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Sample records for 12b-6 multi-frequency encoding

  1. A magnetization study of RCo 12B 6 intermetallics

    NASA Astrophysics Data System (ADS)

    Mittag, M.; Rosenberg, M.; Buschow, K. H. J.

    1989-11-01

    The magnetic properties of polycrystalline intermetallics RCo 12B 6 with R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm have been studied in the temperature range 3-300 K and in fields up to 2 T. All compounds order magnetically between Tc=134.3 K for CeCo 12B 6 and Tc=162 K for GdCo 12B 6. YCo 12B 6 has an average Co moment of 0.42μ B. Since the Co moment is constant for all samples the R moments can be easily obtained and they are in good agreement with free R 3+ ion values. Ce is quadripositive in CeCo 12B 6 and therefore nonmagnetic. All light rare-earth compounds are ferromagnetic, while all heavy rare-earth compounds are ferrimagnetic with compensation points between Tcomp=11.6 K ( TmCo12B6) and Tcomp=82.8 K ( TbCo12B6). In the paramagnetic state an effective magnetic moment of 1.94μ B per Co atom has been found. The mean-field approximation yields a 3d-3d exchange integral of {J CoCo}/{k B}=110 K . The 3d-4f exchange integral is much smaller and equal to about {J RCo}/{k B}=6 K .

  2. Inverse and normal magnetocaloric effects in LaFe12B6

    NASA Astrophysics Data System (ADS)

    Diop, L. V. B.; Isnard, O.

    2016-06-01

    Intrinsic magnetic properties and magnetocaloric effect were studied for LaFe12B6 itinerant-electron system, which presents an antiferromagnetic ground state below 36 K. For certain magnetic fields values, LaFe12B6 exhibits a sequence of two successive magnetic transitions: an antiferromagnetic-ferromagnetic (AFM-FM) transition at low temperature followed by a ferromagnetic-paramagnetic transition, leading to normal and inverse magnetocaloric effects, respectively. At finite temperatures, both antiferromagnetic (AFM) and paramagnetic states can be transformed into a ferromagnetic (FM) state via a field-induced metamagnetic transition accompanied with a huge magnetic hysteresis. Moreover, we reveal that, at low temperatures, the magnetization displays abrupt jumps across the first-order AFM-FM transition, giving rise to an unusual and unique staircase-like behavior. LaFe12B6 exhibits both normal magnetocaloric effect around the Curie temperature and large inverse magnetocaloric effect around the AFM-FM transition temperature; for μ0ΔH = 7 T, ΔSM is found to be -6.8 and 19 J kg-1 K-1 around 38 and 8 K, respectively.

  3. Spin reorientation and magnetic structure of HoCo12B6 ferrimagnetic compound

    NASA Astrophysics Data System (ADS)

    Diop, L. V. B.; Isnard, O.

    2015-01-01

    The magnetic phase diagram is determined by combining magnetization measurements, ac susceptibility and neutron diffraction. The crystal and magnetic structures are also investigated. The HoCo12B6 compound exhibits ferrimagnetic behavior below TC = 147 K. Two antiferromagnetically coupled sublattices cancel out at the compensation temperature TComp = 46 K. HoCo12B6 undergoes a spin reorientation transition at TSR = 76 K the easy magnetization axis changes from axial to basal plane upon heating. The magnitude of the magnetic moments and their orientation are described and discussed. It is revealed that HoCo12B6 compound exhibits a commensurate magnetic structure below TSR and an incommensurate one slightly above TSR. Significantly different magnetic moments have been observed on the two Co crystal sites, a very low magnetic moment of 0.14 μB being refined on the Co 18 g position. In addition, the second order crystal electric-field parameter A20 at the rare-earth site is determined. This result is discussed and used to explain the observed spin reorientation transition by a competition between the Co and Ho sublattice anisotropy.

  4. Ultrasharp magnetization steps in the antiferromagnetic itinerant-electron system LaF e12B6

    NASA Astrophysics Data System (ADS)

    Diop, L. V. B.; Isnard, O.; Rodríguez-Carvajal, J.

    2016-01-01

    The remarkable intrinsic magnetic properties of the LaF e12B6 compound have been studied by neutron powder diffraction (NPD) and magnetization measurements. The NPD measurement reveals that LaF e12B6 exhibits an antiferromagnetic (AFM) structure that can be described with a magnetic propagation vector of (¼, ¼, ¼) below TN. In the amplitude-modulated model used for the refinement, the Fe magnetic moments are confined to the a b plane with a maximum value of 0.43 μB at 1.5 K. It is shown that the AFM state can be transformed to a ferromagnetic (FM) state via a field-induced first-order transition accompanied with a huge magnetic hysteresis. The LaF e12B6 compound is not only the unique stable R F e12B6 phase, along the rare-earth R series but also presents unique magnetic behavior for a purely 3 d itinerant electron system, including particularly low ordering temperature TN=36 K , remarkably small Fe moment, unusual amplitude-modulated magnetic arrangement, and a multicritical point in the magnetic phase diagram. In addition, we reveal that at 2 K, the AFM-FM transition is abrupt, leading to a large increase of the Fe magnetic moment up to 1.55 μB ; the magnetization curve presents ultrasharp steps, giving rise to an unusual staircaselike behavior.

  5. Associations between Intake of Folate, Methionine, and Vitamins B-12, B-6 and Prostate Cancer Risk in American Veterans

    PubMed Central

    Vidal, Adriana C.; Grant, Delores J.; Williams, Christina D.; Masko, Elizabeth; Allott, Emma H.; Shuler, Kathryn; McPhail, Megan; Gaines, Alexis; Calloway, Elizabeth; Gerber, Leah; Chi, Jen-Tsan; Freedland, Stephen J.; Hoyo, Cathrine

    2012-01-01

    Prostate cancer (PC) is the second leading cause of cancer death in men. Recent reports suggest that excess of nutrients involved in the one-carbon metabolism pathway increases PC risk; however, empirical data are lacking. Veteran American men (272 controls and 144 PC cases) who attended the Durham Veteran American Medical Center between 2004–2009 were enrolled into a case-control study. Intake of folate, vitamin B12, B6, and methionine were measured using a food frequency questionnaire. Regression models were used to evaluate the association among one-carbon cycle nutrients, MTHFR genetic variants, and prostate cancer. Higher dietary methionine intake was associated with PC risk (OR = 2.1; 95%CI 1.1–3.9) The risk was most pronounced in men with Gleason sum <7 (OR = 2.75; 95%CI 1.32– 5.73). The association of higher methionine intake and PC risk was only apparent in men who carried at least one MTHFR A1298C allele (OR = 6.7; 95%CI = 1.6–27.8), compared to MTHFR A1298A noncarrier men (OR = 0.9; 95%CI = 0.24–3.92) (p-interaction = 0.045). There was no evidence for associations between B vitamins (folate, B12, and B6) and PC risk. Our results suggest that carrying the MTHFR A1298C variants modifies the association between high methionine intake and PC risk. Larger studies are required to validate these findings. PMID:22927849

  6. Multi-Frequency Band Pyroelectric Sensors

    PubMed Central

    Hsiao, Chun-Ching; Liu, Sheng-Yi

    2014-01-01

    A methodology is proposed for designing a multi-frequency band pyroelectric sensor which can detect subjects with various frequencies or velocities. A structure with dual pyroelectric layers, consisting of a thinner sputtered ZnO layer and a thicker aerosol ZnO layer, proved helpful in the development of the proposed sensor. The thinner sputtered ZnO layer with a small thermal capacity and a rapid response accomplishes a high-frequency sensing task, while the thicker aerosol ZnO layer with a large thermal capacity and a tardy response is responsible for low-frequency sensing tasks. A multi-frequency band pyroelectric sensor is successfully designed, analyzed and fabricated in the present study. The range of the multi-frequency sensing can be estimated by means of the proposed design and analysis to match the thicknesses of the sputtered and the aerosol ZnO layers. The fabricated multi-frequency band pyroelectric sensor with a 1 μm thick sputtered ZnO layer and a 20 μm thick aerosol ZnO layer can sense a frequency band from 4000 to 40,000 Hz without tardy response and low voltage responsivity. PMID:25429406

  7. Multi-Frequency Intravascular Ultrasound (IVUS) Imaging

    PubMed Central

    Ma, Teng; Yu, Mingyue; Chen, Zeyu; Fei, Chunlong; Shung, K. Kirk; Zhou, Qifa

    2015-01-01

    Acute coronary syndrome (ACS) is frequently associated with the sudden rupture of a vulnerable atherosclerotic plaque within the coronary artery. Several unique physiological features, including a thin fibrous cap accompanied by a necrotic lipid core, are the targeted indicators for identifying the vulnerable plaques. Intravascular ultrasound (IVUS), a catheter-based imaging technology, has been routinely performed in clinics for more than 20 years to describe the morphology of the coronary artery and guide percutaneous coronary interventions. However, conventional IVUS cannot facilitate the risk assessment of ACS because of its intrinsic limitations, such as insufficient resolution. Renovation of the IVUS technology is essentially needed to overcome the limitations and enhance the coronary artery characterization. In this paper, a multi-frequency intravascular ultrasound (IVUS) imaging system was developed by incorporating a higher frequency IVUS transducer (80 to 150 MHz) with the conventional IVUS (30–50 MHz) system. The newly developed system maintains the advantage of deeply penetrating imaging with the conventional IVUS, while offering an improved higher resolution image with IVUS at a higher frequency. The prototyped multi-frequency catheter has a clinically compatible size of 0.95 mm and a favorable capability of automated image co-registration. In vitro human coronary artery imaging has demonstrated the feasibility and superiority of the multi-frequency IVUS imaging system to deliver a more comprehensive visualization of the coronary artery. This ultrasonic-only intravascular imaging technique, based on a moderate refinement of the conventional IVUS system, is not only cost-effective from the perspective of manufacturing and clinical practice, but also holds the promise of future translation into clinical benefits. PMID:25585394

  8. 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.

  9. Inverse scattering problems with multi-frequencies

    NASA Astrophysics Data System (ADS)

    Bao, Gang; Li, Peijun; Lin, Junshan; Triki, Faouzi

    2015-09-01

    This paper is concerned with computational approaches and mathematical analysis for solving inverse scattering problems in the frequency domain. The problems arise in a diverse set of scientific areas with significant industrial, medical, and military applications. In addition to nonlinearity, there are two common difficulties associated with the inverse problems: ill-posedness and limited resolution (diffraction limit). Due to the diffraction limit, for a given frequency, only a low spatial frequency part of the desired parameter can be observed from measurements in the far field. The main idea developed here is that if the reconstruction is restricted to only the observable part, then the inversion will become stable. The challenging task is how to design stable numerical methods for solving these inverse scattering problems inspired by the diffraction limit. Recently, novel recursive linearization based algorithms have been presented in an attempt to answer the above question. These methods require multi-frequency scattering data and proceed via a continuation procedure with respect to the frequency from low to high. The objective of this paper is to give a brief review of these methods, their error estimates, and the related mathematical analysis. More attention is paid to the inverse medium and inverse source problems. Numerical experiments are included to illustrate the effectiveness of these methods.

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

    PubMed

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

    2006-01-01

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

  11. A Meliorated Multi-Frequency Band Pyroelectric Sensor.

    PubMed

    Hsiao, Chun-Ching; Liu, Sheng-Yi; Siao, An-Shen

    2015-01-01

    This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band. PMID:26153772

  12. A Meliorated Multi-Frequency Band Pyroelectric Sensor

    PubMed Central

    Hsiao, Chun-Ching; Liu, Sheng-Yi; Siao, An-Shen

    2015-01-01

    This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band. PMID:26153772

  13. Development of a wearable multi-frequency impedance cardiography device.

    PubMed

    Weyer, Sören; Menden, Tobias; Leicht, Lennart; Leonhardt, Steffen; Wartzek, Tobias

    2015-02-01

    Cardiovascular diseases as well as pulmonary oedema can be early diagnosed using vital signs and thoracic bio-impedance. By recording the electrocardiogram (ECG) and the impedance cardiogram (ICG), vital parameters are captured continuously. The aim of this study is the continuous monitoring of ECG and multi-frequency ICG by a mobile system. A mobile measuring system, based on 'low-power' ECG, ICG and an included radio transmission is described. Due to the high component integration, a board size of only 6.5 cm×5 cm could be realized. The measured data can be transmitted via Bluetooth and visualized on a portable monitor. By using energy-efficient hardware, the system can operate for up to 18 hs with a 3 V battery, continuously sending data via Bluetooth. Longer operating times can be realized by decreased transfer rates. The relative error of the impedance measurement was less than 1%. The ECG and ICG measurements allow an approximate calculation of the heart stroke volume. The ECG and the measured impedance showed a high correlation to commercial devices (r=0.83, p<0.05). In addition to commercial devices, the developed system allows a multi-frequency measurement of the thoracic impedance between 5-150 kHz. PMID:25559781

  14. 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.

