance of the detection and estimation schemes is derived and compared with simulation-based assessments. The results show that, even though the frequency domain algorithms are sensitive to carrier frequency offsets, satisfactory frame detection and synchronization can be achieved in the frequency domain. In comparison to time domain synchronization methods, the computational complexity increases; however, enhanced robustness in shared spectrum access scenarios is gained in case the described frequency domain approach is utilized.

  16. Frequency response design of uncertain systems using performance indices and meta-models

    NASA Astrophysics Data System (ADS)

    Savage, Gordon J.; Son, Young Kap

    2013-12-01

    Systems that are operated near their resonance frequencies experience vibrations that can lead to impaired performance, overstressing, fatigue fracture and adverse human reactions. Frequency response (FR) analysis can be invoked to mitigate the effects. When components of a system are described by random variables, modal frequencies and modal shapes, or, amplitudes and phases, are also random variables and the frequency response (FR) design of the system becomes more complex since it requires the solution of a frequency-variant probability problem. This paper presents a methodology to provide the frequency response design of uncertain systems using a transfer function approach. The methodology is found to be robust, expandable and flexible and can be applied to multi-disciplinary systems with n-dof and multiple design constraints. The novelty of the approach is the creation of a frequency-invariant probability problem through: (a) the discretization of the frequency band of interest into multiple contiguous point frequencies, (b) the introduction of new performance indices that measure the probability of success over the entire frequency band, and (c) the introduction of explicit meta-models to provide sufficiently fast probability evaluations through Monte Carlo simulation. The key to the performance indices are limit-state functions formed at all discrete, contiguous, frequencies. Each limit-state function establishes a conformance region in terms of the random design variables. The probabilities of the conformance regions are correctly combined to provide a single series-system index to be maximized by adjusting distribution parameters. The simple explicit meta-model is based on Kriging and performance measures at arbitrary design sets are efficiently calculated. Error analysis suggests ways to predict and control the errors with regards to meta-model fitting and probability calculations and so the method appears sufficiently accurate for engineering

  17. Control system architecture of QUIJOTE multi-frequency instrument

    NASA Astrophysics Data System (ADS)

    Gómez-Reñasco, María. F.; Aguiar, Marta; Herreros, José Miguel; Hoyland, Roger J.; Sánchez de la Rosa, Vicente; Vega-Moreno, Afrodisio; Viera-Curbelo, Teodora; Génova-Santos, Ricardo; López-Caraballo, Carlos; Rebolo, Rafael; Rubiño-Martín, Jose Alberto

    2012-09-01

    The QUIJOTE-CMB experiment has been described in previous publications. Here we describe the architecture of the control system, hardware and software, of the QUIJOTE I instrument (MFI). It is a multi-channel instrument with five separate polarimeters: two of which operate at 10-14 GHz, two of which operate at 16-20 GHz, and a central polarimeter at 26-36 GHz. Each polarimeter can rotate at a speed of up to 1 Hz and also can move to discrete angular positions which allow the linear polar parameters Q, U and I to be derived. The instrument is installed in an alt-azimuth telescope which implements several operational modes: movement around the azimuth axis at a constant velocity while the elevation axis is held at a fixed elevation; tracking of a sky object; and raster of a rectangular area both in horizontal and sky coordinates. The control system of both, telescope and instrument, is based in the following technologies: an LXI-VXI bus is used for the signal acquisition system; an EtherCAT bus implements software PLCs developed in TwinCAT to perform the movement of the 5 polarimeters and the 2 axes of the telescope. Science signal, angular positions of the 5 polarimeters and telescope coordinates are sampled at up to 4000 Hz. All these data are correlated by a time stamp obtained from an external GPS clock implementing the Precise Time Protocol-1588 which provides synchronization to less than 1 microsecond. The control software also acquires housekeeping (HK) from the different subsystems. LabVIEW implements the instrument user interface.

  18. Development of the circuit system in high frequency satellite laser ranging equipment based on FPGA

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Fan, Chunbo; Li, Zhenwei; Zhao, You

    2008-12-01

    High frequency, as well as automation and day light ranging, is a signify feature of new generation Satellite Laser Ranging (SLR) systems. In spite of increase the quantity of observation data, the high frequency SLR can also significantly improve the SP and NP precision. These trends of SLR technology lead to new requirement of control circuit. In this paper, an implementation of control circuit in single FPGA chip was present. SOPC (system on programmable chip) system was proposed to solve these problems. To realize the system, a control circuit custom component was designed and simulated by us. Then, the component was integrated into a SOPC system. Cooperated with software, the circuit has the ability to control the SLR system running at high frequency. Finally, the system was simulated in the Quartus software and NIOS IDE provided by Altera and implemented in an Altera EP1S10 development kit.

  19. Portable High-Frequency Data-Acquisition System

    NASA Technical Reports Server (NTRS)

    Mustain, Roy W.

    1990-01-01

    Compact unit made of readily available solid-state components. Proposed system for acquisition of rapidly changing data self-contained and portable. Conceived for monitoring such aerodynamic effects as flutter, vibration, shock, sound, and pressure. Offers precise and fast acquisition of data and large data-storage capacity: has maximum sampling rate of 125 kHz, access time of 15 ns, and 1-million-bit memory. Measures time with "smart" (microprocessor-controlled) watch that maintains calendar time for more than 10 years without external power. Provides standby power from "smart" battery furnishing up to 1 ampere-hour of charge if power from main batteries lost.

  20. Effect of coherence and polarization on frequency resolution in optical Fourier transforming system.

    PubMed

    Ostrovsky, Andrey S; Olvera-Santamaría, Miguel Á; Romero-Soría, Paulo C

    2011-12-01

    Using an example of vector Gaussian Schell-model beam, we demonstrate and analyze the dependence of the spatial frequency resolution in optical Fourier transforming system on the intrinsic coherence-polarization structure of illumination.

  1. Wavelength Modulation Absorption Spectroscopy Using a Frequency-Quadruped Current-Modulated System

    NASA Astrophysics Data System (ADS)

    Shao, Jie; Sun, Hui-Juan; Wang, Hui; Zhou, Wei-Dong; Wu, Gen-Zhu

    2010-05-01

    A wavelength modulation absorption spectrometry (WMAS) with a frequency-quadruped system is demonstrated. The frequency-quadruped system consists of a two-frequency doubled external enhancement cavity with KNO3 and BBO crystals, and a current-modulated 906-nm single mode external cavity diode laser (ECDL), which generates the tunable wavelength modulated radiation at 226.7 nm used to detect the NO absorption line that belongs to the combined Q22(10.5) and QR12(10.5) lines of 7(0, 0) band within the A2Σ+ - X2II electronic transition system. The 1st, 2nd and 3rd harmonic spectra are accomplished to show that it is possible to detect samples using the frequency quadruped system combined with the WMAS technique that can find practical applicability in the future.

  2. Spatial-Resolution Improvement in Optical Frequency Domain Reflectometry System Based on Tunable Linear Fiber Laser

    NASA Astrophysics Data System (ADS)

    Li, Guoyu; Zhao, Peng; Li, Yan

    2011-02-01

    In optical frequency domain reflectometry (OFDR) system, the spatial resolution is obtained by using the total frequency-sweep span of the tunable laser. However, in practice, the spatial resolution is severely limited by nonlinearity in the lightwave-frequency sweep of the tunable laser. A closed-loop PZT modulated DBR linear fiber laser is proposed to improve the spatial resolution of the OFDR system. Experimental results show that the spatial resolution of OFDR system has improved greatly. When the frequency sweep excursion is 66GHz and the fiber under test (FUT) is 7 m, the OFDR system has a spatial resolution of 1.5 m with open-loop PZT modulated laser. But the spatial resolution increases to 35 cm with closed-loop PZT modulated laser.

  3. Phase and Frequency Tracking-Accuracy in Direct-Detection Optical-Communication Systems.

    DTIC Science & Technology

    Lower bounds are given on the attainable mean-square performance in causally tracking the phase and frequency of a subcarrier that modulates an optical carrier in a direct-detection optical - communication system. (Author)

  4. Influence of crop rotation, intermediate crops, and organic fertilizers on the soil enzymatic activity and humus content in organic farming systems

    NASA Astrophysics Data System (ADS)

    Marcinkeviciene, A.; Boguzas, V.; Balnyte, S.; Pupaliene, R.; Velicka, R.

    2013-02-01

    The influence of crop rotation systems with different portions of nitrogen-fixing crops, intermediate crops, and organic fertilizers on the enzymatic activity and humus content of soils in organic farming was studied. The highest activity of the urease and invertase enzymes was determined in the soil under the crop rotation with 43% nitrogen-fixing crops and with perennial grasses applied twice per rotation. The application of manure and the growing of intermediate crops for green fertilizers did not provide any significant increase in the content of humus. The activity of urease slightly correlated with the humus content ( r = 0.30 at the significance level of 0.05 and r = 0.39 at the significance level of 0.01).