  15. Multi-frequency fringe projection profilometry based on wavelet transform.

    PubMed

    Jiang, Chao; Jia, Shuhai; Dong, Jun; Lian, Qin; Li, Dichen

    2016-05-30

    Based on wavelet transforms (WTs), an alternative multi-frequency fringe projection profilometry is described. Fringe patterns with multiple frequencies are projected onto an object and the reflected patterns are recorded digitally. Phase information for every pattern is calculated by identifying the ridge that appears in WT results. Distinct from the phase unwrapping process, a peak searching algorithm is applied to obtain object height from the phases of the different frequency for a single point on the object. Thus, objects with large discontinuities can be profiled. In comparing methods, the height profiles obtained from the WTs have lower noise and higher measurement accuracy. Although measuring times are similar, the proposed method offers greater reliability. PMID:27410063

  16. Comparative Analyses Of Multi-Frequency PSI Ground Deformation Measurements

    NASA Astrophysics Data System (ADS)

    Duro, Javier; Sabater, Jose R.; Albiol, David; Koudogbo, Fifame N.; Arnaud, Alain

    2012-01-01

    In recent years many new developments have been made in the field of SAR image analysis. The wider diversity of available SAR imagery gives the possibility of covering wide ranges of applications in the domain of ground motion monitoring for risk management and damage assessment. The work proposed is based on the evaluation of differences in ground deformation measurements derived from multi-frequency PSI analyses. The objectives of the project are the derivation of rules and the definition of criteria for the selection of the appropriate SAR sensor for a particular type of region of interest. Key selection factors are the satellite characteristics (operating frequency, spatial resolution, and revisit time), the geographic localization of AOI, the land cover type and the extension of the monitoring period. All presented InSAR analyses have been performed using the Stable Point Network (SPN) PSI software developed by Altamira Information [1].

  17. Acoustic metamaterial structures based on multi-frequency vibration absorbers

    NASA Astrophysics Data System (ADS)

    Pai, P. Frank; Peng, Hao

    2014-03-01

    This paper presents a new metamaterial beam based on multi-frequency vibration absorbers for broadband vibration absorption. The proposed metamaterial beam consists of a uniform isotropic beam and small two-mass spring-mass- damper subsystems at many locations along the beam to act as multi-frequency vibration absorbers. For an infinite metamaterial beam, governing equations of a unit cell are derived using the extended Hamilton principle. The existence of two stopbands is demonstrated using a model based on averaging material properties over a cell length and a model based on finite element modeling and the Bloch-Floquet theory for periodic structures. For a finite metamaterial beam, because these two idealized models cannot be used for finite beams and/or elastic waves having short wavelengths, a finite-element method is used for detailed modeling and analysis. The concepts of negative effective mass and effective stiffness and how the spring-mass-damper subsystem creates two stopbands are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed metamaterial beam is based on the concept of conventional mechanical vibration absorbers. For an incoming wave with a frequency in one of the two stopbands, the absorbers are excited to vibrate in their optical modes to create shear forces to straighten the beam and stop the wave propagation. For an incoming wave with a frequency outside of but between the two stopbands, it can be efficiently damped out by the damper with the second mass of each absorber. Hence, the two stopbands are connected into a wide stopband. Numerical examples validate the concept and show that the structure's boundary conditions do not have significant influence on the absorption of high-frequency waves. However, for absorption of low-frequency waves, the structure's boundary conditions and resonance frequencies and the location and spatial distribution of absorbers need to be considered in design, and it

  18. Multi-frequency metal detector in high mineralization

    NASA Astrophysics Data System (ADS)

    Stamatescu, Laurence; Harmer, Gregory; Nesper, Oliver; Bordean, Dorin; Tkachenko, Yuri

    2009-05-01

    The successful detection and discrimination of mines is very difficult in areas of high soil mineralization. In these areas, the soil can make a significant contribution to the received signal that causes false detections or masks the true mine response. To address this problem, Minelab has developed a continuous wave (CW) multi-frequency digital detector (MFDD). It transmits four frequencies (between 1 kHz and 45 kHz) and each has a high dynamic range that approaches 120 dB. The mineralized soil with high magnetic susceptibility affects the characteristics of the sensor-head, in particular the inductance of the transmitting and receiving windings. These in turn affect the front-end electronics and measuring circuits and can lead to excessive ground noise that makes detection difficult. Minelab has modeled the effect that the soil has on the sensor-head and developed methods to monitor these effects. By having a well calibrated detector, which is demonstrated by the tight agreement of raw ground signals with theoretical ground models, the tasks of ground balance and discrimination become much more reliable and robust.

  19. Multi-frequency bioimpedance in human muscle assessment

    PubMed Central

    Bartels, Else Marie; Sørensen, Emma Rudbæk; Harrison, Adrian Paul

    2015-01-01

    Bioimpedance analysis (BIA) is a well-known and tested method for body mass and muscular health assessment. Multi-frequency BIA (mfBIA) equipment now makes it possible to assess a particular muscle as a whole, as well as looking at a muscle at the fiber level. The aim of this study was to test the hypothesis that mfBIA can be used to assess the anatomical, physiological, and metabolic state of skeletal muscles. mfBIA measurements focusing on impedance, resistance, reactance, phase angle, center frequency, membrane capacitance, and both extracellular and intracellular resistance were carried out. Eight healthy human control subjects and three selected cases were examined to demonstrate the extent to which this method may be used clinically, and in relation to training in sport. The electrode setup is shown to affect the mfBIA parameters recorded. Our recommendation is the use of noble metal electrodes in connection with a conductance paste to accommodate the typical BIA frequencies, and to facilitate accurate impedance and resistance measurements. The use of mfBIA parameters, often in conjunction with each other, can be used to reveal indications of contralateral muscle loss, extracellular fluid differences, contracted state, and cell transport/metabolic activity, which relate to muscle performance. Our findings indicate that mfBIA provides a noninvasive, easily measurable and very precise momentary assessment of skeletal muscles. PMID:25896978

  20. Error control coding for multi-frequency modulation

    NASA Astrophysics Data System (ADS)

    Ives, Robert W.

    1990-06-01

    Multi-frequency modulation (MFM) has been developed at NPS using both quadrature-phase-shift-keyed (QPSK) and quadrature-amplitude-modulated (QAM) signals with good bit error performance at reasonable signal-to-noise ratios. Improved performance can be achieved by the introduction of error control coding. This report documents a FORTRAN simulation of the implementation of error control coding into an MFM communication link with additive white Gaussian noise. Four Reed-Solomon codes were incorporated, two for 16-QAM and two for 32-QAM modulation schemes. The error control codes used were modified from the conventional Reed-Solomon codes in that one information symbol was sacrificed to parity in order to use a simplified decoding algorithm which requires no iteration and enhances error detection capability. Bit error rates as a function of SNR and E(sub b)/N(sub 0) were analyzed, and bit error performance was weighed against reduction in information rate to determine the value of the codes.

  1. Multi-frequency bioimpedance in equine muscle assessment.

    PubMed

    Harrison, Adrian Paul; Elbrønd, Vibeke Sødring; Riis-Olesen, Kiwa; Bartels, Else Marie

    2015-03-01

    Multi-frequency BIA (mfBIA) equipment has been shown to be a non-invasive and reliable method to assess a muscle as a whole or at fibre level. In the equine world this may be the future method of assessment of training condition or of muscle injury. The aim of this study was to test if mfBIA reliably can be used to assess the condition of a horse's muscles in connection with health assessment, injury and both training and re-training. mfBIA measurements was carried out on 10 'hobby' horses and 5 selected cases with known anamnesis. Impedance, resistance, reactance, phase angle, centre frequency, membrane capacitance and both extracellular and intracellular resistance were measured. Platinum electrodes in connection with a conductance paste were used to accommodate the typical BIA frequencies and to facilitate accurate measurements. Use of mfBIA data to look into the effects of myofascial release treatment was also demonstrated. Our findings indicate that mfBIA provides a non-invasive, easily measurable and very precise assessment of the state of muscles in horses. This study also shows the potential of mfBIA as a diagnostic tool as well as a tool to monitor effects of treatment e.g. myofascial release therapy and metabolic diseases, respectively. PMID:25656988

  2. The status of the QUIJOTE multi-frequency instrument

    NASA Astrophysics Data System (ADS)

    Hoyland, R. J.; Aguiar-González, M.; Aja, B.; Ariño, J.; Artal, E.; Barreiro, R. B.; Blackhurst, E. J.; Cagigas, J.; Cano de Diego, J. L.; Casas, F. J.; Davis, R. J.; Dickinson, C.; Arriaga, B. E.; Fernandez-Cobos, R.; de la Fuente, L.; Génova-Santos, R.; Gómez, A.; Gomez, C.; Gómez-Reñasco, F.; Grainge, K.; Harper, S.; Herran, D.; Herreros, J. M.; Herrera, G. A.; Hobson, M. P.; Lasenby, A. N.; Lopez-Caniego, M.; López-Caraballo, C.; Maffei, B.; Martinez-Gonzalez, E.; McCulloch, M.; Melhuish, S.; Mediavilla, A.; Murga, G.; Ortiz, D.; Piccirillo, L.; Pisano, G.; Rebolo-López, R.; Rubiño-Martin, J. A.; Ruiz, J. Luis; Sanchez de la Rosa, V.; Sanquirce, R.; Vega-Moreno, A.; Vielva, P.; Viera-Curbelo, T.; Villa, E.; Vizcargüenaga, A.; Watson, R. A.

    2012-09-01

    The QUIJOTE-CMB project has been described in previous publications. Here we present the current status of the QUIJOTE multi-frequency instrument (MFI) with five separate polarimeters (providing 5 independent sky pixels): two which operate at 10-14 GHz, two which operate at 16-20 GHz, and a central polarimeter at 30 GHz. The optical arrangement includes 5 conical corrugated feedhorns staring into a dual reflector crossed-draconian system, which provides optimal cross-polarization properties (designed to be < -35 dB) and symmetric beams. Each horn feeds a novel cryogenic on-axis rotating polar modulator which can rotate at a speed of up to 1 Hz. The science driver for this first instrument is the characterization of the galactic emission. The polarimeters use the polar modulator to derive linear polar parameters Q, U and I and switch out various systematics. The detection system provides optimum sensitivity through 2 correlated and 2 total power channels. The system is calibrated using bright polarized celestial sources and through a secondary calibration source and antenna. The acquisition system, telescope control and housekeeping are all linked through a real-time gigabit Ethernet network. All communication, power and helium gas are passed through a central rotary joint. The time stamp is synchronized to a GPS time signal. The acquisition software is based on PLCs written in Beckhoffs TwinCat and ethercat. The user interface is written in LABVIEW. The status of the QUIJOTE MFI will be presented including pre-commissioning results and laboratory testing.

  3. Exploration Depth of Multi-frequency Helicopter EM Systems

    NASA Astrophysics Data System (ADS)

    Yin, C.; Hodges, G.

    2004-05-01

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

  4. Effect of randomness on multi-frequency aeroelastic responses resolved by Unsteady Adaptive Stochastic Finite Elements

    SciTech Connect

    Witteveen, Jeroen A.S. Bijl, Hester

    2009-10-01

    The Unsteady Adaptive Stochastic Finite Elements (UASFE) method resolves the effect of randomness in numerical simulations of single-mode aeroelastic responses with a constant accuracy in time for a constant number of samples. In this paper, the UASFE framework is extended to multi-frequency responses and continuous structures by employing a wavelet decomposition pre-processing step to decompose the sampled multi-frequency signals into single-frequency components. The effect of the randomness on the multi-frequency response is then obtained by summing the results of the UASFE interpolation at constant phase for the different frequency components. Results for multi-frequency responses and continuous structures show a three orders of magnitude reduction of computational costs compared to crude Monte Carlo simulations in a harmonically forced oscillator, a flutter panel problem, and the three-dimensional transonic AGARD 445.6 wing aeroelastic benchmark subject to random fields and random parameters with various probability distributions.

  5. Sparse reconstruction for direction-of-arrival estimation using multi-frequency co-prime arrays

    NASA Astrophysics Data System (ADS)

    BouDaher, Elie; Ahmad, Fauzia; Amin, Moeness G.

    2014-12-01

    In this paper, multi-frequency co-prime arrays are employed to perform direction-of-arrival (DOA) estimation with enhanced degrees of freedom (DOFs). Operation at multiple frequencies creates additional virtual elements in the difference co-array of the co-prime array corresponding to the reference frequency. Sparse reconstruction is then used to fully exploit the enhanced DOFs offered by the multi-frequency co-array, thereby increasing the number of resolvable sources. For the case where the sources have proportional spectra, the received signal vectors at the different frequencies are combined to form an equivalent single measurement vector model corresponding to the multi-frequency co-array. When the sources have nonproportional spectra, a group sparsity-based reconstruction approach is used to determine the direction of signal arrivals. Performance evaluation of the proposed multi-frequency approach is performed using numerical simulations for both cases of proportional and nonproportional source spectra.

  6. Application of global phase filtering method in multi frequency measurement.

    PubMed

    Song, Limei; Chang, Yulan; Li, Zongyan; Wang, Pengqiang; Xing, Guangxin; Xi, Jiangtao

    2014-06-01

    In reverse engineering, reconstruction of 3D point cloud data is the key step to acquire the final profile of the object. However, the quality of 3D reconstruction is influenced by noise in the three-dimensional measurement. This paper aims to tackle the issue of removing the noisy data from the complex point cloud data. The 3D-GPF (Three Dimensional Global Phase Filtering) global phase filtering method is proposed based on the study of phase filtering method, consisting of the steps below. Firstly, the six-step phase shift profilometry is used to obtain the local phase information, and encoding the obtained phase information. Through the global phase unwrapping method, the global phase can be acquired. Secondly, 3D-GPF method is used for the obtained global phase. Finally, the effect of 3D reconstruction is analyzed after the global phase filtering. Experimental results indicate that the noisy points of three-dimensional graphics is reduced 98.02%, the speed of 3D reconstruction is raised 12%.The effect of the proposed global phase filtering method is better than DCT and GSM methods. It is high precision and fast speed, and can be widely used in other 3D reconstruction application. PMID:24921558

  7. Multi-Frequency Soliton Complex in Er/Yb-Doped Fiber Amplifier

    NASA Technical Reports Server (NTRS)

    Kang, Jin U.; Kim, Do-Hyun; Khurgin, Jacob B.; Akhmediev, Nail N.; Han, Haewook; Shaw, Harry; Day, John H. (Technical Monitor)

    2001-01-01

    We experimentally investigated presence of multi-frequency soliton complex that exist in high power Er/Yb-doped Fiber Amplifier. The complex with the spectral bandwidth in excess of 100 nm is bound by the Kerr nonlinearity and exhibit stable propagation.

  8. Noise Suppression and Enhanced Focusability in Plasma Raman Amplifier with Multi-frequency Pump

    SciTech Connect

    A.A. Balakin; G.M. Fraiman; N.J. Fisch; V.M. Malkin

    2003-06-16

    Laser pulse compression/amplification through Raman backscattering in plasmas can be facilitated by using multi-frequency pump laser beams. The efficiency of amplification is increased by suppressing the Raman instability of thermal fluctuations and seed precursors. Also the focusability of the amplified radiation is enhanced due to the suppression of large-scale longitudinal speckles in the pump wave structure.

  9. OCT based on multi-frequency sweeping Fizeau interferometer with phase modulating method

    NASA Astrophysics Data System (ADS)

    Choi, S.; Watanabe, T.; Sasaki, O.; Suzuki, T.

    2013-09-01

    The Multi-frequency sweeping Fizeau-type interferometer (MFS-FI) for optical coherence tomography (OCT) is demonstrated. The multi-frequency sweeping by a variable Fabry-Perot filter permits detection of high-order low-coherence interferometric signals in the Fizeau interferometer. The sinusoidal phase modulation technique was utilized to detect accurate interference amplitude and phase distributions of back scattered light from surfaces of a sample. OCT measurements by the MFS-FI were conducted for vibrating glass plates with a frequency of 1 kHz, and cellular tissues fixed with formalin and embedded in paraffin. The tomographic 3-dimensional volume and cross-sectional surface displacements were detected with an accuracy of nano-meters.

  10. Multi-frequency phase-coded microwave signal generation based on polarization modulation and balanced detection.

    PubMed

    Zhu, Dan; Xu, Weiyuan; Wei, Zhengwu; Pan, Shilong

    2016-01-01

    Photonic multi-frequency phase-coded microwave signal generation is proposed and demonstrated based on polarization modulation and balanced detection. Consisting of only a polarization modulator (PolM) driven by an electrical coding data, a polarization beam splitter (PBS) and a balanced photodetector (BPD), the proposed microwave phase coder has no requirement on the wavelength, intensity modulation format, or modulation index of the input optical microwave signal, and allows phase coding of arbitrary-format RF signals, which enables multi-frequency phase coding with compact structure, simple operation, and high flexibility. A proof-of-concept experiment is performed, achieving simultaneous phase coding of 15 and 30 GHz, or 10 and 20 GHz RF signals with a coding rate of 5  Gb/s. PMID:26696170

  11. A 3D tunable and multi-frequency graphene plasmonic cloak.

    PubMed

    Farhat, Mohamed; Rockstuhl, Carsten; Bağcı, Hakan

    2013-05-20

    We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers are doped via a variable external voltage difference permitting continuous tuning of the cloaking frequencies. Particularly, two configurations are investigated: (i) Only one graphene layer is used to suppress the scattering from a dielectric sphere. (ii) Several of these layers biased at different gate voltages are used to achieve a multi-frequency cloak. These frequencies can be set independently. The proposed cloak's functionality is verified by near- and far-field computations. By considering geometry and material parameters that are realizable by practical experiments, we contribute to the development of graphene based plasmonic applications that may find use in disruptive photonic technologies. PMID:23736478

  12. Simultaneous reconstruction of permittivity and conductivity using multi-frequency admittance measurement in electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Maomao; Soleimani, Manuchehr

    2016-02-01

    Electrical capacitance tomography (ECT) is an imaging method mainly capable of reconstructing dielectric permittivity. Generally, the reactance part of complex admittance is measured in a selected frequency. This paper presents for the first time an in depth and systematic analysis of complex admittance data for simultaneous reconstruction of both electrical conductivity and dielectric permittivity. A complex-valued forward model, Jacobian matrix and inverse solution are developed in the time harmonic excitation mode to allow for multi-frequency measurements. Realistic noise models are used to evaluate the performance of complex admittance ECT in a range of excitation frequencies. This paper demonstrates far greater potential for ECT as a versatile imaging tool through novel analysis of complex admittance imaging using a dual conductivity permittivity inversion method. The paper demonstrates that various classes of contactless capacitance based measurement devices can be analysed through complex multi-frequency ECT.

  13. Multi-frequency properties of an narrow angle tail radio galaxy J 0037+18

    NASA Astrophysics Data System (ADS)

    Patra, Dusmanta; Chakrabarti, Sandip Kumar; Pal, Sabyasachi; Konar, Chiranjib

    2016-07-01

    We will present multi-frequency properties of narrow angle tailed radio galaxy J 0037+18 using data from Giant Metrewave Radio Telescope (GMRT) and Jansky Very Large Array (JVLA). The angle between two lobes is only 38 degree. We will discuss magnetic field and particle life time of the jet. Spectral properties of the source will be discussed. We also used optical and X-ray data to investigate host environment.

  14. J16021+3326: NEW MULTI-FREQUENCY OBSERVATIONS OF A COMPLEX SOURCE

    SciTech Connect

    Tremblay, S. E.; Taylor, G. B.; Richards, J. L.; Readhead, A. C. S.; Helmboldt, J. F.; Romani, R. W.; Healey, S. E.

    2010-03-20

    We present multi-frequency Very Long Baseline Array observations of J16021+3326. These observations, along with variability data obtained from the Owens Valley Radio Observatory candidate gamma-ray blazar monitoring program, clearly indicate that this source is a blazar. The peculiar characteristic of this blazar, which daunted previous classification attempts, is that we appear to be observing down a precessing jet, the mean orientation of which is aligned with us almost exactly.

  15. RATAN-600 multi-frequency data for the BL Lacertae objects

    NASA Astrophysics Data System (ADS)

    Mingaliev, M. G.; Sotnikova, Yu. V.; Udovitskiy, R. Yu.; Mufakharov, T. V.; Nieppola, E.; Erkenov, A. K.

    2014-12-01

    Aims: We present a new catalogue of the RATAN-600 multi-frequency measurements for BL Lac objects. The purpose of this catalogue is to compile the BL Lac multi-frequency data that is acquired with the RATAN-600 simultaneously at several frequencies. The BL Lac objects emit a strongly variable and polarized non-thermal radiation across the entire electromagnetic spectrum from radio to γ rays and represent about 1% of known AGNs. They belong to the blazar population and differ from other blazars' featureless optical spectrum, which sometimes have absorption lines, or have weak and narrow emission lines. One of the most effective ways of studying the physics of BL Lacs is the use of simultaneous multi-frequency data. Methods: The multi-frequency broadband radio spectrum was obtained simultaneously with an accuracy of up to 1-2 min for four to six frequencies: 1.1, 2.3, 4.8, 7.7, 11.2, and 21.7 GHz. The catalogue is based on the RATAN-600 observations and on the data from: equatorial coordinate and redshift, R-band magnitude, synchrotron peak frequency, SED classes, and object type literature. Results: The present version of the catalogue contains RATAN-600 flux densities measurements over nine years (2006-2014), radio spectra at different epochs, and their parameters of the catalogue for more than 300 BL Lacs objects and candidates. The BL Lacs list is constantly updated with new observational data of RATAN-600. The catalogue is presented in interactive form and available at Special Astrophysical Observatory of the Russian Academy of Sciences website http://www.sao.ru/blcat/

  16. Reconstruction of Flaw Profiles Using Neural Networks and Multi-Frequency Eddy Current System

    SciTech Connect

    Chady, T.; Caryk, M.

    2005-04-09

    The objective of this paper is to identify profiles of flaws in conducting plates. To solve this problem, application of a multi-frequency eddy current system (MFES) and artificial neural networks is proposed. Dynamic feed-forward neural networks with various architectures are investigated. Extended experiments with all neural models are carried out in order to select the most promising configuration. Data utilized for the experiments were obtained from the measurements performed on the Inconel plates with EDM flaws.

  17. Classifying multi-frequency fisheries acoustic data using a robust probabilistic classification technique.

    PubMed

    Anderson, C I H; Horne, J K; Boyle, J

    2007-06-01

    A robust probabilistic classification technique, using expectation maximization of finite mixture models, is used to analyze multi-frequency fisheries acoustic data. The number of clusters is chosen using the Bayesian Information Criterion. Probabilities of membership to clusters are used to classify each sample. The utility of the technique is demonstrated using two examples: the Gulf of Alaska representing a low-diversity, well-known system; and the Mid-Atlantic Ridge, a species-rich, relatively unknown system. PMID:17552574

  18. Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity

    USGS Publications Warehouse

    Brosten, T.R.; Day-Lewis, F. D.; Schultz, G.M.; Curtis, G.P.; Lane, J.W.

    2011-01-01

    Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita, Colorado, USA, are inverted to produce vertical distribution of electrical conductivity (EC) across the site. The relation between measured apparent electrical conductivity (ECa) and hydraulic conductivity (K) is weak (correlation coefficient of 0.20), whereas the correlation between the depth dependent EC obtained from the inversions, and K is sufficiently strong to be used for hydrologic estimation (correlation coefficient of -0.62). Depth-specific EC values were correlated with co-located K measurements to develop a site-specific ln(EC)-ln(K) relation. This petrophysical relation was applied to produce a spatially detailed map of K across the study area. A synthetic example based on ECa values at the site was used to assess model resolution and correlation loss given variations in depth and/or measurement error. Results from synthetic modeling indicate that optimum correlation with K occurs at ~0.5m followed by a gradual correlation loss of 90% at 2.3m. These results are consistent with an analysis of depth of investigation (DOI) given the range of frequencies, transmitter-receiver separation, and measurement errors for the field data. DOIs were estimated at 2.0??0.5m depending on the soil conductivities. A 4-layer model, with varying thicknesses, was used to invert the ECa to maximize available information within the aquifer region for improved correlations with K. Results show improved correlation between K and the corresponding inverted EC at similar depths, underscoring the importance of inversion in using multi-frequency EMI data for hydrologic estimation. ?? 2011.

  19. Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity

    NASA Astrophysics Data System (ADS)

    Brosten, Troy R.; Day-Lewis, Frederick D.; Schultz, Gregory M.; Curtis, Gary P.; Lane, John W., Jr.

    2011-04-01

    Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita, Colorado, USA, are inverted to produce vertical distribution of electrical conductivity ( EC) across the site. The relation between measured apparent electrical conductivity ( ECa) and hydraulic conductivity ( K) is weak (correlation coefficient of 0.20), whereas the correlation between the depth dependent EC obtained from the inversions, and K is sufficiently strong to be used for hydrologic estimation (correlation coefficient of - 0.62). Depth-specific EC values were correlated with co-located K measurements to develop a site-specific ln( EC)-ln( K) relation. This petrophysical relation was applied to produce a spatially detailed map of K across the study area. A synthetic example based on ECa values at the site was used to assess model resolution and correlation loss given variations in depth and/or measurement error. Results from synthetic modeling indicate that optimum correlation with K occurs at ~ 0.5 m followed by a gradual correlation loss of 90% at 2.3 m. These results are consistent with an analysis of depth of investigation (DOI) given the range of frequencies, transmitter-receiver separation, and measurement errors for the field data. DOIs were estimated at 2.0 ± 0.5 m depending on the soil conductivities. A 4-layer model, with varying thicknesses, was used to invert the ECa to maximize available information within the aquifer region for improved correlations with K. Results show improved correlation between K and the corresponding inverted EC at similar depths, underscoring the importance of inversion in using multi-frequency EMI data for hydrologic estimation.

  20. A Multi-frequency Beam-forming HF Radar for Tsunami Detection

    NASA Astrophysics Data System (ADS)

    Trizna, D. B.