  5. Contributions to modeling functionality of a high frequency damper system

    NASA Astrophysics Data System (ADS)

    Sirbu, E. A.; Horga, S.; Vrabioiu, G.

    2016-08-01

    Due to the necessity of improving the handling performances of a motor vehicle, it is imperative to understand the suspensions properties that affects ride and directional respons.The construction of a fero-magnetic shock absorber is based on two bellows interconnected by a pipe-line. Through this pipe-line the fero-magnetic fluid is carried between the two bellows. The damping characteristic of the shock absorber is affected by the viscosity of the fero-magnetic fluid. The viscosity of the fluid, is controlled through a electric coil mounted on the bellows connecting pipe-line. Modifying the electrical field of the coil, the viscosity of the fluid will change, finally affecting the damping characteristic of the shock absorber. A recent system called „CCD Pothole Suspension” is implemented on Ford vehicles. By modifying the dampning characteristic of the shock absorbers, vehicle daynamics can be improved; also the risk of damaging the suspension will be decreased. The approach of this paper is to analyze the behaviour of the fero magnetic damper, thus determining how it will affect the performances of the vehicle suspensions. The experimental research will provide a better understanding of the behavior of the fero-magnetic shock absorber, and the possible advantages of using this system.

  6. Synchronization of Terrestrial Processes with Frequencies of the Earth-Moon System

    NASA Astrophysics Data System (ADS)

    Sidorenkov, N. S.

    It is established that the frequencies of the quasi-biennial oscillation (QBO) of atmospheric winds and the Chandler wobble (CW) of the Earth's poles are synchronized with each other and with the fundamental frequencies of the Earth-Moon-Sun system. The QBO and CW frequencies are resonance combinations of the frequencies of the Earth-Moon system's yearly rotation around the Sun, precessions of the lunar orbit, and the motion of its perigee. The QBO and CW frequencies are in a ratio of 1:2. The synchronizations between Mul'tanovskii's natural synoptic periods and tidal oscillations of the Earth's daily rotation rate, as well as between variations in climatic characteristics and long-time fluctuations of the Earth's rotation rate are described.

  7. Distributed Hierarchical Control of Multi-Area Power Systems with Improved Primary Frequency Regulation

    SciTech Connect

    Lian, Jianming; Marinovici, Laurentiu D.; Kalsi, Karanjit; Du, Pengwei; Elizondo, Marcelo A.

    2012-12-12

    The conventional distributed hierarchical control architecture for multi-area power systems is revisited. In this paper, a new distributed hierarchical control architecture is proposed. In the proposed architecture, pilot generators are selected in each area to be equipped with decentralized robust control as a supplementary to the conventional droop speed control. With the improved primary frequency control, the system frequency can be restored to the nominal value without the help of secondary frequency control, which reduces the burden of the automatic generation control for frequency restoration. Moreover, the low frequency inter-area electromechanical oscillations can also be effectively damped. The effectiveness of the proposed distributed hierarchical control architecture is validated through detailed simulations.

  8. Neural Network Model Of The PXIE RFQ Cooling System and Resonant Frequency Response

    SciTech Connect

    Edelen, Auralee; Biedron, Sandra; Bowring, Daniel; Chase, Brian; Edelen, Jonathan; Milton, Stephen; Steimel, Jim

    2016-06-01

    As part of the PIP-II Injector Experiment (PXIE) accel-erator, a four-vane radio frequency quadrupole (RFQ) accelerates a 30-keV, 1-mA to 10-mA H' ion beam to 2.1 MeV. It is designed to operate at a frequency of 162.5 MHz with arbitrary duty factor, including continuous wave (CW) mode. The resonant frequency is controlled solely by a water-cooling system. We present an initial neural network model of the RFQ frequency response to changes in the cooling system and RF power conditions during pulsed operation. A neural network model will be used in a model predictive control scheme to regulate the resonant frequency of the RFQ.

  9. The optimal control frequency response problem in manual control. [of manned aircraft systems

    NASA Technical Reports Server (NTRS)

    Harrington, W. W.

    1977-01-01

    An optimal control frequency response problem is defined within the context of the optimal pilot model. The problem is designed to specify pilot model control frequencies reflective of important aircraft system properties, such as control feel system dynamics, airframe dynamics, and gust environment, as well as man machine properties, such as task and attention allocation. This is accomplished by determining a bounded set of control frequencies which minimize the total control cost. The bounds are given by zero and the neuromuscular control frequency response for each control actuator. This approach is fully adaptive, i.e., does not depend upon user entered estimates. An algorithm is developed to solve this optimal control frequency response problem. The algorithm is then applied to an attitude hold task for a bare airframe fighter aircraft case with interesting dynamic properties.

  10. Intermediate-statistics spin waves

    NASA Astrophysics Data System (ADS)

    Dai, Wu-Sheng; Xie, Mi

    2009-04-01

    In this paper, we show that spin waves, the elementary excitation of the Heisenberg magnetic system, obey a kind of intermediate statistics with a finite maximum occupation number n. We construct an operator realization for the intermediate statistics obeyed by magnons, the quantized spin waves, and then construct a corresponding intermediate-statistics realization for the angular momentum algebra in terms of the creation and annihilation operators of the magnons. In other words, instead of the Holstein-Primakoff representation, a bosonic representation subject to a constraint on the occupation number, we present an intermediate-statistics representation with no constraints. In this realization, the maximum occupation number is naturally embodied in the commutation relation of creation and annihilation operators, while the Holstein-Primakoff representation is a bosonic operator relation with an additional putting-in-by-hand restriction on the occupation number. We deduce the intermediate-statistics distribution function for magnons from the intermediate-statistics commutation relation of the creation and annihilation operators directly, which is a modified Bose-Einstein distribution. On the basis of these results, we calculate the dispersion relations for ferromagnetic and antiferromagnetic spin waves. The relations between the intermediate statistics that magnons obey and the other two important kinds of intermediate statistics, Haldane-Wu statistics and the fractional statistics of anyons, are discussed. We also compare the spectrum of the intermediate-statistics spin wave with the exact solution of the one-dimensional s = 1/2 Heisenberg model, which is obtained by the Bethe ansatz method. For ferromagnets, we take the contributions from the interaction between magnons (the quartic contribution), the next-to-nearest-neighbor interaction, and the dipolar interaction into account for comparison with the experiment.

  11. Frequency of Oxygen VI in Intervening QSO Absorption Systems

    NASA Astrophysics Data System (ADS)

    Burles, Scott; Tytler, David

    1994-12-01

    We have conducted the first survey for QSO with O VI lambda lambda 1032,1038 absorption lines. We obtained medium resolution (R ~ 1300), high signal-to-noise (~ 20) spectra of 11 QSOs (0.53<= zem <=2.08) taken with the Faint Object Spectrograph from the Hubble Space Telescope Archive. The O VI doublet is found exclusively in the Lyman-alpha forest. All previous surveys of metal lines in QSO absorption systems were done redward of Lyalpha emission, avoiding blending due to Lyman-alpha forest clouds. The higher density of lines in the Lyman-alpha forest demands new stringent criteria to ensure the identification of the O VI doublet. We used simulated spectra to determine the statistical significance of lines indentified in the Lyman-alpha forest. We found 12 O VI doublets and 9 are expected to be real. Six constitute a uniform sample with both lines exceeding a rest equivalent width of W_r =0.21 Angstroms. The number of O VI doublets per unit redshift is = 1.0 +/-0.6 at a mean absorption redshift of zave = 0.9. For comparable W_r the density of O VI absorbers is similar to Mg II (Tytler et al 1986; Steidel & Sargent 1992) and C IV absorbers (Sargent et al 1988; Bahcall et al 1993). We searched for other common ions in the O VI absorption systems. Out of 8 O VI absorption systems in which C IV is also found, C IV is stronger in all except zabs=1.0828 towards PG1206+459 which we believe is collisionally ionized. A rough estimate of the cosmological mass density of O VI is carried out. If we assume that O VI lines are linear, we get a lower limit of Omega (OVI) >= 3 times 10(-9) h(-1}_{100) . Since O > O VI, if the mean metal abundance were below 0.002 solar, then the accompanying Hydrogen and Helium would account for all baryons in the universe. We conclude that mean abundances are above 0.002 solar, and much greater if the gas is not highly ionized (O >> O VI).

  12. Enhanced Recovery Utilizing Variable Frequency Drives and a Distributed Power System

    SciTech Connect

    Randy Peden; Sanjiv Shah

    2005-07-26

    This report describes complete results of the project entitled ''Enhanced Recovery Utilizing Variable Frequency Drives and a Distributed Power System''. This demonstration project was initiated in July 2003 and completed in March 2005. The objective of the project was to develop an integrated power production/variable frequency drive system that could easily be deployed in the oil field that would increase production and decrease operating costs. This report describes all the activities occurred and documents results of the demonstration.