    2007-05-01

    We discuss a new multi-frequency beam-forming HF radar design for robust detection and tracking of tsunami waves from 200 km distances, providing continuous coverage of the tsunami wave pattern after it impinges on the continental shelf. The method works by mapping ocean currents at long range using traditional HF radar method of radial Bragg line Doppler shift measurements. The tsunami is detected by anomalous spatial patterns of higher than normal Bragg-line shifts due to the large orbital wave of the series of tsunami wave crests as they impinge on the continental shelf. An approach using beam forming of 16 or 32 antenna elements provides an update every five minutes or less, while Direction-of-Arrival method systems using just a few antenna elements inherently require of the order of 30 to 60 minutes for a reliable current map. The multi-frequency radar provides a more robust capability than the single frequency HF radar for at least two reasons. First, because the HF channel user spectrum suffers diurnal variability in channel occupancy due to the ionosphere changing with time of day, low frequencies can become contaminated with user noise, so that maximum range for reliable detection not achieved. Under this condition, one would rely on quiet higher HF frequencies that lie above the Maximum Usable Frequency (MUF) for ionospheric reflection propagation. Alternatively, for daylight operation when low frequency utilization can be used to minimize surface wave propagation loss, the sea state might not be sufficiently active to allow long range coverage needed for reliable detection, due to the lack of ocean wave spectral energy at the Bragg-resonant wave frequency. Thus, single- frequency radars, operating in the 4-6 MHz range to minimize propagation losses to achieve long-range coverage, would suffer due to low wind conditions. The multi-frequency HF radar discussed here allows one to dynamically choose the optimum frequency from a set of 8 to 16, as allowed by

  1. Measuring two-phase particle flux with a multi-frequency acoustic Doppler profiler.

    PubMed

    Wilson, Gregory W; Hay, Alex E

    2015-12-01

    A methodology is developed and tested for simultaneously extracting time-resolved one-dimensional profiles of the mass-concentration and velocity of two different particle types in a mixed suspension, using a multi-frequency pulse-to-pulse coherent Doppler instrument. The technique involves inversion of a model for frequency-dependent acoustic backscatter amplitude and phase. Results are presented from a laboratory settling column experiment, measuring a mixture of polystyrene beads (slowly-settling, strongly-scattering) and glass beads (quickly-settling, weakly-scattering) in a vertical pipe section. PMID:26723335

  2. Multi-frequency study of jet in HH 80-81

    NASA Astrophysics Data System (ADS)

    Pal, Sabyasachi; Chakrabarti, Sandip Kumar; Patra, Dusmanta

    2016-07-01

    We present multi-wavelength radio observation of the large radio jet from Herbig-Halo object HH 80-81 to study morphology of the jet in detail. We have combined the low frequency data of Giant Metrewave Radio Telescope (GMRT) with high frequency Jansky Very Large Array (JVLA) archival data for multi-frequency study. We have seen a highly collimated jet emitting from central source and the jet is collinear with the central source and HH 80-81. The spectrum of the source is studied in detail and we find the signature of spectral absorption towards the low frequency region.

  3. Multi-frequency and edge localized modes in mechanical and electrical lattices

    NASA Astrophysics Data System (ADS)

    English, Lars; Palmero, Faustino; Kevrekidis, Panayotis

    We present experimental evidence for the existence of a type of dynamical, self-localized mode called a multi-frequency breather in both a mechanical lattice of pendula and an electrical lattice. These modes were excited and stabilized by subharmonic driving. We also experimentally characterize dynamical modes that are localized on the edges of the pendulum chain, as well as in 2D electrical lattices. In the latter system, we briefly discuss the role of lattice topology in the stability of such modes.

  4. TeraSCREEN: multi-frequency multi-mode Terahertz screening for border checks

    NASA Astrophysics Data System (ADS)

    Alexander, Naomi E.; Alderman, Byron; Allona, Fernando; Frijlink, Peter; Gonzalo, Ramón; Hägelen, Manfred; Ibáñez, Asier; Krozer, Viktor; Langford, Marian L.; Limiti, Ernesto; Platt, Duncan; Schikora, Marek; Wang, Hui; Weber, Marc Andree

    2014-06-01

    The challenge for any security screening system is to identify potentially harmful objects such as weapons and explosives concealed under clothing. Classical border and security checkpoints are no longer capable of fulfilling the demands of today's ever growing security requirements, especially with respect to the high throughput generally required which entails a high detection rate of threat material and a low false alarm rate. TeraSCREEN proposes to develop an innovative concept of multi-frequency multi-mode Terahertz and millimeter-wave detection with new automatic detection and classification functionalities. The system developed will demonstrate, at a live control point, the safe automatic detection and classification of objects concealed under clothing, whilst respecting privacy and increasing current throughput rates. This innovative screening system will combine multi-frequency, multi-mode images taken by passive and active subsystems which will scan the subjects and obtain complementary spatial and spectral information, thus allowing for automatic threat recognition. The TeraSCREEN project, which will run from 2013 to 2016, has received funding from the European Union's Seventh Framework Programme under the Security Call. This paper will describe the project objectives and approach.

  5. The Effect of Subcutaneous Fat on Electrical Impedance Myography: Electrode Configuration and Multi-Frequency Analyses.

    PubMed

    Li, Le; Li, Xiaoyan; Hu, Huijing; Shin, Henry; Zhou, Ping

    2016-01-01

    This study investigates the impact of the subcutaneous fat layer (SFL) thickness on localized electrical impedance myography (EIM), as well as the effects of different current electrodes, varying in distance and direction, on EIM output. Twenty-three healthy subjects underwent localized multi-frequency EIM on their biceps brachii muscles with a hand-held electrode array. The EIM measurements were recorded under three different configurations: wide (or outer) longitudinal configuration 6.8 cm, narrow (or inner) longitudinal configuration 4.5 cm, and narrow transverse configuration 4.5 cm. Ultrasound was applied to measure the SFL thickness. Coefficients of determination (R2) of three EIM variables (resistance, reactance, and phase) and SFL thickness were calculated. For the longitudinal configuration, the wide distance could reduce the effects of the subcutaneous fat when compared with the narrow distance, but a significant correlation still remained for all three EIM parameters. However, there was no significant correlation between SFL thickness and reactance in the transverse configuration (R2 = 0.0294, p = 0.434). Utilizing a ratio of 50kHz/100kHz phase was found to be able to help reduce the correlation with SFL thickness for all the three configurations. The findings indicate that the appropriate selection of the current electrode distance, direction and the multi-frequency phase ratio can reduce the impact of subcutaneous fat on EIM. These settings should be evaluated for future clinical studies using hand-held localized arrays to perform EIM. PMID:27227876

  6. Multi-frequency complex network from time series for uncovering oil-water flow structure

    PubMed Central

    Gao, Zhong-Ke; Yang, Yu-Xuan; Fang, Peng-Cheng; Jin, Ning-De; Xia, Cheng-Yi; Hu, Li-Dan

    2015-01-01

    Uncovering complex oil-water flow structure represents a challenge in diverse scientific disciplines. This challenge stimulates us to develop a new distributed conductance sensor for measuring local flow signals at different positions and then propose a novel approach based on multi-frequency complex network to uncover the flow structures from experimental multivariate measurements. In particular, based on the Fast Fourier transform, we demonstrate how to derive multi-frequency complex network from multivariate time series. We construct complex networks at different frequencies and then detect community structures. Our results indicate that the community structures faithfully represent the structural features of oil-water flow patterns. Furthermore, we investigate the network statistic at different frequencies for each derived network and find that the frequency clustering coefficient enables to uncover the evolution of flow patterns and yield deep insights into the formation of flow structures. Current results present a first step towards a network visualization of complex flow patterns from a community structure perspective. PMID:25649900

  7. 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.

  8. The Effect of Subcutaneous Fat on Electrical Impedance Myography: Electrode Configuration and Multi-Frequency Analyses

    PubMed Central

    Li, Le; Li, Xiaoyan; Hu, Huijing; Shin, Henry

    2016-01-01

    This study investigates the impact of the subcutaneous fat layer (SFL) thickness on localized electrical impedance myography (EIM), as well as the effects of different current electrodes, varying in distance and direction, on EIM output. Twenty-three healthy subjects underwent localized multi-frequency EIM on their biceps brachii muscles with a hand-held electrode array. The EIM measurements were recorded under three different configurations: wide (or outer) longitudinal configuration 6.8 cm, narrow (or inner) longitudinal configuration 4.5 cm, and narrow transverse configuration 4.5 cm. Ultrasound was applied to measure the SFL thickness. Coefficients of determination (R2) of three EIM variables (resistance, reactance, and phase) and SFL thickness were calculated. For the longitudinal configuration, the wide distance could reduce the effects of the subcutaneous fat when compared with the narrow distance, but a significant correlation still remained for all three EIM parameters. However, there was no significant correlation between SFL thickness and reactance in the transverse configuration (R2 = 0.0294, p = 0.434). Utilizing a ratio of 50kHz/100kHz phase was found to be able to help reduce the correlation with SFL thickness for all the three configurations. The findings indicate that the appropriate selection of the current electrode distance, direction and the multi-frequency phase ratio can reduce the impact of subcutaneous fat on EIM. These settings should be evaluated for future clinical studies using hand-held localized arrays to perform EIM. PMID:27227876

  9. Multi-frequency complex network from time series for uncovering oil-water flow structure

    NASA Astrophysics Data System (ADS)

    Gao, Zhong-Ke; Yang, Yu-Xuan; Fang, Peng-Cheng; Jin, Ning-De; Xia, Cheng-Yi; Hu, Li-Dan

    2015-02-01

    Uncovering complex oil-water flow structure represents a challenge in diverse scientific disciplines. This challenge stimulates us to develop a new distributed conductance sensor for measuring local flow signals at different positions and then propose a novel approach based on multi-frequency complex network to uncover the flow structures from experimental multivariate measurements. In particular, based on the Fast Fourier transform, we demonstrate how to derive multi-frequency complex network from multivariate time series. We construct complex networks at different frequencies and then detect community structures. Our results indicate that the community structures faithfully represent the structural features of oil-water flow patterns. Furthermore, we investigate the network statistic at different frequencies for each derived network and find that the frequency clustering coefficient enables to uncover the evolution of flow patterns and yield deep insights into the formation of flow structures. Current results present a first step towards a network visualization of complex flow patterns from a community structure perspective.

  10. A Compressive Multi-Frequency Linear Sampling Method for Underwater Acoustic Imaging.

    PubMed

    Alqadah, Hatim F

    2016-06-01

    This paper investigates the use of a qualitative inverse scattering method known as the linear sampling method (LSM) for imaging underwater scenes using limited aperture receiver configurations. The LSM is based on solving a set of unstable integral equations known as the far-field equations and whose stability breaks down even further for under-sampled observation aperture data. Based on the results of a recent study concerning multi-frequency LSM imaging, we propose an iterative inversion method that is founded upon a compressive sensing framework. In particular, we leverage multi-frequency diversity in the data by imposing a partial frequency variation prior on the solution which we show is justified when the frequency bandwidth is sampled finely enough. We formulate an alternating direction method of multiplier approach to minimize the proposed cost function. Proof of concept is established through numerically generated data as well as experimental acoustic measurements taken in a shallow pool facility at the U.S Naval Research Laboratory. PMID:27093719

  11. Advanced multi-frequency radar: Design, preliminary measurements and particle size distribution retrieval

    NASA Astrophysics Data System (ADS)

    Majurec, Ninoslav

    In the spring of 2001 the Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts began the development of an advanced Multi-Frequency Radar (AMFR) system for studying clouds and precipitation. This mobile radar was designed to consist of three polarimetric Doppler subsystems operating at Ku-band (13.4 GHz), Ka-band (35.6 GHz) and W-band (94.92 GHz). This combination of frequency bands allows a measurement of a wide range of atmospheric targets ranging from weakly reflecting clouds to strong precipitation. The antenna beamwidths at each frequency were intentionally matched, ensuring consistent sampling volume. Multi-frequency radar remote sensing techniques are not widely used because few multi-frequency radars are available to the science community. One exception is the 33 GHz/95 GHz UMass Cloud Profiling Radar System (CPRS), which AMFR is intended to replace. AMFR's multi-parameter capabilities are designed for characterizing the complex microphysics of layer clouds and precipitation processes in winter storms. AMFR will also play an important role in developing algorithms and validating measurements for an upcoming generation of space-borne radars. The frequency bands selected for AMFR match those of several sensors that have been deployed or are under development. These include the Japanese Aerospace Exploration Agencies (JAXA's) Tropical Rainfall Measuring Mission (TRMM) satellite Ku-band (13 GHz) radar, the CloudSat W-band (95 GHz) radar, and the Global Precipitation Mission (GPM) satellite radars at Ku-band and Ka-band. This dissertation describes the AMFR hardware design and development. Compared to CPRS, the addition of one extra frequency band (Ku) will extend AMFR's measurement capabilities towards the larger particle sizes (precipitation). AMFR's design is based around high-power klystron amplifiers. This ensures complete coherency (CPRS uses magnetrons and coherent-on-receive technique). The partial loss in sensitivity due to

  12. Multi-frequency local wavenumber analysis and ply correlation of delamination damage.

    PubMed

    Juarez, Peter D; Leckey, Cara A C

    2015-09-01

    Wavenumber domain analysis through use of scanning laser Doppler vibrometry has been shown to be effective for non-contact inspection of damage in composites. Qualitative and semi-quantitative local wavenumber analysis of realistic delamination damage and quantitative analysis of idealized damage scenarios (Teflon inserts) have been performed previously in the literature. This paper presents a new methodology based on multi-frequency local wavenumber analysis for quantitative assessment of multi-ply delamination damage in carbon fiber reinforced polymer (CFRP) composite specimens. The methodology is presented and applied to a real world damage scenario (impact damage in an aerospace CFRP composite). The methodology yields delamination size and also correlates local wavenumber results from multiple excitation frequencies to theoretical dispersion curves in order to robustly determine the delamination ply depth. Results from the wavenumber based technique are validated against a traditional nondestructive evaluation method. PMID:25980617

  13. Multi-frequency observation of Galactic micro-quasar Cygnus X-3 during flare

    NASA Astrophysics Data System (ADS)

    Patra, D.; Pal, S.; Ishwara-Chandra, C. H.; Rao, A. P.

    We studied the multi-frequency radio observations of the Galactic micro-quasar Cygnus X-3 using the Giant Metrewave Radio Telescope at 244, 325, 614 and 1280 MHz and Very Large Array at 8.43, 22.5 and 43.3 GHz during various flaring activities between 2006 to 2009. We have calculated the two point spectral index from the simultaneous observations at 244 and 614 MHz. These spectral index varies from positive (optically thick) and negative (optically thin) values which is consistent with the synchrotron self absorption model. We calculated some physical parameters such as the size of emitting region, turn over frequency and corresponding peak flux using the synchrotron self absorption model. The size of the emitting region are different at different time of the flare.

  14. Multi-frequency activation of neuronal networks by coordinated reset stimulation

    PubMed Central

    Lysyansky, Borys; Popovych, Oleksandr V.; Tass, Peter A.

    2011-01-01

    We computationally study whether it is possible to stimulate a neuronal population in such a way that its mean firing rate increases without an increase of the population's net synchronization. For this, we use coordinated reset (CR) stimulation, which has previously been developed to desynchronize populations of oscillatory neurons. Intriguingly, delivered to a population of predominantly silent FitzHugh–Nagumo or Hindmarsh–Rose neurons at sufficient stimulation amplitudes, CR robustly causes a multi-frequency activation: different Arnold tongues such as 1 : 1 or n : m entrained neuronal clusters emerge, which consist of phase-shifted sub clusters. Owing to the clustering pattern the neurons' timing is well balanced, so that in total there is no synchronization. Our findings may contribute to the development of novel and safe stimulation treatments that specifically counteract cerebral hypo-activity without promoting pathological synchronization or inducing epileptic seizures. PMID:22419975

  15. Three-dimensional ground penetrating radar imaging using multi-frequency diffraction tomography

    SciTech Connect

    Mast, J.E.; Johansson, E.M.

    1994-11-15

    In this talk we present results from a three-dimensional image reconstruction algorithm for impulse radar operating in monostatic pule-echo mode. The application of interest to us is the nondestructive evaluation of civil structures such as bridge decks. We use a multi-frequency diffraction tomography imaging technique in which coherent backward propagations of the received reflected wavefield form a spatial image of the scattering interfaces within the region of interest. This imaging technique provides high-resolution range and azimuthal visualization of the subsurface region. We incorporate the ability to image in planarly layered conductive media and apply the algorithm to experimental data from an offset radar system in which the radar antenna is not directly coupled to the surface of the region. We present a rendering in three-dimensions of the resulting image data which provides high-detail visualization.

  16. ARECIBO MULTI-FREQUENCY TIME-ALIGNED PULSAR AVERAGE-PROFILE AND POLARIZATION DATABASE

    SciTech Connect

    Hankins, Timothy H.; Rankin, Joanna M. E-mail: Joanna.Rankin@uvm.edu

    2010-01-15

    We present Arecibo time-aligned, total intensity profiles for 46 pulsars over an unusually wide range of radio frequencies and multi-frequency, polarization-angle density diagrams, and/or polarization profiles for 57 pulsars at some or all of the frequencies 50, 111/130, 430, and 1400 MHz. The frequency-dependent dispersion delay has been removed in order to align the profiles for study of their spectral evolution, and wherever possible the profiles of each pulsar are displayed on the same longitude scale. Most of the pulsars within Arecibo's declination range that are sufficiently bright for such spectral or single pulse analysis are included in this survey. The calibrated single pulse sequences and average profiles are available by web download for further study.

  17. Optimizing an Actuator Array for the Control of Multi-Frequency Noise in Aircraft Interiors

    NASA Technical Reports Server (NTRS)

    Palumbo, D. L.; Padula, S. L.

    1997-01-01

    Techniques developed for selecting an optimized actuator array for interior noise reduction at a single frequency are extended to the multi-frequency case. Transfer functions for 64 actuators were obtained at 5 frequencies from ground testing the rear section of a fully trimmed DC-9 fuselage. A single loudspeaker facing the left side of the aircraft was the primary source. A combinatorial search procedure (tabu search) was employed to find optimum actuator subsets of from 2 to 16 actuators. Noise reduction predictions derived from the transfer functions were used as a basis for evaluating actuator subsets during optimization. Results indicate that it is necessary to constrain actuator forces during optimization. Unconstrained optimizations selected actuators which require unrealistically large forces. Two methods of constraint are evaluated. It is shown that a fast, but approximate, method yields results equivalent to an accurate, but computationally expensive, method.

  18. A Multi-Frequency VLBA Survey of Interstellar Scattering in the Cygnus X Region

    NASA Astrophysics Data System (ADS)

    Mutel, R. L.; Molnar, L. A.; Spangler, S. R.

    1998-05-01

    We describe the results of a multi-frequency VLBA study of the scatter-broadened images of fifteen compact extragalactic sources. The sources are located along lines of sight which intercept the Cygnus X superbubble. We have used the phase structure function to determine the spatial spectrum of turbulence with high SNR on scales from 100 to 6,000 km. We will discuss evidence for detection of an inner scale length along some lines of sight as well as excess visibility amplitude for projected baseline lengths much greater than the diffractive scale. We also find that most scattered-broadened images are significantly elliptical with orientations which may be related to the large-scale magnetic field orientation in the Cygnus superbubble.

  19. The application of multi-frequency fringe projection profilometry on the measurement of biological tissues.

    PubMed

    Jiang, Chao; Jia, Shuhai; Xu, Yong; Bao, Qingchen; Dong, Jun; Lian, Qin

    2015-01-01

    A volume of research has been performed on the optical surface profilometry in the field of biomedicine and the optical system with the phase-measuring method becomes the main emphasis of the research. In this research, a brand new fringe projection profilometry with multiple frequencies is described for measuring the biological tissue. A pork liver, as an object, is regarded as a human organ and a DMD projector is used to generate the multi-frequency fringe patterns. The wrapped phase maps are obtained by means of the five-step phase shifting method and calculated via a peak searching algorithm in which the process of measuring the point on the surface of the object is independent so that the step of unwrapping the phase can be avoided. The final results given are acceptable which confirm this method and suggest its enormous potential for the biomedical measurements. PMID:26406029

  20. Quantifying the Effect of Component Covariances in CMB Extraction from Multi-frequency Data

    NASA Technical Reports Server (NTRS)

    Phillips, Nicholas G.

    2008-01-01

    Linear combination methods provide a global method for component separation of multi-frequency data. We present such a method that allows for consideration of possible covariances between the desired cosmic microwave background signal and various foreground signals that are also present. We also recover information on the foregrounds including the number of foregrounds, their spectra and templates. In all this, the covariances, which we would only expect to vanish 'in the mean' are included as parameters expressing the fundamental uncertainty due to this type of cosmic variance. When we make the reasonable assumption that the CMB is Gaussian, we can compute both a mean recovered CMB map and also an RMS error map, The mean map coincides with WMAP's Internal Linear Combination map.

  1. Composite Characterization Using Laser Doppler Vibrometry and Multi-Frequency Wavenumber Analysis

    NASA Technical Reports Server (NTRS)

    Juarez, Peter; Leckey, Cara

    2015-01-01

    NASA has recognized the need for better characterization of composite materials to support advances in aeronautics and the next generation of space exploration vehicles. An area of related research is the evaluation of impact induced delaminations. Presented is a non-contact method of measuring the ply depth of impact delamination damage in a composite through use of a Scanning Laser Doppler Vibrometer (SLDV), multi-frequency wavenumber analysis, and a wavenumber-ply correlation algorithm. A single acquisition of a chirp excited lamb wavefield in an impacted composite is post-processed into a numerous single frequency excitation wavefields through a deconvolution process. A spatially windowed wavenumber analysis then extracts local wavenumbers from the wavefield, which are then correlated to theoretical dispersion curves for ply depth determination. SLDV based methods to characterize as-manufactured composite variation using wavefield analysis will also be discussed.

  2. Multi-frequency, multi-messenger astrophysics with Swift. The case of blazars

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2015-09-01

    During its first 10 years of orbital operations Swift dedicated approximately 11% of its observing time to blazars, carrying out more than 12,000 observations of ∼1600 different objects, for a total exposure time of over 25 million seconds. In this paper I briefly discuss the impact that Swift is having on blazar multi-frequency and time-domain astrophysics, as well as how it is contributing to the opening of the era of multi-messenger astronomy. Finally, I present some preliminary results from a systematic analysis of a very large number of Swift XRT observations of blazars. All the "science ready" data products that are being generated by this project will be publicly released. Specifically, deconvolved X-ray spectra and best fit spectral parameters will be available through the ASDC "SED builder" tool ("https://tools.asdc.asi.it/SED")

  3. Shape reconstruction of the multi-scale rough surface from multi-frequency phaseless data

    NASA Astrophysics Data System (ADS)

    Bao, Gang; Zhang, Lei

    2016-08-01

    We consider the problem of reconstructing the shape of multi-scale sound-soft large rough surfaces from phases measurements of the scattered field generated by tapered waves with multiple frequencies impinging on a rough surface. To overcome both the ill-posedness and nonlinearity of this problem for a single frequency, the Landweber regularization method based on the adjoint of the nonlinear objective functional is used. When the multi-frequency data is available, an approximation method is introduced to estimate the large-scale structure of the rough surface using the data measurements at the lowest frequency. The obtained estimate serves as an initial guess for a recursive linearization algorithm in frequency, which is used to capture the small scale structure of the rough surface. Numerical experiments are presented to illustrate the effectiveness of the method.

  4. Design and characterization of a multi-frequency bioimpedance measurement prototype

    NASA Astrophysics Data System (ADS)

    Mattia Neto, O. E.; Porto, R. W.; Aya, J. C. C.

    2012-12-01

    A multi-frequency bioimpedance measurement prototype is proposed, validated and characterized. It consists of an Improved Howland Current Source controlled by voltage, a load voltage sensing scheme through a discrete 3-opamp instrumentation amplifier, a phase and quadrature demodulation setup through analog multipliers, and digitization and processing of the signals using a digital benchtop multimeter. The electrical characterization of the measurement channel was done for resistive loads only, on four different circuits. Measurements were made on 10 frequencies, from 100 kHz to 1 MHz, with 10 load resistances, from 100 Ω to 1 kΩ, to obtain linearity, absolute error and frequency response. The best performance among the four circuits was a maximum absolute error of 5.55 %, and -1.93 % of load current variation at the worst case scenario.

  5. Soil Moisture derivation from the multi-frequency sensor AMSR-2

    NASA Astrophysics Data System (ADS)

    Parinussa, Robert; de Nijs, Anne; de Jeu, Richard; Holmes, Thomas; Dorigo, Wouter; Wanders, Niko; Schellekens, Jaap

    2015-04-01

    We present a method to derive soil moisture from the multi-frequency sensor Advanced Microwave Scanning Radiometer 2 (AMSR-2). Its predecessor, the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), has already provided Earth scientists with a consistent and continuous global soil moisture dataset. However, the AMSR-2 sensor has one big advantage in relation to the AMSR-E sensor; is has an additional channel in the C-band frequency (7.3 GHz). This channel creates the opportunity to have a better screening for Radio Frequency Interference (RFI) and could eventually lead to improved soil moisture retrievals. The soil moisture retrievals from AMSR-2 we present here use the Land Parameter Retrieval Model (LPRM) in combination with a new radio frequency interference masking method. We used observations of the multi-frequency microwave radiometer onboard the Tropical Rainfall Measuring Mission (TRMM) satellite to intercalibrate the brightness temperatures in order to improve consistency between AMSR-E and AMSR-2. Several scenarios to accomplish synergy between the AMSR-E and AMSR-2 soil moisture products were evaluated. A global comparison of soil moisture retrievals against ERA Interim re-analysis soil moisture demonstrates the need for an intercalibration procedure. Several different scenarios based on filtering were tested and the impact on the soil moisture retrievals was evaluated against two independent reference soil moisture datasets (reanalysis and in situ soil moisture) that cover the observation periods of the AMSR-E and AMSR-2 sensors. Results show a high degree of consistency between both satellite products and two independent reference products for the soil moisture products. In addition, the added value of an additional frequency for RFI detection is demonstrated within this study with a reduction of the total contaminated pixels in the 6.9 GHz of 66% for horizontal observations and even 85% for vertical observations when 7.3 and 10

  6. SU-E-I-52: Validation of Multi-Frequency Electrical Impedance Tomography Using Computed Tomography

    SciTech Connect

    Kohli, K; Liu, F; Krishnan, K

    2014-06-01

    Purpose: Multi-frequency EIT has been reported to be a potential tool in distinguishing a tissue anomaly from background. In this study, we investigate the feasibility of acquiring functional information by comparing multi-frequency EIT images in reference to the structural information from the CT image through fusion. Methods: EIT data was acquired from a slice of winter melon using sixteen electrodes around the phantom, injecting a current of 0.4mA at 100, 66, 24.8 and 9.9 kHz. Differential EIT images were generated by considering different combinations of pair frequencies, one serving as reference data and the other as test data. The experiment was repeated after creating an anomaly in the form of an off-centered cavity of diameter 4.5 cm inside the melon. All EIT images were reconstructed using Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS) package in 2-D differential imaging mode using one-step Gaussian Newton minimization solver. CT image of the melon was obtained using a Phillips CT Scanner. A segmented binary mask image was generated based on the reference electrode position and the CT image to define the regions of interest. The region selected by the user was fused with the CT image through logical indexing. Results: Differential images based on the reference and test signal frequencies were reconstructed from EIT data. Result illustrated distinct structural inhomogeneity in seeded region compared to fruit flesh. The seeded region was seen as a higherimpedance region if the test frequency was lower than the base frequency in the differential EIT reconstruction. When the test frequency was higher than the base frequency, the signal experienced less electrical impedance in the seeded region during the EIT data acquisition. Conclusion: Frequency-based differential EIT imaging can be explored to provide additional functional information along with structural information from CT for identifying different tissues.