  13. Distributed Optimization Design of Continuous-Time Multiagent Systems With Unknown-Frequency Disturbances.

    PubMed

    Wang, Xinghu; Hong, Yiguang; Yi, Peng; Ji, Haibo; Kang, Yu

    2017-05-24

    In this paper, a distributed optimization problem is studied for continuous-time multiagent systems with unknown-frequency disturbances. A distributed gradient-based control is proposed for the agents to achieve the optimal consensus with estimating unknown frequencies and rejecting the bounded disturbance in the semi-global sense. Based on convex optimization analysis and adaptive internal model approach, the exact optimization solution can be obtained for the multiagent system disturbed by exogenous disturbances with uncertain parameters.

  14. Frequency estimation for optical coherent M-QAM system without removing modulated data phase

    NASA Astrophysics Data System (ADS)

    Yu, Song; Cao, Yinwen; Leng, Haijun; Wu, Guohua; Gu, Wanyi

    2012-08-01

    For optical coherent M-ary quadrature amplitude modulation (M-QAM) system, the frequency offset can be extracted directly by applying Fast Fourier Transform (FFT) to the signal's argument, without removing the modulated data phase. By categorizing the constellation points and rotating some constellation points by π/4, this algorithm is robust to extract the frequency offset against the noise. Numerical simulations of 16-QAM and 256-QAM coherent systems are presented to demonstrate this algorithm.

  15. A systems-level model reveals that 1,2-Propanediol utilization microcompartments enhance pathway flux through intermediate sequestration

    PubMed Central

    Jakobson, Christopher M.; Slininger, Marilyn F.

    2017-01-01

    The spatial organization of metabolism is common to all domains of life. Enteric and other bacteria use subcellular organelles known as bacterial microcompartments to spatially organize the metabolism of pathogenicity-relevant carbon sources, such as 1,2-propanediol. The organelles are thought to sequester a private cofactor pool, minimize the effects of toxic intermediates, and enhance flux through the encapsulated metabolic pathways. We develop a mathematical model of the function of the 1,2-propanediol utilization microcompartment of Salmonella enterica and use it to analyze the function of the microcompartment organelles in detail. Our model makes accurate estimates of doubling times based on an optimized compartment shell permeability determined by maximizing metabolic flux in the model. The compartments function primarily to decouple cytosolic intermediate concentrations from the concentrations in the microcompartment, allowing significant enhancement in pathway flux by the generation of large concentration gradients across the microcompartment shell. We find that selective permeability of the microcompartment shell is not absolutely necessary, but is often beneficial in establishing this intermediate-trapping function. Our findings also implicate active transport of the 1,2-propanediol substrate under conditions of low external substrate concentration, and we present a mathematical bound, in terms of external 1,2-propanediol substrate concentration and diffusive rates, on when active transport of the substrate is advantageous. By allowing us to predict experimentally inaccessible aspects of microcompartment function, such as intra-microcompartment metabolite concentrations, our model presents avenues for future research and underscores the importance of carefully considering changes in external metabolite concentrations and other conditions during batch cultures. Our results also suggest that the encapsulation of heterologous pathways in bacterial

  16. A systems-level model reveals that 1,2-Propanediol utilization microcompartments enhance pathway flux through intermediate sequestration.

    PubMed

    Jakobson, Christopher M; Tullman-Ercek, Danielle; Slininger, Marilyn F; Mangan, Niall M

    2017-05-01

    The spatial organization of metabolism is common to all domains of life. Enteric and other bacteria use subcellular organelles known as bacterial microcompartments to spatially organize the metabolism of pathogenicity-relevant carbon sources, such as 1,2-propanediol. The organelles are thought to sequester a private cofactor pool, minimize the effects of toxic intermediates, and enhance flux through the encapsulated metabolic pathways. We develop a mathematical model of the function of the 1,2-propanediol utilization microcompartment of Salmonella enterica and use it to analyze the function of the microcompartment organelles in detail. Our model makes accurate estimates of doubling times based on an optimized compartment shell permeability determined by maximizing metabolic flux in the model. The compartments function primarily to decouple cytosolic intermediate concentrations from the concentrations in the microcompartment, allowing significant enhancement in pathway flux by the generation of large concentration gradients across the microcompartment shell. We find that selective permeability of the microcompartment shell is not absolutely necessary, but is often beneficial in establishing this intermediate-trapping function. Our findings also implicate active transport of the 1,2-propanediol substrate under conditions of low external substrate concentration, and we present a mathematical bound, in terms of external 1,2-propanediol substrate concentration and diffusive rates, on when active transport of the substrate is advantageous. By allowing us to predict experimentally inaccessible aspects of microcompartment function, such as intra-microcompartment metabolite concentrations, our model presents avenues for future research and underscores the importance of carefully considering changes in external metabolite concentrations and other conditions during batch cultures. Our results also suggest that the encapsulation of heterologous pathways in bacterial

  17. A frequency calibration system based on single chip processor and GPS signal

    NASA Astrophysics Data System (ADS)

    Li, Zhan; Zhang, Ying; Zhou, Wei

    2005-06-01

    A frequency callibration system based on INTEL 80C196KC single chip processor is introduced, dealing with the design principle, hardware composition and software realizing. The 1PPS signal from GPS receiver is applied to the calibration system in order to calibrate the frequency of the crystal oscillators, thus obtaining a time-frequency standard with good stability in both short-term and long-term. The quantized time delay method is adopted for comparison of short time intervals, and a Kalman filtering algorithm is applied to processing of the measuremetn data.

  18. A multiple deep attenuation frequency window for harmonic analysis in power systems

    SciTech Connect

    Daponte, P.; Falcomata, G. . Dept. di Elettronica Informatica e Sistemistica); Testa, A. . Dipt. di Ingegneria Elettrica)

    1994-04-01

    A novel window is presented and applied in electrical power system harmonic analysis. The goal of increasing the resolvability of low magnitude non-harmonic tones close in frequency to higher magnitude harmonics and the detectability of very low magnitude high frequency harmonics is pursued. The proposed window is derived from the Tseng window; its spectrum can be modeled in the synthesis stage and it is characterized by a narrow width main lobe and by sidelobes which are very low in correspondence to some specified frequencies. Numerical experiments demonstrate the performances and the usefulness of the new window in resolving periodic distorted waveforms in power systems.

  19. Adaptive Switching Technique for Space-Time/Frequency Coded OFDM Systems

    NASA Astrophysics Data System (ADS)

    Change, Namseok; Gil, Gye-Tae; Kang, Joonhyuk; Yu, Gangyoul

    In this letter, a switched transmission technique is presented that can provide the orthogonal frequency division multiplexing (OFDM) systems with additional diversity gain. The space-time block coding (STBC) and space-frequency block coding (SFBC) are considered for the transmission of the OFDM signals. A proper coding scheme is selected based on the estimated normalized delay spread and normalized Doppler spread. The selection criterion is derived empirically. It is shown through computer simulations that the proposed switching technique can improve the bit error rate (BER) performance of an OFDM system when the corresponding wireless channel has some time variation of time selectivity as well as frequency selectivity.

  20. Signal frequency based self-tuning fuzzy controller for semi-active suspension system.

    PubMed

    Sun, Tao; Huang, Zhen-Yu; Chen, Da-Yue; Tang, Lei

    2003-01-01

    A new kind of fuzzy control scheme, based on the identification of the signal's main frequency and the behavior of the ER damper, is proposed to control the semi-active suspension system. This method adjusts the fuzzy controller to achieve the best isolation effect by analyzing the main frequency's characters and inspecting the change of system parameters. The input of the fuzzy controller is the main frequency and the optimal damping ratio is the output. Simulation results indicated that the proposed control method is very effective in isolating the vibration.

  1. Multiple-frequency continuous wave ultrasonic system for accurate distance measurement

    NASA Astrophysics Data System (ADS)

    Huang, C. F.; Young, M. S.; Li, Y. C.

    1999-02-01

    A highly accurate multiple-frequency continuous wave ultrasonic range-measuring system for use in air is described. The proposed system uses a method heretofore applied to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. In the test embodiment to confirm concept feasibility, two low cost 40 kHz ultrasonic transducers are set face to face and used to transmit and receive ultrasound. Individual frequencies are transmitted serially, each generating its own phase shift. For any given frequency, the transmitter/receiver distance modulates the phase shift between the transmitted and received signals. Comparison of the phase shifts allows a highly accurate evaluation of target distance. A single-chip microcomputer-based multiple-frequency continuous wave generator and phase detector was designed to record and compute the phase shift information and the resulting distance, which is then sent to either a LCD or a PC. The PC is necessary only for calibration of the system, which can be run independently after calibration. Experiments were conducted to test the performance of the whole system. Experimentally, ranging accuracy was found to be within ±0.05 mm, with a range of over 1.5 m. The main advantages of this ultrasonic range measurement system are high resolution, low cost, narrow bandwidth requirements, and ease of implementation.