  7. Multi-frequency THz Heterodyne Spectroscopy using Electro-Optic Sampling

    NASA Astrophysics Data System (ADS)

    Jones, David

    2010-03-01

    Multi-frequency heterodyne spectroscopy, developed by two groups (Schiller as well as van der Weide, Keilmann and co-workers) uses one optical femtosecond frequency comb (FFC) to probe a sample. A second FFC with a slightly detuned spacing is used as a multi frequency local oscillator to uniquely map the broadband optical spectroscopic information to the RF domain where it can be easily analyzed. Researchers at NIST (Coddington et al) have realized the full potential of this technique by tightly locking the detuned combs together using optical locking techniques. It is of considerable interest to extend such capabilities to access the so-called molecular vibrational ``fingerprint'' range of approximately 10 to 100 THz (300 to 3000 cm-1). A transfer of the direct heterodyne detection approach used in the optical regime down to this frequency range is fraught with difficulties including significantly lower power of the probe THz frequency comb. In addition, a low noise detector with a relatively fast RF response (>100 MHz at a minimum) is required. An alternative, indirect detection technique for detecting THz signals is electro-optic sampling (EOS). It has employed for time domain THz spectroscopic applications for a number of years with a demonstrated spectral detection ranging from 0.5 THz range to over 100 THz. Through careful analysis of the EOS we show how electro-optic sampling of THz frequency comb by a detuned optical FFC followed by direct optical detection of the optical sampling beam enables conversion of the THz spectroscopic data directly to the RF domain. In particular, we show there is a one-to-one correspondence between a detected RF heterodyne beat and THz comb element. Numerical simulations predict excellent signal to noise ratio of the RF beats (20 dB) with modest acquisition times (10 μs). We will also summarize our progress toward experimental realization of such a system.

  8. Multi-frequency, finite-wavelength and dc-augmentation effects in large area capacitive sources

    NASA Astrophysics Data System (ADS)

    Kushner, Mark

    2009-10-01

    The scaling of high frequency, multi-frequency capacitively coupled plasmas (CCPs) to large areas has many challenges. It has been well established that electromagnetic (EM) effects become increasingly more important as the frequency of excitation increases while the diameter of the substrate also increases. The complexity of the system increases with the addition of dc-augmentation. Although much as been learned about EM effects, scaling laws are difficult to develop because the discharge characteristics are functions of the frequency dependence of the conductivity, the response of the electron energy distribution (EED) to the electric fields that penetrate into the plasma, the geometry of the reactor, gas mixture, pressure and dc augmentation power. In the case of multi-frequency excitation, the coupling of low and high frequencies through surface waves and through the bulk plasma is also an issue. In this talk we will discuss results from a computational investigation of multi- and high- frequency (up to 200 MHz) excitation of CCPs having diameters up to 450 mm, with and without dc augmentation. The model used in this study includes a full time-domain solution of Maxwell's equations that enables investigation of coupling between frequencies. A Monte Carlo simulation is used to predict EEDs as a function of position and ion energy distributions to the substrate. Gas mixtures (e.g., Ar and Ar/CF4), pressures (10 mTorr to 100 mTorr) and geometry (gap size) are investigated. Methods to minimize EM effects will be discussed by using variable conductivity and shaped electrodes; and segmented electrodes in which the electrical path from the generator to any point in the plasma is made as consistent as possible.

  9. Thrombolysis using multi-frequency high intensity focused ultrasound at MHz range: an in vitro study

    NASA Astrophysics Data System (ADS)

    Suo, Dingjie; Guo, Sijia; Lin, Weili; Jiang, Xiaoning; Jing, Yun

    2015-09-01

    High intensity focused ultrasound (HIFU) based thrombolysis has emerged as a promising drug-free treatment approach for ischemic stroke. The large amount of acoustic power required by this approach, however, poses a critical challenge to the future clinical translation. In this study, multi-frequency acoustic waves at MHz range (near 1.5 MHz) were introduced as HIFU excitations to reduce the required power for treatment as well as the treatment time. In vitro bovine blood clots weighing around 150 mg were treated by single-frequency and multi-frequency HIFU. The pulse length was 2 ms for all experiments except the ones where the duty cycle was changed. It was found that dual-frequency thrombolysis efficiency was statistically better than single-frequency under the same acoustic power and excitation condition. When varying the acoustic power but fixing the duty cycle at 5%, it was found that dual-frequency ultrasound can save almost 30% power in order to achieve the same thrombolysis efficiency. In the experiment where the duty cycle was increased from 0.5% to 10%, it was shown that dual-frequency ultrasound can achieve the same thrombolysis efficiency with only half of the duty cycle of single-frequency. Dual-frequency ultrasound could also accelerate the thrombolysis by a factor of 2-4 as demonstrated in this study. No significant differences were found between dual-frequencies with different frequency differences (0.025, 0.05, and 0.1 MHz) and between dual-frequency and triple-frequency. The measured cavitation doses of dual-frequency and triple-frequency excitations were at about the same level but both were significantly higher than that of single-frequency.

  10. Eliminating diffraction effects during multi-frequency correction in global navigation satellite systems

    NASA Astrophysics Data System (ADS)

    Tinin, M. V.

    2015-05-01

    In the geometrical optics approximation, the ionospheric part of error in measuring phase and code delays of the satellite signal may be represented as a rapidly decreasing series in inverse power of frequency. Such a simple frequency dependence allows us to use multi-frequency measurements for eliminating the error in such multi-frequency Global Navigation Satellite Systems as GPS, GLONASS, BeiDou, and Galileo. However, the elimination of errors is handicapped by diffraction effects during signal propagation through turbulent ionospheric plasma. The numerical simulation has shown that when using the spatial processing in the form of Fresnel inversion the transition from dual-frequency to triple-frequency measurements reduces the average error of measurement. Yet fluctuations of the error diminish only if the inner scale exceeds the Fresnel radius. In the opposite case of excess of the Fresnel radius over the inner scale, the random component of the residual error is growing during the transition to triple-frequency measurements. The numerical simulation results also suggest that the Fresnel spatial processing in dual-frequency measurements at the optimal distance to the virtual screen can reduce the average error from centimeter to submillimeter level, which renders the transition to triple-frequency measurements unnecessary. The study of the residual error dependence on the distance from the virtual screen to the observer has revealed that the optimum value of this distance may be found from the minimum condition of amplitude scintillation index of the processed signal. The signal thus processed may be utilized both in geodetic precise measurements and in diagnostics of the lower atmosphere.

  11. Multi-frequency Radio Profiles of PSR B1133+16: Radiation Location and Particle Energy

    NASA Astrophysics Data System (ADS)

    Lu, J. G.; Du, Y. J.; Hao, L. F.; Yan, Z.; Liu, Z. Y.; Lee, K. J.; Qiao, G. J.; Shang, L. H.; Wang, M.; Xu, R. X.; Yue, Y. L.; Zhi, Q. J.

    2016-01-01

    The pulse profile of PSR B1133+16 is usually regarded as a conal double structure. However, its multi-frequency profiles cannot simply be fitted with two Gaussian functions, and a third component is always needed to fit the bridge region (between two peaks). This would introduce additional, redundant parameters. In this paper, through a comparison of five fitting functions (Gaussian, von Mises, hyperbolic secant, square hyperbolic secant, and Lorentz), it is found that the square hyperbolic secant function can best reproduce the profile, yielding an improved fit. Moreover, a symmetric 2D radiation beam function, instead of a simple 1D Gaussian function, is used to fit the profile. Each profile with either well-resolved or not-so-well-resolved peaks could be fitted adequately using this beam function, and the bridge emission between the two peaks does not need to be a new component. Adopting inclination and impact angles based on polarization measurements, the opening angle ({θ }μ 0) of the radiation beam in a certain frequency band is derived from beam-function fitting. The corresponding radiation altitudes are then calculated. Based on multi-frequency profiles, we also computed the Lorentz factors of the particles and their dispersion at those locations in both the curvature-radiation and inverse-Compton-scattering models. We found that the Lorentz factors of the particles decrease rapidly as the radiation altitude increases. Besides, the radiation prefers to be generated in an annular region rather than the core region, and this needs further validation.

  12. Perceptual and Attentional Influences on Continuous 2:1 and 3:2 Multi-Frequency Bimanual Coordination

    ERIC Educational Resources Information Center

    Kovacs, Attila J.; Buchanan, John J.; Shea, Charles H.

    2010-01-01

    Two experiments were conducted to determine if multi-frequency (2:1 and 3:2) coordination between the limbs is enhanced when integrated feedback is provided in the form of Lissajous plots, attention demands are reduced, and attempts to consciously coordinate the limbs are not encouraged. To determine the influence of vision of the limbs, covered…

  13. Multi-frequency simultaneous measurement of bioimpedance spectroscopy based on a low crest factor multisine excitation.

    PubMed

    Yang, Yuxiang; Zhang, Fu; Tao, Kun; Wang, Lianhuan; Wen, He; Teng, Zhaosheng

    2015-03-01

    Bioimpedance spectroscopy (BIS) is becoming a powerful diagnostic tool for a wide variety of medical applications, and the multi-frequency simultaneous (MFS) measurement of BIS can greatly reduce measurement time and record the transient physiological status of a living body compared with traditional frequency-sweep measurement technology. This paper adopts the Van der Ouderaa's multisine, which has 31 equidistant and flat amplitude spectra and a low crest factor of 1.405 as the broadband excitation, and realizes the MFS measurement of BIS by means of spectral analysis using the fast Fourier transform algorithm. The approach to implement the multisine based on a field-programmable gate array and a digital to analog converter is described in detail, and impedance measurement experiments are performed on three resistance-capitance three-element phantoms. Experimental results show a commendable accuracy with a mean relative error of 0.55% for the impedance amplitudes, and a mean absolute error of 0.20° for the impedance phases on the 31 frequencies ranging linearly from 32 to 992 kHz. This paper validates the feasibility of the MFS technology for BIS measurement based on the multisine excitation. PMID:25679488

  14. Array processing for RFID tag localization exploiting multi-frequency signals

    NASA Astrophysics Data System (ADS)

    Zhang, Yimin; Li, Xin; Amin, Moeness G.

    2009-05-01

    RFID is an increasingly valuable business and technology tool for electronically identifying, locating, and tracking products, assets, and personnel. As a result, precise positioning and tracking of RFID tags and readers have received considerable attention from both academic and industrial communities. Finding the position of RFID tags is considered an important task in various real-time locating systems (RTLS). As such, numerous RFID localization products have been developed for various applications. The majority of RFID positioning systems is based on the fusion of pieces of relevant information, such as the range and the direction-of-arrival (DOA). For example, trilateration can determine the tag position by using the range information of the tag estimated from three or more spatially separated reader antennas. Triangulation is another method to locate RFID tags that use the direction-of-arrival (DOA) information estimated at multiple spatially separated locations. The RFID tag positions can also be determined through hybrid techniques that combine the range and DOA information. The focus of this paper to study the design and performance of the localization of passive RFID tags using array processing techniques in a multipath environment, and exploiting multi-frequency CW signals. The latter are used to decorrelate the coherent multipath signals for effective DOA estimation and for the purpose of accurate range estimation. Accordingly, the spatial and frequency dimensionalities are fully utilized for robust and accurate positioning of RFID tags.

  15. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    PubMed

    Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J

    2016-08-01

    Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment. PMID:26863670

  16. Sonic IR crack detection of aircraft turbine engine blades with multi-frequency ultrasound excitations

    NASA Astrophysics Data System (ADS)

    Zhang, Ding; Han, Xiaoyan; Newaz, Golam

    2014-02-01

    Effectively and accurately detecting cracks or defects in critical engine components, such as turbine engine blades, is very important for aircraft safety. Sonic Infrared (IR) Imaging is such a technology with great potential for these applications. This technology combines ultrasound excitation and IR imaging to identify cracks and flaws in targets. In general, failure of engine components, such as blades, begins with tiny cracks. Since the attenuation of the ultrasound wave propagation in turbine engine blades is small, the efficiency of crack detection in turbine engine blades can be quite high. The authors at Wayne State University have been developing the technology as a reliable tool for the future field use in aircraft engines and engine parts. One part of the development is to use finite element modeling to assist our understanding of effects of different parameters on crack heating while experimentally hard to achieve. The development has been focused with single frequency ultrasound excitation and some results have been presented in a previous conference. We are currently working on multi-frequency excitation models. The study will provide results and insights of the efficiency of different frequency excitation sources to foster the development of the technology for crack detection in aircraft engine components.