  2. A vibration isolation system in low frequency excitation region using negative stiffness structure for vehicle seat

    NASA Astrophysics Data System (ADS)

    Le, Thanh Danh; Ahn, Kyoung Kwan

    2011-12-01

    This paper designs and fabricates a vibration isolation model for improving vibration isolation effectiveness of the vehicle seat under low excitation frequencies. The feature of the proposed system is to use two symmetric negative stiffness structures (NSS) in parallel to a positive stiffness structure. Here, theoretical analysis of the proposed system is clearly presented. Then, the design procedure is derived so that the resonance peak of frequency-response curve drifts to the left, the load support capacity of the system is maintained, the total size of the system is reduced for easy practical application and especially, the bending of the frequency-response curve is minimized. Next the dynamic equation of the proposed system is set up. Then, the harmonic balance (HB) method is employed to seek the characteristic of the motion transmissibility of the proposed system at the steady state for each of the excitation frequency. From this characteristic, the curves of the motion transmission are predicted according to the various values of the configurative parameters of the system. Then, the time responses to the sinusoidal, multi frequency and random excitations are also investigated by simulation and experiment. In addition, the isolation performance comparison between the system with NSS and system without NSS is realized. The simulation results reveal that the proposed system has larger frequency region of isolation than that of the system without NSS. The experimental results confirm also that with a random excitation mainly spreading from 0.1 to 10 Hz, the isolation performance of the system with NSS is greatly improved, where the RMS values of the mass displacement may be reduced to 67.2%, whereas the isolation performance of the system without NSS is bad. Besides, the stability of the steady-state response is also studied. Finally, some conclusions are given.

  3. Participation of non-conventional energy resources in power system frequency control

    NASA Astrophysics Data System (ADS)

    Aghazadeh Tabrizi, Mehriar

    Frequency control is one of the key issues in designing, planning and reliably operating a power system and is becoming more challenging as new complexities and uncertainties are introduced into the modern power systems. Traditionally, power system frequency has been controlled using conventional generation units' capabilities namely inertial, primary and secondary frequency responses. Limited fossil-based fuel resources, ever-increasing energy consumption and rising public awareness for environmental protection have created growing interest in use of non-conventional energy resources such as Wind Generation Resources (WGRs) and Solar Generation Resources (SGRs) which have unfavorable characteristics in comparison with conventional generation units such as lack of frequency response. The more conventional generation units are replaced by these resources, the more challenges power system operators will face in terms of power system frequency control. These challenges are further compounded due to less system inertia during off-peak hours or within small power systems. This dissertation mainly focuses on participation of SGRs and Interior Permanent Magnet Synchronous Generator (IPMSG) based WGRs in power system frequency control. Detailed information regarding dynamic modeling of power system including conventional generation units, SGRs and IPMSG based WGRs is provided. The frequency response of conventional generation units is compared with that of SGRs and IPMSG based WGRs. The control systems associated with IPMSG based WGR and SGR are modified in order to improve their frequency response capabilities. The effectiveness of the proposed control strategies is evaluated and confirmed via MATLAB based time-domain simulations for different scenarios. Moreover, application of Battery Energy Storage Systems (BESSs) in power system frequency regulation is discussed. The detailed dynamic model of BESSs is utilized to develop a simplified model suitable for Automatic

  4. Coupled solitons of intense high-frequency and low-frequency waves in Zakharov-type systems

    NASA Astrophysics Data System (ADS)

    Gromov, Evgeny; Malomed, Boris

    2016-12-01

    One-parameter families of exact two-component solitary-wave solutions for interacting high-frequency (HF) and low-frequency (LF) waves are found in the framework of Zakharov-type models, which couple the nonlinear Schrödinger equation for intense HF waves to the Boussinesq (Bq) or Korteweg-de Vries (KdV) equation for the LF component through quadratic terms. The systems apply, in particular, to the interaction of surface (HF) and internal (LF) waves in stratified fluids. These solutions are two-component generalizations of the single-component Bq and KdV solitons. Perturbed dynamics and stability of the solitary waves are studied in detail by means of analytical and numerical methods. Essentially, they are stable against separation of the HF and LF components if the latter one is shaped as a potential well acting on the HF field, and unstable, against splitting of the two components, with a barrier-shaped LF one. Collisions between the solitary waves are studied by means of direct simulations, demonstrating a trend to merger of in-phase solitons, and elastic interactions of out-of-phase ones.

  5. Coupled solitons of intense high-frequency and low-frequency waves in Zakharov-type systems.

    PubMed

    Gromov, Evgeny; Malomed, Boris

    2016-12-01

    One-parameter families of exact two-component solitary-wave solutions for interacting high-frequency (HF) and low-frequency (LF) waves are found in the framework of Zakharov-type models, which couple the nonlinear Schrödinger equation for intense HF waves to the Boussinesq (Bq) or Korteweg-de Vries (KdV) equation for the LF component through quadratic terms. The systems apply, in particular, to the interaction of surface (HF) and internal (LF) waves in stratified fluids. These solutions are two-component generalizations of the single-component Bq and KdV solitons. Perturbed dynamics and stability of the solitary waves are studied in detail by means of analytical and numerical methods. Essentially, they are stable against separation of the HF and LF components if the latter one is shaped as a potential well acting on the HF field, and unstable, against splitting of the two components, with a barrier-shaped LF one. Collisions between the solitary waves are studied by means of direct simulations, demonstrating a trend to merger of in-phase solitons, and elastic interactions of out-of-phase ones.

  6. High frequency data acquisition system for space shuttle main engine testing

    NASA Technical Reports Server (NTRS)

    Lewallen, Pat

    1987-01-01

    The high frequency data acquisition system developed for the Space Shuttle Main Engine (SSME) single engine test facility at the National Space Technology Laboratories is discussed. The real time system will provide engineering data for a complete set of SSME instrumentation (approx. 100 measurements) within 4 hours following engine cutoff, a decrease of over 48 hours from the previous analog tape based system.

  7. System stability and calibrations for hand-held electromagnetic frequency domain instruments

    NASA Astrophysics Data System (ADS)

    Saksa, Pauli J.; Sorsa, Joona

    2017-05-01

    There are a few multiple-frequency domain electromagnetic induction (EMI) hand-held rigid boom systems available for shallow geophysical resistivity investigations. They basically measure secondary field real and imaginary components after the system calibrations. One multiple-frequency system, the EMP-400 Profiler from Geophysical Survey Systems Inc., was tested for system calibrations, stability and various effects present in normal measurements like height variation, tilting, signal stacking and time stability. Results indicated that in test conditions, repeatable high-accuracy imaginary component values can be recorded for near-surface frequency soundings. In test conditions, real components are also stable but vary strongly in normal surveying measurements. However, certain calibration issues related to the combination of user influence and measurement system height were recognised as an important factor in reducing for data errors and for further processing like static offset corrections.

  8. Radio frequency seismic gathering system employing an airborne blimp

    SciTech Connect

    Imm, R.A.; McDavid, W.T.; Mckeever, J.M.

    1980-11-25

    The central station of a radio-connected seismic surveying system uses a tethered blimp carrying an antenna and an electronics package including a dc voltage/rf decoupler, a variable dc controlled preamplifier, a p-i-n diode switch for changing the antenna from receive to transmit operation, a transmitter and modulator and a battery. An rf coaxial cable to ground provides means for controlling the preamplifier gain and for switching the central station to the transmit mode by using appropriate dc signals. In the receive mode, the cable carries detected field unit seismic signals, which are detected by the blimp-carried antenna and preamplified by the blimp preamplifier, to the ground for suitable recording and further processing in the ground portion of the central station. An audio channel can also be modulated onto the transmit carrier of approximately 70 mhz to provide voice communications via the blimp electronics, if desired. Both the ground portion and the blimp portion of the central station are packaged for helicopter transporting.

  9. Coherence and frequency in the reticular activating system (RAS).

    PubMed

    Garcia-Rill, Edgar; Kezunovic, Nebojsa; Hyde, James; Simon, Christen; Beck, Paige; Urbano, Francisco J

    2013-06-01

    This review considers recent evidence showing that cells in the reticular activating system (RAS) exhibit (1) electrical coupling mainly in GABAergic cells, and (2) gamma band activity in virtually all of the cells. Specifically, cells in the mesopontine pedunculopontine nucleus (PPN), intralaminar parafascicular nucleus (Pf), and pontine dorsal subcoeruleus nucleus dorsalis (SubCD) (1) show electrical coupling, and (2) all fire in the beta/gamma band range when maximally activated, but no higher. The mechanism behind electrical coupling is important because the stimulant modafinil was shown to increase electrical coupling. We also provide recent findings demonstrating that all cells in the PPN and Pf have high threshold, voltage-dependent P/Q-type calcium channels that are essential to gamma band activity. On the other hand, all SubCD, and some PPN, cells manifested sodium-dependent subthreshold oscillations. A novel mechanism for sleep-wake control based on transmitter interactions, electrical coupling, and gamma band activity is described. We speculate that continuous sensory input will modulate coupling and induce gamma band activity in the RAS that could participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions.

  10. Evaluation of the efficacy of four weak acids as antifungal preservatives in low-acid intermediate moisture model food systems.

    PubMed

    Huang, Yang; Wilson, Mark; Chapman, Belinda; Hocking, Ailsa D

    2010-02-01

    The potential efficacy of four weak acids as preservatives in low-acid intermediate moisture foods was assessed using a glycerol based agar medium. The minimum inhibitory concentrations (MIC, % wt./wt.) of each acid was determined at two pH values (pH 5.0, pH 6.0) and two a(w) values (0.85, 0.90) for five food spoilage fungi, Eurotium herbariorum, Eurotium rubrum, Aspergillus niger, Aspergillus flavus and Penicillium roqueforti. Sorbic acid, a preservative commonly used to control fungal growth in low-acid intermediate moisture foods, was included as a reference. The MIC values of the four acids were lower at pH 5.0 than pH 6.0 at equivalent a(w) values, and lower at 0.85 a(w) than 0.90 a(w) at equivalent pH values. By comparison with the MIC values of sorbic acid, those of caprylic acid and dehydroacetic acid were generally lower, whereas those for caproic acid were generally higher. No general observation could be made in the case of capric acid. The antifungal activities of all five weak acids appeared related not only to the undissociated form, but also the dissociated form, of each acid.

  11. Carrier-interference ratios for frequency sharing between frequency-modulated amplitude-modulated-vestigial-sideband television systems

    NASA Technical Reports Server (NTRS)

    Barnes, S. P.; Miller, E. F.

    1978-01-01

    For just perceptible interference, an FM television signal interfering with another FM television signal must have an average signal power that is 26 to 37 db less than the wanted signal power. For an AM-VSB television signal interfering with an FM television signal, the AM-VSB television's sync peak average power must be 18 to 31 db below the FM television signal's average power. Also, when an FM television signal interferes with an AM-VSB signal, the average signal power of the FM signal should be 56 to 59 db below the sync peak average power of the AM-VSB television signal. The range of power ratios occur as a result of different TV scenes used in the tests and different FM-signal frequency deviations used. All tests were performed using 525 line, system M, color-television signals.

  12. Ultra-wide frequency response measurement of an optical system with a DC photo-detector

    NASA Astrophysics Data System (ADS)

    Kuntz, Katanya B.; Wheatley, Trevor A.; Song, Hongbin; Webb, James G.; Mabrok, Mohamed A.; Huntington, Elanor H.; Yonezawa, Hidehiro

    2017-01-01

    Precise knowledge of an optical device's frequency response is crucial for it to be useful in most applications. Traditional methods for determining the frequency response of an optical system (e.g. optical cavity or waveguide modulator) usually rely on calibrated broadband photo-detectors or complicated RF mixdown operations. As the bandwidths of these devices continue to increase, there is a growing need for a characterization method that does not have bandwidth limitations, or require a previously calibrated device. We demonstrate a new calibration technique on an optical system (consisting of an optical cavity and a high-speed waveguide modulator) that is free from limitations imposed by detector bandwidth, and does not require a calibrated photo-detector or modulator. We use a low-frequency (DC) photo-detector to monitor the cavity's optical response as a function of modulation frequency, which is also used to determine the modulator's frequency response. Knowledge of the frequency-dependent modulation depth allows us to more precisely determine the cavity's characteristics (free spectral range and linewidth). The precision and repeatability of our technique is demonstrated by measuring the different resonant frequencies of orthogonal polarization cavity modes caused by the presence of a non-linear crystal. Once the modulator has been characterized using this simple method, the frequency response of any passive optical element can be determined.

  13. A combined method for computing frequency responses of proportionally damped systems

    NASA Astrophysics Data System (ADS)

    Wu, Baisheng; Yang, Shitong; Li, Zhengguang; Zheng, Shaopeng

    2015-08-01

    Frequency response analysis requires the evaluation of an associated function for a typically large number of frequencies. Direct method for performing these calculations is time-consuming. In this paper, a method is proposed for solving frequency responses of a mechanical system with proportional damping. The method combines modal superposition with a model order reduction. Only the modes corresponding to a frequency range which is a little bigger than that of interest are used for modal superposition. Complementary part of contribution of computed modes for frequency response is calculated by a model order reduction method. Basis vectors are obtained by applying preconditioned conjugate gradient method to a modified undamped system at the highest frequency of interest. The existing factorized stiffness matrix developed for partial eigensolutions is used as preconditioner. This computational methodology is illustrated by its applications to two frequency response problems. It is shown that the present method can remarkably reduce the CPU time required by the direct method to frequency response analysis.

  14. Investigating Power System Primary and Secondary Reserve Interaction under High Wind Penetration Using Frequency Response Model

    SciTech Connect

    Tan, Jin; Zhang, Yingchen; Krad, Ibrahim; Gevorgian, Vahan; Ela, Erik

    2015-10-12

    Power system frequency needs to be maintained close to its nominal value at all times to avoid machine damage, under-frequency load-shedding and even blackouts. Adequate primary frequency response and secondary frequency response are the primary forces to correct an energy imbalance at the second to minute level. As wind energy becomes a larger portion of the world's energy portfolio, there are greater oppotunities for wind to provide frequency response services. This paper addresses one area of frequency control that has been missing in previous work - the reliabilty impacts and interactions between primary and secondary frequency control. The lack of a commercially available tools to simulate the interaction of these two responses has limited the energy industry's understanding of when the depletion of primary control reserve will impact the performance of secondary conrol response or vice versa. To investigate this issue, in this paper we develop a multi-area frequency response integration model with combined primary and secondary frequency control capabilities.

  15. An ultra-broadband frequency-domain terahertz measurement system based on frequency conversion via DAST crystal with an optimized phase-matching condition

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    By applying the frequency conversion technique to 4-dimethylamino-N-methyl-4-stilbazolium tosylate crystal, a monochromatic terahertz (THz) measurement system, including both generation and detection, has been developed over quite a broad frequency band, from 1.85 to 30 THz. In the case of frequency upconversion detection of THz waves, for the first time, we used gratings instead of filters to tackle the tough phase-matching conditions for broadband operations. By synchronizing the rotation of two gratings to extract the frequency upconverted signal, the infrared (IR) pumping beam can be tuned freely over 300 nm with decent diffraction efficiency and sufficient isolation between the weak frequency upconversion signal and the strong IR pumping beam to be realized. Such a large tuning range has overcome the limit of commercial filters with a fixed passband, while such a high optical density value has been beyond the limit of commercial tunable filters. Consequently, the proposed frequency domain system gives the largest THz frequency band. Unlike THz time-domain spectroscopy systems in which a fs laser is applied and broadband THz pulses are applied, our system works based on a ns laser and it can function at a single THz frequency with random frequency access ability from pulse to pulse.

  16. Intrinsic frequency for a systems approach to haemodynamic waveform analysis with clinical applications.

    PubMed

    Pahlevan, Niema M; Tavallali, Peyman; Rinderknecht, Derek G; Petrasek, Danny; Matthews, Ray V; Hou, Thomas Y; Gharib, Morteza

    2014-09-06

    The reductionist approach has dominated the fields of biology and medicine for nearly a century. Here, we present a systems science approach to the analysis of physiological waveforms in the context of a specific case, cardiovascular physiology. Our goal in this study is to introduce a methodology that allows for novel insight into cardiovascular physiology and to show proof of concept for a new index for the evaluation of the cardiovascular system through pressure wave analysis. This methodology uses a modified version of sparse time-frequency representation (STFR) to extract two dominant frequencies we refer to as intrinsic frequencies (IFs; ω1 and ω2). The IFs are the dominant frequencies of the instantaneous frequency of the coupled heart + aorta system before the closure of the aortic valve and the decoupled aorta after valve closure. In this study, we extract the IFs from a series of aortic pressure waves obtained from both clinical data and a computational model. Our results demonstrate that at the heart rate at which the left ventricular pulsatile workload is minimized the two IFs are equal (ω1 = ω2). Extracted IFs from clinical data indicate that at young ages the total frequency variation (Δω = ω1 - ω2) is close to zero and that Δω increases with age or disease (e.g. heart failure and hypertension). While the focus of this paper is the cardiovascular system, this approach can easily be extended to other physiological systems or any biological signal.

  17. An Auto-Lock Laser System for Long Term Frequency Stabilization

    NASA Astrophysics Data System (ADS)

    Berthiaume, Robert; Vorozcovs, Andrew; Kumarakrishnan, A.