  17. A Multi-Frequency Wide-Swath Spaceborne Cloud and Precipitation Imaging Radar

    NASA Technical Reports Server (NTRS)

    Li, Lihua; Racette, Paul; Heymsfield, Gary; McLinden, Matthew; Venkatesh, Vijay; Coon, Michael; Perrine, Martin; Park, Richard; Cooley, Michael; Stenger, Pete; Spence, Thomas; Retelny, Tom

    2016-01-01

    Microwave and millimeter-wave radars have proven their effectiveness in cloud and precipitation observations. The NASA Earth Science Decadal Survey (DS) Aerosol, Cloud and Ecosystems (ACE) mission calls for a dual-frequency cloud radar (W band 94 GHz and Ka-band 35 GHz) for global measurements of cloud microphysical properties. Recently, there have been discussions of utilizing a tri-frequency (KuKaW-band) radar for a combined ACE and Global Precipitation Measurement (GPM) follow-on mission that has evolved into the Cloud and Precipitation Process Mission (CaPPM) concept. In this presentation we will give an overview of the technology development efforts at the NASA Goddard Space Flight Center (GSFC) and at Northrop Grumman Electronic Systems (NGES) through projects funded by the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). Our primary objective of this research is to advance the key enabling technologies for a tri-frequency (KuKaW-band) shared-aperture spaceborne imaging radar to provide unprecedented, simultaneous multi-frequency measurements that will enhance understanding of the effects of clouds and precipitation and their interaction on Earth climate change. Research effort has been focused on concept design and trade studies of the tri-frequency radar; investigating architectures that provide tri-band shared-aperture capability; advancing the development of the Ka band active electronically scanned array (AESA) transmitreceive (TR) module, and development of the advanced radar backend electronics.

  18. Data Acquisition System for Multi-Frequency Radar Flight Operations Preparation

    NASA Technical Reports Server (NTRS)

    Leachman, Jonathan

    2010-01-01

    A three-channel data acquisition system was developed for the NASA Multi-Frequency Radar (MFR) system. The system is based on a commercial-off-the-shelf (COTS) industrial PC (personal computer) and two dual-channel 14-bit digital receiver cards. The decimated complex envelope representations of the three radar signals are passed to the host PC via the PCI bus, and then processed in parallel by multiple cores of the PC CPU (central processing unit). The innovation is this parallelization of the radar data processing using multiple cores of a standard COTS multi-core CPU. The data processing portion of the data acquisition software was built using autonomous program modules or threads, which can run simultaneously on different cores. A master program module calculates the optimal number of processing threads, launches them, and continually supplies each with data. The benefit of this new parallel software architecture is that COTS PCs can be used to implement increasingly complex processing algorithms on an increasing number of radar range gates and data rates. As new PCs become available with higher numbers of CPU cores, the software will automatically utilize the additional computational capacity.

  19. Multi-frequency study of a double-double radio galaxy J1706+4340

    NASA Astrophysics Data System (ADS)

    Marecki, A.; Jamrozy, M.; Machalski, J.

    2016-08-01

    We report the outcome of multi-frequency radio observations of a double-double radio source (DDRS) J1706+4340 carried out with the VLA and GMRT. After supplementing our own data with those available in the literature, we collected a considerable set of radio measurements covering the range from 74 MHz to 8460 MHz. This has enabled us to perform a comprehensive review of physical properties of the source and its dynamical evolution analysis. In particular, we found that, while the age of the large-scale outer lobes is in the range 260 - 300 Myr, the renewal of the jet activity, which is directly responsible for the double-double structure, took place only about 12 Myr ago after about 27-Myr-long period of quiescence. Another important property of J1706+4340 we found is that the injection spectral indices and the jet powers for the inner and the outer doubles are very similar. This implies that it is the spin of the supermassive black hole (SMBH) rather than e.g. an instability of the accretion disk that is likely responsible for the jet production and its properties.

  20. Development of a Multi-frequency Interferometer Telescope for Radio Astronomy (MITRA)

    NASA Astrophysics Data System (ADS)

    Ingala, Dominique Guelord Kumamputu

    2015-03-01

    This dissertation describes the development and construction of the Multi-frequency Interferometer Telescope for Radio Astronomy (MITRA) at the Durban University of Technology. The MITRA station consists of 2 antenna arrays separated by a baseline distance of 8 m. Each array consists of 8 Log-Periodic Dipole Antennas (LPDAs) operating from 200 MHz to 800 MHz. The design and construction of the LPDA antenna and receiver system is described. The receiver topology provides an equivalent noise temperature of 113.1 K and 55.1 dB of gain. The Intermediate Frequency (IF) stage was designed to produce a fixed IF frequency of 800 MHz. The digital Back-End and correlator were implemented using a low cost Software Defined Radio (SDR) platform and Gnu-Radio software. Gnu-Octave was used for data analysis to generate the relevant received signal parameters including total power, real, and imaginary, magnitude and phase components. Measured results show that interference fringes were successfully detected within the bandwidth of the receiver using a Radio Frequency (RF) generator as a simulated source. This research was presented at the IEEE Africon 2013 / URSI Session Mauritius, and published in the proceedings.

  1. Multi-frequency modes in superconducting resonators: Bridging frequency gaps in off-resonant couplings

    NASA Astrophysics Data System (ADS)

    Andersen, Christian Kraglund; Mølmer, Klaus

    2015-03-01

    A SQUID inserted in a superconducting waveguide resonator imposes current and voltage boundary conditions that makes it suitable as a tuning element for the resonator modes. If such a SQUID element is subject to a periodically varying magnetic flux, the resonator modes acquire frequency side bands. We calculate the multi-frequency eigenmodes and these can couple resonantly to physical systems with different transition frequencies and this makes the resonator an efficient quantum bus for state transfer and coherent quantum operations in hybrid quantum systems. As an example of the application, we determine their coupling to transmon qubits with different frequencies and we present a bi-chromatic scheme for entanglement and gate operations. In this calculation, we obtain a maximally entangled state with a fidelity F = 95 % . Our proposal is competitive with the achievements of other entanglement-gates with superconducting devices and it may offer some advantages: (i) There is no need for additional control lines and dephasing associated with the conventional frequency tuning of qubits. (ii) When our qubits are idle, they are far detuned with respect to each other and to the resonator, and hence they are immune to cross talk and Purcell-enhanced decay.

  2. The study of multi-frequency scattering of 10 radio pulsars

    NASA Astrophysics Data System (ADS)

    Lewandowski, Wojciech; Rożko, Karolina; Kijak, Jarosław; Bhattacharyya, Bhaswati; Roy, Jayanta

    2015-12-01

    We present the results of the multi-frequency scatter time measurements for 10 radio pulsars that were relatively less studied in this regard. The observations were performed using the Giant Metrewave Radio Telescope at the observing frequencies of 150, 235, 325, 610 and 1060 MHz. The data we collected, in conjunction with the results from other frequencies published earlier, allowed us to estimate the scatter time frequency scaling indices for eight of these sources. For PSR J1852-0635, it became evident that its profile undergoes a strong evolution with frequency, which makes the scatter time measurements difficult to perform, and for PSR J1835-1020 we were able to obtain reliable pulse broadening estimates at only two frequencies. We used the eight frequency scaling indices to estimate both: the electron density fluctuation strengths along the respective lines of sight and the standardized amount of scattering at the frequency of 1 GHz. Combining the new data with the results published earlier by Lewandowski et al., we revisited the scaling index versus the dispersion measure (DM) relation, and similarly to some of the earlier studies, we show that the average value of the scaling index deviates from the theoretical predictions for large-DM pulsars; however, it reaches the magnitude claimed by Löhmer et al. only for pulsars with very large DMs (>650 pc cm-3). We also investigated the dependence of the scattering strength indicators on the pulsar distance, DM and the position of the source in the Milky Way Galaxy.

  3. Sonic IR crack detection of aircraft turbine engine blades with multi-frequency ultrasound excitations

    SciTech Connect

    Zhang, Ding; Han, Xiaoyan; Newaz, Golam

    2014-02-18

    Effectively and accurately detecting cracks or defects in critical engine components, such as turbine engine blades, is very important for aircraft safety. Sonic Infrared (IR) Imaging is such a technology with great potential for these applications. This technology combines ultrasound excitation and IR imaging to identify cracks and flaws in targets. In general, failure of engine components, such as blades, begins with tiny cracks. Since the attenuation of the ultrasound wave propagation in turbine engine blades is small, the efficiency of crack detection in turbine engine blades can be quite high. The authors at Wayne State University have been developing the technology as a reliable tool for the future field use in aircraft engines and engine parts. One part of the development is to use finite element modeling to assist our understanding of effects of different parameters on crack heating while experimentally hard to achieve. The development has been focused with single frequency ultrasound excitation and some results have been presented in a previous conference. We are currently working on multi-frequency excitation models. The study will provide results and insights of the efficiency of different frequency excitation sources to foster the development of the technology for crack detection in aircraft engine components.

  4. Developing a small multi frequency synthetic aperture radar for UAS operation: the SlimSAR

    NASA Astrophysics Data System (ADS)

    Zaugg, Evan; Edwards, Matthew; Margulis, Alex

    2010-04-01

    The SlimSAR is a small, low-cost, Synthetic Aperture Radar (SAR) and represents a new advancement in high-performance SAR. ARTEMIS employed a unique design methodology in designing the SlimSAR that exploits previous developments. The system is designed to be smaller, lighter, and more flexible while consuming less power than typical SAR systems. The system consists of an L-band core and frequency block converters and is very suitable for use on a number of small UAS's. Both linear-frequency-modulated continuous-wave (LFM-CW) and pulsed modes have been tested. The LFM-CW operation achieves high signal-to-noise ratio while transmitting with less peak power than a comparable pulsed system. The flexible control software allows us to change the radar parameters in flight. The system has a built-in high quality GPS/IMU motion measurement solution and can also be packaged with a small data link and a gimbal for high frequency antennas. Multi-frequency SAR provides day and night imaging through smoke, dust, rain, and clouds with the advantages of additional capabilities at different frequencies (i.e. dry ground and foliage penetration at low frequencies, and change detection at high frequencies.)

  5. Multi-frequency observation of high mass X-ray binary Cygnus X-3 during flares

    NASA Astrophysics Data System (ADS)

    Pal, Sabyasachi; Patra, Dusmanta; Ishwara-Chandra, C. H.; Rao, A. P.

    2016-07-01

    We studied the multi-frequency properties of the Galactic high mass X-ray binary Cygnus X-3 during various flaring activities using The Rossi X-ray Timing Explorer (RXTE), the Giant Metrewave Radio Telescope (GMRT), Jansky Very Large Array (JVLA) etc. The flare of 2006 May-June was one of the largest flare in the history of the source which is thoroughly discussed. We also observed few large flares of this source between 2007 and 2009. We commented on correlation and lag between X-ray and radio emissions during flares. We construct the radio spectrum of the source in the rising and fading phase of flares using GMRT, JVLA and published results using RATAN. We clearly see that the turn-over frequency is shifting towards lower frequencies as the flares evolve gradually. The two point spectral index between 614 MHz and 235 MHz varies from positive (optically thick) and negative (optically thin) values which is consistent with the synchrotron self absorption model. We calculated some physical parameters of the source such as the size of emitting region using the synchrotron self absorption model. The size of the emitting region expands with the flare. We estimate the velocity of the expansion of the blob in the non-relativistic range from the expansion of the size of emitting region.

  6. PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Young; Trippe, Sascha; Sohn, Bong Won; Oh, Junghwan; Park, Jong-Ho; Lee, Sang-Sung; Lee, Taeseok; Kim, Daewon

    2015-10-01

    Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to >10^{8.01} K and >10^{9.86} K, respectively. Degrees of linear polarization m_{L} are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with m_{L} ˜ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.

  7. Multi-frequency solar observations at Metsähovi Radio Observatory and KAIRA

    NASA Astrophysics Data System (ADS)

    Kallunki, J.; Uunila, M.; McKay-Bukowski, D.

    2015-08-01

    We describe solar observations carried out for the first time jointly with Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) and Aalto University Metsähovi Radio Observatory (MRO). KAIRA is new radio antenna array observing the decimeter and meter wavelength range. It is located near Kilpisjärvi, Finland, and operated by the Sodankylä Geophysical Observatory, University of Oulu. We investigate the feasibility of KAIRA for solar observations, and the additional benefits of carrying out multi-instrument solar observations with KAIRA and the MRO facilities, which are already used for regular solar observations. The data measured with three instruments at MRO, and with KAIRA during time period 2014 April-October were analyzed. One solar radio event, measured on 2014 April 18, was studied in detail. Seven solar flares were recorded with at least two of the three instruments at MRO, and with KAIRA during the chosen time period. KAIRA is a great versatile asset as a new Finnish instrument that can also be used for solar observations. Collaboration observations with MRO instruments and KAIRA enable detailed multi-frequency solar flare analysis. Flare pulsations, flare statistics and radio spectra of single flares can be investigated due to the broad frequency range observations. The Northern locations of both MRO and KAIRA make as long as 15-hour unique solar observations possible during summer time.