    2010-03-01

    We have developed a compact, digitally controlled system to automatically stabilize the frequency of an external cavity diode laser to an atomic resonance. The key component of the system is a low-cost single-board computer with A/D and D/A capability that acts as a specialized lock-in amplifier. The system performs pattern matching between Doppler-free peaks obtained by scanning the laser frequency and reference peaks stored in the processor's memory. The incoming spectral signals are compared with the reference waveforms using a sliding correlation algorithm, which determines the control voltage required for adjusting the laser frequency to the desired lock point. The system has a scan amplitude of less than 1MHz when locked and it can re-lock for frequency drifts up to 10 GHz without human intervention. The dependence of laser frequency stability on ambient temperature, humidity, and pressure has been investigated. The performance of the system is suitable for experiments in atom trapping and atom interferometry that require long-term laser frequency stabilization.

  18. The study of the emission frequency control system stability in hydropulse generator

    NASA Astrophysics Data System (ADS)

    Kapelyuhovskiy, Andrey A.; Kapelyuhovskaya, Alexandra A.; Stepanova, Elena P.

    2017-08-01

    During a low-frequency acoustic treatment of the oil-bearing formation, downhole hydraulic vibrators are used. Their efficient operation is possible when using the automatic frequency control system due to the change of the expenditure pump flow rate. A long hydraulic line specifies additional requirements to the parameters of the control system in terms of its stability. The stability of a control system using the Nyquist criterion is made. Approximating the delay by the second degree of the Pade polynomial, the stability region is determined by the D-decomposition method. The dependence of the critical delay on the system transfer ratio is found out.

  19. Use of phase information with a stepper motor to control frequency for tuning system of the Front End Test Stand Radio Frequency Quadrupole at Rutherford Appleton Laboratory

    NASA Astrophysics Data System (ADS)

    Alsari, S.; Aslaninejad, M.; Pozimski, J.

    2015-03-01

    For the Front End Test Stand (FETS) linear accelerator project at the Rutherford Appleton Laboratory in the UK, a 4 m, 4 vanes Radio Frequency Quadrupole (RFQ) with a resonant frequency of 324 MHz has been designed. The RF power feeding the RFQ gives rise to the temperature increase in the RFQ, which in turn, results in shifting the resonant frequency of the RFQ. The frequency shift and the stability in the RFQ frequency can be maintained based on the reflected power or signal phase information. We have, however, investigated restoration of the RFQ nominal frequency based on the RF signal phases driving a stepper motor. The concept and the system set-up and electronics are described in detail. Results of the measurements indicating the full restoration of the RFQ nominal frequency based on the RF signal phases and stepper motor are presented. Moreover, measured sensitivity of tuner with respect to its position is given.

  20. Astronomical Verification of a Stabilized Frequency Reference Transfer System for the Square Kilometer Array

    NASA Astrophysics Data System (ADS)

    Gozzard, David R.; Schediwy, Sascha W.; Dodson, Richard; Rioja, María J.; Hill, Mike; Lennon, Brett; McFee, Jock; Mirtschin, Peter; Stevens, Jamie; Grainge, Keith

    2017-07-01

    In order to meet its cutting-edge scientific objectives, the Square Kilometre Array (SKA) telescope requires high-precision frequency references to be distributed to each of its antennas. The frequency references are distributed via fiber-optic links and must be actively stabilized to compensate for phase noise imposed on the signals by environmental perturbations on the links. SKA engineering requirements demand that any proposed frequency reference distribution system be proved in “astronomical verification” tests. We present results of the astronomical verification of a stabilized frequency reference transfer system proposed for SKA-mid. The dual-receiver architecture of the Australia Telescope Compact Array was exploited to subtract the phase noise of the sky signal from the data, allowing the phase noise of observations performed using a standard frequency reference, as well as the stabilized frequency reference transfer system transmitting over 77 km of fiber-optic cable, to be directly compared. Results are presented for the fractional frequency stability and phase drift of the stabilized frequency reference transfer system for celestial calibrator observations at 5 and 25 GHz. These observations plus additional laboratory results for the transferred signal stability over a 166 km metropolitan fiber-optic link are used to show that the stabilized transfer system under test exceeds all SKA phase-stability requirements within a broad range of observing conditions. Furthermore, we have shown that alternative reference dissemination systems that use multiple synthesizers to supply reference signals to sub-sections of an array may limit the imaging capability of the telescope.

  1. Frequency tracking in acoustic trapping for improved performance stability and system surveillance.

    PubMed

    Hammarström, Björn; Evander, Mikael; Wahlström, Jacob; Nilsson, Johan

    2014-03-07

    This work proposes and demonstrates an acoustic trapping system where the trapping frequency is automatically determined and can be used to analyse changes in the acoustic trap. Critical for the functionality of this system is the use of a kerfed transducer that removes spurious resonances. This makes it possible to determine the optimal trapping frequency by analysing electrical impedance. It is demonstrated that the novel combination of a kerfed transducer and acoustic trapping in glass capillaries creates a high Q-value resonator. This narrows the frequency bandwidth but allows excellent performance, as confirmed by a ten-fold increase in the flow retention speed when compared to previously reported values. Importantly, the use of automatic frequency tracking allows the use of such a narrow bandwidth resonator without compromising system stability. As changes in temperature, buffer-properties, and the amount of captured particles will affect the properties of the acoustic resonator, corresponding changes in resonance frequency will occur. It is shown that such frequency changes can be accurately tracked using the setup. Therefore, monitoring the frequency over time adds a new feature to acoustic trapping, where experimental progress can be monitored and the amount of trapped material can be quantified.

  2. Microwave signal processing in two-frequency domain for ROF systems implementation: training course

    NASA Astrophysics Data System (ADS)

    Morozov, Oleg G.; Morozov, Gennady A.

    2014-04-01

    This article is presented materials from two tutorials: "Optical two-frequency domain reflectometry1, 2" and "Microwave technologies in industry, living systems and telecommunications3". These materials were prepared for master training courses and listed in the "SPIE Optical Education Directory" for 2013/2014. The main its theme is microwave photonics. Microwave photonics has been defined as the study of photonic devices operating at microwave frequencies and their application to microwave and optical systems. Its initial rationale was to use the advantages of photonic technologies to provide functions in microwave systems that are very complex or even impossible to carry out directly in the radiofrequency domain. But microwave photonics is also succeeding in incorporating a variety of techniques used in microwave engineering to improve the performance of photonic communication networks and systems. Three parts of this chapter are devoted to applications and construction principles of systems forming microwave photonic filters, measuring instantaneous frequency of microwave heterodyne signals and characterizing stimulated Mandelstam- Brillouin scattering spectrum in ROF systems. The main emphasis is on the use of the two-frequency symmetric radiation, generated by the Il'in-Morozov's method4, in given systems. It is forming radiation for the synthesis of optical filters coefficients, it's application and processing determine the increase in the signal-to-noise ratio during heterodyne frequencies monitoring and characterization of nonlinear effects spectrum.

  3. CFAVC scheme for high frequency series resonant inverter-fed domestic induction heating system

    NASA Astrophysics Data System (ADS)

    Nagarajan, Booma; Reddy Sathi, Rama

    2016-01-01

    This article presents the investigations on the constant frequency asymmetric voltage cancellation control in the AC-AC resonant converter-fed domestic induction heating system. Conventional fixed frequency control techniques used in the high frequency converters lead to non-zero voltage switching operation and reduced output power. The proposed control technique produces higher output power than the conventional fixed-frequency control strategies. In this control technique, zero-voltage-switching operation is maintained during different duty cycle operation for reduction in the switching losses. Complete analysis of the induction heating power supply system with asymmetric voltage cancellation control is discussed in this article. Simulation and experimental study on constant frequency asymmetric voltage cancellation (CFAVC)-controlled full bridge series resonant inverter is performed. Time domain simulation results for the open and closed loop of the system are obtained using MATLAB simulation tool. The simulation results prove the control of voltage and power in a wide range. PID controller-based closed loop control system achieves the voltage regulation of the proposed system for the step change in load. Hardware implementation of the system under CFAVC control is done using the embedded controller. The simulation and experimental results validate the performance of the CFAVC control technique for series resonant-based induction cooking system.

  4. Improving transient performance of adaptive control architectures using frequency-limited system error dynamics

    NASA Astrophysics Data System (ADS)

    Yucelen, Tansel; De La Torre, Gerardo; Johnson, Eric N.

    2014-11-01

    Although adaptive control theory offers mathematical tools to achieve system performance without excessive reliance on dynamical system models, its applications to safety-critical systems can be limited due to poor transient performance and robustness. In this paper, we develop an adaptive control architecture to achieve stabilisation and command following of uncertain dynamical systems with improved transient performance. Our framework consists of a new reference system and an adaptive controller. The proposed reference system captures a desired closed-loop dynamical system behaviour modified by a mismatch term representing the high-frequency content between the uncertain dynamical system and this reference system, i.e., the system error. In particular, this mismatch term allows the frequency content of the system error dynamics to be limited, which is used to drive the adaptive controller. It is shown that this key feature of our framework yields fast adaptation without incurring high-frequency oscillations in the transient performance. We further show the effects of design parameters on the system performance, analyse closeness of the uncertain dynamical system to the unmodified (ideal) reference system, discuss robustness of the proposed approach with respect to time-varying uncertainties and disturbances, and make connections to gradient minimisation and classical control theory. A numerical example is provided to demonstrate the efficacy of the proposed architecture.

  5. Frequency and timing system for the consolidated DSN and STDN tracking network

    NASA Technical Reports Server (NTRS)

    Coffin, R. C.; Johnson, D. E.; Kuhnle, P. F.

    1981-01-01

    The consolidation on the existing Deep Space Network (DSN) and colocated Goddard Spaceflight Tracking and Data Network (STDN) stations into a multiple antenna array is discussed. Each site includes a signal processing center (SPC) centered in an array of four or five antennas each located within approximately 300 to 800 meters of the SPC. A central frequency and timing system (FTS) located in the SPC contains reference frequency, timing and time code generation, and distribution equipment for both the SPC and each antenna with its associated front end antenna control building. The reference frequency distribution and clock equipment are driven by a hydrogen maser as the prime frequency standard with cesium beam frequency standard as the secondary.

  6. Multipixel system for gigahertz frequency-domain optical imaging of finger joints

    NASA Astrophysics Data System (ADS)

    Netz, Uwe J.; Beuthan, Jürgen; Hielscher, Andreas H.

    2008-03-01

    Frequency-domain optical imaging systems have shown great promise for characterizing blood oxygenation, hemodynamics, and other physiological parameters in human and animal tissues. However, most of the frequency domain systems presented so far operate with source modulation frequencies below 150MHz. At these low frequencies, their ability to provide accurate data for small tissue geometries such as encountered in imaging of finger joints or rodents is limited. Here, we present a new system that can provide data up to 1GHz using an intensity modulated charged coupled device camera. After data processing, the images show the two-dimensional distribution of amplitude and phase of the light modulation on the finger surface. The system performance was investigated and test measurements on optical tissue phantoms were taken to investigate whether higher frequencies yield better signal-to-noise ratios (SNRs). It could be shown that local changes in optical tissue properties, as they appear in the initial stages of rheumatoid arthritis in a finger joint, are detectable by simple image evaluation, with the range of modulation frequency around 500MHz proving to yield the highest SNR.

  7. Multipixel system for gigahertz frequency-domain optical imaging of finger joints.

    PubMed

    Netz, Uwe J; Beuthan, Jürgen; Hielscher, Andreas H

    2008-03-01

    Frequency-domain optical imaging systems have shown great promise for characterizing blood oxygenation, hemodynamics, and other physiological parameters in human and animal tissues. However, most of the frequency domain systems presented so far operate with source modulation frequencies below 150 MHz. At these low frequencies, their ability to provide accurate data for small tissue geometries such as encountered in imaging of finger joints or rodents is limited. Here, we present a new system that can provide data up to 1 GHz using an intensity modulated charged coupled device camera. After data processing, the images show the two-dimensional distribution of amplitude and phase of the light modulation on the finger surface. The system performance was investigated and test measurements on optical tissue phantoms were taken to investigate whether higher frequencies yield better signal-to-noise ratios (SNRs). It could be shown that local changes in optical tissue properties, as they appear in the initial stages of rheumatoid arthritis in a finger joint, are detectable by simple image evaluation, with the range of modulation frequency around 500 MHz proving to yield the highest SNR.

  8. para-Nitroaniline is a Promising Matrix for MALDI-MS Imaging on Intermediate Pressure MS Systems

    NASA Astrophysics Data System (ADS)

    Steven, Rory T.; Race, Alan M.; Bunch, Josephine

    2013-05-01

    para-Nitroaniline (PNA) is presented as a promising matrix for matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) on an intermediate-pressure ion source (~1 Torr) QqTOF instrument using an Nd:YVO4 laser operated at 5 kHz. An imaging study was carried out to determine the utility of PNA at this pressure by analyzing 14 tissue sections. We demonstrate acquisition of high-quality imaging data over a 6-h period in the ion source. In this study, comparisons were made between PNA and α-cyano-4-hydroxycinnamic acid (CHCA) in positive ion mode to demonstrate the utility of PNA in these circumstances. PNA performed as well as or better than CHCA in terms of lipid ion intensities, resulting in lower levels of ion fragmentation and in lower incidences of analyte migration at the edges of the tissue sections when using airspray matrix deposition.

  9. High frequency vibration characteristics of electric wheel system under in-wheel motor torque ripple

    NASA Astrophysics Data System (ADS)

    Mao, Yu; Zuo, Shuguang; Wu, Xudong; Duan, Xianglei

    2017-07-01

    With the introduction of in-wheel motor, the electric wheel system encounters new vibration problems brought by motor torque ripple excitation. In order to analyze new vibration characteristics of electric wheel system, torque ripple of in-wheel motor based on motor module and vector control system is primarily analyzed, and frequency/order features of the torque ripple are discussed. Then quarter vehicle-electric wheel system (QV-EWS) dynamics model based on the rigid ring tire assumption is established and the main parameters of the model are identified according to tire free modal test. Modal characteristics of the model are further analyzed. The analysis indicates that torque excitation of in-wheel motor is prone to arouse horizontal vibration, in which in-phase rotational, anti-phase rotational and horizontal translational modes of electric wheel system mainly participate. Based on the model, vibration responses of the QV-EWS under torque ripple are simulated. The results show that unlike vertical low frequency (lower than 20 Hz) vibration excited by road roughness, broadband torque ripple will arouse horizontal high frequency (50-100 Hz) vibration of electric wheel system due to participation of the three aforementioned modes. To verify the theoretical analysis, the bench experiment of electric wheel system is conducted and vibration responses are acquired. The experiment demonstrates the high frequency vibration phenomenon of electric wheel system and the measured order features as well as main resonant frequencies agree with simulation results. Through theoretical modeling, analysis and experiments this paper reveals and explains the high frequency vibration characteristics of electric wheel system, providing references for the dynamic analysis, optimal design of QV-EWS.

  10. Higher-order vibrational mode frequency tuning utilizing fishbone-shaped microelectromechanical systems resonator

    NASA Astrophysics Data System (ADS)

    Suzuki, Naoya; Tanigawa, Hiroshi; Suzuki, Kenichiro

    2013-04-01

    Resonators based on microelectromechanical systems (MEMS) have received considerable attention for their applications for wireless equipment. The requirements for this application include small size, high frequency, wide bandwidth and high portability. However, few MEMS resonators with wide-frequency tuning have been reported. A fishbone-shaped resonator has a resonant frequency with a maximum response that can be changed according to the location and number of several exciting electrodes. Therefore, it can be expected to provide wide-frequency tuning. The resonator has three types of electrostatic forces that can be generated to deform a main beam. We evaluate the vibrational modes caused by each exciting electrodes by comparing simulated results with measured ones. We then successfully demonstrate the frequency tuning of the first to fifth resonant modes by using the algorithm we propose here. The resulting frequency tuning covers 178 to 1746 kHz. In addition, we investigate the suppression of the anchor loss to enhance the Q-factor. An experiment shows that tapered-shaped anchors provide a higher Q-factor than rectangular-shaped anchors. The Q-factor of the resonators supported by suspension beams is also discussed. Because the suspension beams cause complicated vibrational modes for higher frequencies, the enhancement of the Q-factor for high vibrational modes cannot be obtained here. At present, the tapered-anchor resonators are thought to be most suitable for frequency tuning applications.

  11. Development of a high-frequency and large-stroke fatigue testing system for rubber

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Wu, Hao; Gao, Jianwen; Lin, Qiang

    2017-04-01

    The limited capabilities of current fatigue testing machines have resulted in studies on the fatigue behavior of rubber under large-displacement amplitude and high frequency being very sparse. In this study, a fatigue testing system that can carry out large-displacement amplitude and high-frequency fatigue tests on rubber was developed using a moving magnet voice coil motor (MMVCM) actuator, with finite element analysis applied to analyze the thrust of the MMVCM actuator. The results of a series of cyclic tension tests conducted on vulcanized natural rubber specimens using the developed fatigue testing system verify that it has high precision, low noise, large-stroke, and high-frequency characteristics. Further, the load frame with the developed MMVCM actuator is feasible for material testing, especially for large-stroke and high-frequency fatigue tests.

  12. Impact of the frequency dependence of tidal Q on the evolution of planetary systems

    NASA Astrophysics Data System (ADS)

    Auclair-Desrotour, P.; Le Poncin-Lafitte, C.; Mathis, S.

    2014-01-01

    Context. Tidal dissipation in planets and in stars is one of the key physical mechanisms that drive the evolution of planetary systems. Aims: Tidal dissipation properties are intrinsically linked to the internal structure and the rheology of the studied celestial bodies. The resulting dependence of the dissipation upon the tidal frequency is strongly different in the cases of solids and fluids. Methods: We computed the tidal evolution of a two-body coplanar system, using the tidal-quality factor frequency-dependencies appropriate to rocks and to convective fluids. Results: The ensuing orbital dynamics is smooth or strongly erratic, depending on the way the tidal dissipation depends upon frequency. Conclusions: We demonstrate the strong impact of the internal structure and of the rheology of the central body on the orbital evolution of the tidal perturber. A smooth frequency-dependence of the tidal dissipation causes a smooth orbital evolution, while a peaked dissipation can produce erratic orbital behaviour.

  13. Intelligent two-loop time-division-multiplexing (TDM) optical frequency stabilization system for multichannel communications

    NASA Astrophysics Data System (ADS)

    Li, Aiguo; Wu, Deming; Xie, Linzhen

    1995-04-01

    A channel spacing frequency stabilization system for optical frequency-division-multiplexing communications is reported. Considering variable environmental condition and device aging effects, we have designed two loops in the system using a Fabry-perot interferometer as a frequency reference. One loop is a fine-tuning one, which is a time-division-multiplexing frequency stabilization scheme adjusting the driving currents of all the transmitter. The other loop is a rough-tuning one, which is a series of newly designed digital temperature controllers in which microprocessors and electrical oscillation circuits rather than Wheatstone bridge- circuits are used to detect the temperature error signal in order to reduce laser operating temperature dependence on the environmental conditions and there are RS-232 interfaces for communications with the first loop.

  14. Coherent THz Synchrotron Radiation from a Storage Ring with High-Frequency RF System

    SciTech Connect

    Wang, F.; Cheever, D.; Farkhondeh, M.; Franklin, W.; Ihloff, E.; Laan, J. van der; McAllister, B.; Milner, R.; Tschalaer, C.; Wang, D.; Wang, D.F.; Zolfaghari, A.; Zwart, T.; Carr, G.L.; Podobedov, B.; Sannibale, F.

    2006-02-17

    The generation of brilliant, stable, and broadband coherent synchrotron radiation (CSR) in electron storage rings depends strongly on ring rf system properties such as frequency and gap voltage. We have observed intense coherent radiation at frequencies approaching the THz regime produced by the MIT-Bates South Hall Ring, which employs a high-frequency S-band rf system. The measured CSR spectral intensity enhancement with 2 mA stored current was up to 10 000 times above background for wave numbers near 3 cm{sup -1}. The measurements also uncovered strong beam instabilities that must be suppressed if such a very high rf frequency electron storage ring is to become a viable coherent THz source.

  15. Coherent THz synchrotron radiation from a storage ring with high-frequency RF system.

    PubMed

    Wang, F; Cheever, D; Farkhondeh, M; Franklin, W; Ihloff, E; van der Laan, J; McAllister, B; Milner, R; Tschalaer, C; Wang, D; Wang, D F; Zolfaghari, A; Zwart, T; Carr, G L; Podobedov, B; Sannibale, F

    2006-02-17

    The generation of brilliant, stable, and broadband coherent synchrotron radiation (CSR) in electron storage rings depends strongly on ring rf system properties such as frequency and gap voltage. We have observed intense coherent radiation at frequencies approaching the THz regime produced by the MIT-Bates South Hall Ring, which employs a high-frequency S-band rf system. The measured CSR spectral intensity enhancement with 2 mA stored current was up to 10,000 times above background for wave numbers near 3 cm(-1). The measurements also uncovered strong beam instabilities that must be suppressed if such a very high rf frequency electron storage ring is to become a viable coherent THz source.

  16. Performance analysis of single-frequency MPPSK integrated system for ranging applications.

    PubMed

    Yao, Yu; Wu, Lenan

    2014-01-01

    The dual-frequency MPPSK-MODEM is a flexible platform. When ranging accuracy request is low or platform is particularly limited by power, the platform would perform both data transmission and range measurement with single-frequency modes. In this paper, the ranging resolution of MPPSK pulse waveforms with the match filter and impacting filter processing are discussed, respectively. Also, the parameter selection of MPPSK modulator for ranging is considered. In particular, requirements that allow for employing such special parameter values for range measurements with high accuracy and high range are investigated. Moreover, high repetition frequency (HRF) biphase code MPPSK pulse train base on m sequence is presented, and the ranging accuracy of the proposed signal with the match filter processing is deduced. In addition to theoretical considerations, the paper presents system simulations and measurement results of single-frequency MPPSK integrated systems, demonstrating the high-performance of ranging applications.

  17. Performance Analysis of Single-Frequency MPPSK Integrated System for Ranging Applications

    PubMed Central

    Wu, Lenan

    2014-01-01

    The dual-frequency MPPSK-MODEM is a flexible platform. When ranging accuracy request is low or platform is particularly limited by power, the platform would perform both data transmission and range measurement with single-frequency modes. In this paper, the ranging resolution of MPPSK pulse waveforms with the match filter and impacting filter processing are discussed, respectively. Also, the parameter selection of MPPSK modulator for ranging is considered. In particular, requirements that allow for employing such special parameter values for range measurements with high accuracy and high range are investigated. Moreover, high repetition frequency (HRF) biphase code MPPSK pulse train base on m sequence is presented, and the ranging accuracy of the proposed signal with the match filter processing is deduced. In addition to theoretical considerations, the paper presents system simulations and measurement results of single-frequency MPPSK integrated systems, demonstrating the high-performance of ranging applications. PMID:25140340

  18. Performance of a laser frequency comb calibration system with a high-resolution solar echelle spectrograph

    NASA Astrophysics Data System (ADS)

    Doerr, H.-P.; Kentischer, T. J.; Steinmetz, T.; Probst, R. A.; Franz, M.; Holzwarth, R.; Udem, Th.; Hänsch, T. W.; Schmidt, W.

    2012-09-01

    Laser frequency combs (LFC) provide a direct link between the radio frequency (RF) and the optical frequency regime. The comb-like spectrum of an LFC is formed by exact equidistant laser modes, whose absolute optical frequencies are controlled by RF-references such as atomic clocks or GPS receivers. While nowadays LFCs are routinely used in metrological and spectroscopic fields, their application in astronomy was delayed until recently when systems became available with a mode spacing and wavelength coverage suitable for calibration of astronomical spectrographs. We developed a LFC based calibration system for the high-resolution echelle spectrograph at the German Vacuum Tower Telescope (VTT), located at the Teide observatory, Tenerife, Canary Islands. To characterize the calibration performance of the instrument, we use an all-fiber setup where sunlight and calibration light are fed to the spectrograph by the same single-mode fiber, eliminating systematic effects related to variable grating illumination.

  19. Method of implementing frequency encoded multiplexer and demultiplexer systems using nonlinear semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Garai, Sisir Kumar; Mukhopadhyay, Sourangshu

    2009-11-01

    Multiplexing and demultiplexing are the essential parts of any communication network. In case of optical multiplexing and demultiplexing the coding of the data as well as the coding of control signals are most important issues. Many encoding/decoding mechanisms have already been developed in optical communication technology. Recently frequency encoding technique has drawn some special interest to the scientific communities. The advantage of frequency encoding technique over any other techniques is that as the frequency is fundamental character of any signal so it remains unaltered in reflection, refraction, absorption, etc. during transmission of the signal and therefore the system will execute the operation with reliability. On the other hand, the switching speed of semiconductor optical amplifiers (SOA) is sufficiently high with property of best on/off contrast ratio. In our present communication we propose a method of implementing a '4-to-1' multiplexer (MUX) and a '1-to-4' demultiplexer (DEMUX) exploiting the switching character of nonlinear SOA with the use of frequency encoded control signals. To implement the '4-to-1' MUX and '1-to-4' DEMUX system, the frequency selection by multiquantum well (MQW)-grating filter-based SOA has been used for frequency routing purpose. At the same time, the polarization rotation character of SOA has also been exploited to get the desired purpose. Here the fast switching action of SOA with reliable frequency encoded control input signals, it is possible to achieve a faithful MUX/DEMUX service at tera-Hz operational speed.

  20. Cross-Modulated Amplitudes and Frequencies Characterize Interacting Components in Complex Systems

    NASA Astrophysics Data System (ADS)

    Gans, Fabian; Schumann, Aicko Y.; Kantelhardt, Jan W.; Penzel, Thomas; Fietze, Ingo

    2009-03-01

    The dynamics of complex systems is characterized by oscillatory components on many time scales. To study the interactions between these components we analyze the cross modulation of their instantaneous amplitudes and frequencies, separating synchronous and antisynchronous modulation. We apply our novel technique to brain-wave oscillations in the human electroencephalogram and show that interactions between the α wave and the δ or β wave oscillators as well as spatial interactions can be quantified and related with physiological conditions (e.g., sleep stages). Our approach overcomes the limitation to oscillations with similar frequencies and enables us to quantify directly nonlinear effects such as positive or negative frequency modulation.