  8. Multi-frequency auditory stimulation disrupts spindling activity in anesthetized animals.

    PubMed

    Britvina, T; Eggermont, J J

    2008-02-01

    It is often implied that during the occurrence of spindle oscillations, thalamocortical neurons do not respond to signals from the outside world. Since recording of sound-evoked activity from cat auditory cortex is common during spindling this implies that sound stimulation changes the spindle-related brain state. Local field potentials and multi-unit activity recorded from cat primary auditory cortex under ketamine anesthesia during successive silence-stimulus-silence conditions were used to investigate the effect of sound on cortical spindle oscillations. Multi-frequency stimulation suppresses spindle waves, as shown by the decrease of spectral power within the spindle frequency range during stimulation as compared with the previous silent period. We show that the percentage suppression is independent of the power of the spindle waves during silence, and that the suppression of spindle power occurs very fast after stimulus onset. The global inter-spindle rhythm was not disturbed during stimulation. Spectrotemporal and correlation analysis revealed that beta waves (15-26 Hz), and to a lesser extent delta waves, were modulated by the same inter-spindle rhythm as spindle oscillations. The suppression of spindle power during stimulation had no effect on the spatial correlation of spindle waves. Firing rates increased under stimulation and spectro-temporal receptive fields could reliably be obtained. The possible mechanism of suppression of spindle waves is discussed and it is suggested that suppression likely occurs through activity of the specific auditory pathway. PMID:18164553

  9. Impurities and electron spin relaxations in nanodiamonds studied by multi-frequency electron spin resonance

    NASA Astrophysics Data System (ADS)

    Cho, Franklin; Takahashi, Susumu

    2014-03-01

    Nano-sized diamond or nanodiamond is a fascinating material for potential applications of fluorescence imaging and magnetic sensing of biological systems via nitrogen-vacancy defect centers in diamonds. Sensitivity of the magnetic sensing strongly depends on coupling to surrounding environmental noises, thus understanding of the environment is critical to realize the application. In the present study, we employ multi-frequency (X-band, 115 GHz and 230 GHz) continuous-wave (cw) and pulsed electron spin resonance (ESR) spectroscopy to investigate impurity contents and spin relaxation properties in various sizes of nanodiamonds. Spectra taken with our home-built 230/115 GHz cw/pulsed ESR spectrometer shows presence of two major impurity contents; single substitutional nitrogen impurities (P1) also common in bulk diamonds and paramagnetic impurities (denoted as X) unique to nanodiamonds. The ESR measurement also shows a strong dependence of the population ratio between P1 and X on particle size. Furthermore, we will discuss the nature of spin-lattice relaxation time T1 of nanodiamonds studied by pulsed ESR measurements at X-band, 115 GHz and 230 GHz.

  10. Multi-frequency, multi-messenger astrophysics with blazars at ASDC and BSDC

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2015-12-01

    In this contribution I discuss the impact that blazars are having on today's multi-frequency and time-domain astrophysics, as well as how they are contributing to the opening of the era of multi-messenger astronomy. In this context I report some preliminary results from a systematic spectral and timing analysis carried out at ASDC on a very large number of X-ray observations of blazars. I also describe some of the on-going activities dedicated to the set up a new research oriented data center within ICRANet, called the Brazilian Science Data Center or BSDC, capitalising on the extensive experience on scientific data management of the ASDC, on the theoretical astrophysics background of ICRANet, and on local specific expertise. Both the ASDC and BSDC are actively accumulating "science ready" data products on blazars, which will be made available through the ASDC "SED builder" tool (https://tools.asdc.asi.it/SED) and by means of interactive tables reachable at the web sites of both centers.

  11. Column Path Length Measurements Using a Multi-Frequency, Intensity-Modulated Continuous-Wave (IM-CW) Laser Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    Harrison, F. W.; Lin, B.; Browell, E. V.; Dobler, J.; McGregor, D.; Kooi, S. A.; Collins, J. E.

    2012-12-01

    Accurate understanding of carbon balance in the environment is critical to projections of the future evolution of the Earth's climate. As a result, the NRC Decadal Survey (DS) of Earth Science and Applications from Space identified Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) as a mid-term (Tier II) mission. The active space remote measurement of the column CO2 mixing ratio (XCO2) for the ASCENDS mission requires the simultaneous measurement of the CO2 and O2 number density and the column path length over which they are measured in order to derive the average XCO2 column. This paper presents methods for measuring the path lengths of the CO2 and O2 measurements that are inherent to the Multi-Functional Fiber Laser Lidar (MFLL), a laser absorption spectrometer (LAS) system under development for the ASCENDS mission. The MFLL is a multi-frequency intensity-modulated continuous-wave (IM-CW) LAS operating near 1.57 and 1.26 μm that uses a range-encoded modulation technique to minimize bias from thin clouds in the CO2 and O2 column measurements while simultaneously measuring the path length to the surface and to intervening cloud layers. This paper discusses the latest MFLL ground and flight test results. During these tests, range-encoded modulation techniques were demonstrated for path length measurements and the MFLL remote CO2 column measurements were evaluated against in situ CO2 measurements. This paper describes the encoding techniques employed, presents an approach for obtaining column path length measurements during CO2 retrievals, and presents the accuracy and precision of the technique. Measurement of path length meeting ASCENDS requirements of approximately 2-m precision were obtained in ground testing and demonstrated during flights over Railroad Valley, NV.

  12. Multi-frequency excitation of stiffened triangular plates for large amplitude oscillations

    NASA Astrophysics Data System (ADS)

    Askari, H.; Saadatnia, Z.; Esmailzadeh, E.; Younesian, D.

    2014-10-01

    Free and forced vibrations of triangular plate are investigated. Diverse types of stiffeners were attached onto the plate to suppress the undesirable large-amplitude oscillations. The governing equation of motion for a triangular plate, based on the von Kármán theory, is developed and the nonlinear ordinary differential equation of the system using Galerkin approach is obtained. Closed-form expressions for the free undamped and large-amplitude vibration of an orthotropic triangular elastic plate are presented using the two well-known analytical methods, namely, the energy balance method and the variational approach. The frequency responses in the closed-form are presented and their sensitivities with respect to the initial amplitudes are studied. An error analysis is performed and the vibration behavior, as well as the accuracy of the solution methods, is evaluated. Different types of the stiffened triangular plates are considered in order to cover a wide range of practical applications. Numerical simulations are carried out and the validity of the solution procedure is explored. It is demonstrated that the two methods of energy balance and variational approach have been quite straightforward and reliable techniques to solve those nonlinear differential equations. Subsequently, due to the importance of multiple resonant responses in engineering design, multi-frequency excitations are considered. It is assumed that three periodic forces are applied to the plate in three specific positions. The multiple time scaling method is utilized to obtain approximate solutions for the frequency resonance cases. Influences of different parameters, namely, the position of applied forces, geometry and the number of stiffeners on the frequency response of the triangular plates are examined.

  13. A fully parallel multi-frequency EIT system with flexible electrode configuration: KHU Mark2.

    PubMed

    Oh, Tong In; Wi, Hun; Kim, Do Yub; Yoo, Pil Joong; Woo, Eung Je

    2011-07-01

    We report the development of a new multi-frequency electrical impedance tomography (EIT) system called the KHU Mark2. It is descended from the KHU Mark1 in terms of technical details such as digital waveform generation, Howland current source with multiple generalized impedance converters and digital phase-sensitive demodulators. New features include flexible electrode configurations to accommodate application-specific requirements, multiple independent current sources and voltmeters for fully parallel operations, improved data acquisition speeds for faster frame rates and compact mechanical design. Given an electrode configuration, we can design an analog backplane in such a way that both current injections and voltage measurements can be done without using any switch. The KHU Mark2 is based on an impedance measurement module (IMM) comprising a current source and a voltmeter. Using multiple IMMs, we can construct a multi-channel system with 16, 32 or 64 channels, for example. Adopting a pipeline structure, it has the maximum data acquisition speed of 100 scans s(-1) with the potential to detect fast physiological changes during respiration and cardiac activity. Measuring both in-phase and quadrature components of trans-impedances at multiple frequencies simultaneously, the KHU Mark2 is apt at spectroscopic EIT imaging. In this paper, we describe its design, construction, calibration and performance evaluation. It has about 84 dB signal-to-noise ratio and 0.5% reciprocity error. Time-difference images of an admittivity phantom are presented showing spectroscopic admittivity images. Future application studies using the KHU Mark2 are briefly discussed. PMID:21646706

  14. THE DOUBLE PULSAR ECLIPSES. I. PHENOMENOLOGY AND MULTI-FREQUENCY ANALYSIS

    SciTech Connect

    Breton, R. P.; Kaspi, V. M.; McLaughlin, M. A.; Lyutikov, M.; Kramer, M.; Stairs, I. H.; Ransom, S. M.; Ferdman, R. D.; Camilo, F.; Possenti, A.

    2012-03-10

    The double pulsar PSR J0737-3039A/B displays short, 30 s eclipses that arise around conjunction when the radio waves emitted by pulsar A are absorbed as they propagate through the magnetosphere of its companion pulsar B. These eclipses offer a unique opportunity to directly probe the magnetospheric structure and the plasma properties of pulsar B. We have performed a comprehensive analysis of the eclipse phenomenology using multi-frequency radio observations obtained with the Green Bank Telescope. We have characterized the periodic flux modulations previously discovered at 820 MHz by McLaughlin et al. and investigated the radio frequency dependence of the duration and depth of the eclipses. Based on their weak radio frequency evolution, we conclude that the plasma in pulsar B's magnetosphere requires a large multiplicity factor ({approx}10{sup 5}). We also found that, as expected, flux modulations are present at all radio frequencies in which eclipses can be detected. Their complex behavior is consistent with the confinement of the absorbing plasma in the dipolar magnetic field of pulsar B as suggested by Lyutikov and Thompson and such a geometric connection explains that the observed periodicity is harmonically related to pulsar B's spin frequency. We observe that the eclipses require a sharp transition region beyond which the plasma density drops off abruptly. Such a region defines a plasmasphere that would be well inside the magnetospheric boundary of an undisturbed pulsar. It is also two times smaller than the expected standoff radius calculated using the balance of the wind pressure from pulsar A and the nominally estimated magnetic pressure of pulsar B.

  15. Encoding Dictionaries.

    ERIC Educational Resources Information Center

    Ide, Nancy

    1995-01-01

    Describes problems in devising a Text Encoding Initiative (TEI) encoding format for dictionaries. Asserts that the high degree of structuring and compression of information are among the most complex text types treated in the TEI. Concludes that the source of some TEI problems lies in the design of Standard Generalized Markup Language (SGML). (CFR)

  16. Radio frequency current-voltage probe for impedance and power measurements in multi-frequency unmatched loads

    NASA Astrophysics Data System (ADS)

    Lafleur, T.; Delattre, P. A.; Booth, J. P.; Johnson, E. V.; Dine, S.

    2013-01-01

    A broad-band, inline current-voltage probe, with a characteristic impedance of 50 Ω, is presented for the measurement of voltage and current waveforms, impedance, and power in rf systems. The probe, which uses capacitive and inductive sensors to determine the voltage and current, respectively, can be used for the measurement of single or multi-frequency signals into both matched and unmatched loads, over a frequency range of about 1-100 MHz. The probe calibration and impedance/power measurement technique are described in detail, and the calibrated probe results are compared with those obtained from a vector network analyzer and other commercial power meters. Use of the probe is demonstrated with the measurement of power into an unmatched capacitively coupled plasma excited by multi-frequency tailored voltage waveforms.

  17. Radio frequency current-voltage probe for impedance and power measurements in multi-frequency unmatched loads.

    PubMed

    Lafleur, T; Delattre, P A; Booth, J P; Johnson, E V; Dine, S

    2013-01-01

    A broad-band, inline current-voltage probe, with a characteristic impedance of 50 Ω, is presented for the measurement of voltage and current waveforms, impedance, and power in rf systems. The probe, which uses capacitive and inductive sensors to determine the voltage and current, respectively, can be used for the measurement of single or multi-frequency signals into both matched and unmatched loads, over a frequency range of about 1-100 MHz. The probe calibration and impedance/power measurement technique are described in detail, and the calibrated probe results are compared with those obtained from a vector network analyzer and other commercial power meters. Use of the probe is demonstrated with the measurement of power into an unmatched capacitively coupled plasma excited by multi-frequency tailored voltage waveforms. PMID:23387681

  18. Multi-frequency monitoring of γ-ray loud blazars. I. Light curves and spectral energy distributions

    NASA Astrophysics Data System (ADS)

    Bach, U.; Raiteri, C. M.; Villata, M.; Fuhrmann, L.; Buemi, C. S.; Larionov, V. M.; Letog, P.; Arkharov, A. A.; Coloma, J. M.; di Paola, A.; Dolci, M.; Efimova, N.; Forné, E.; Ibrahimov, M. A.; Hagen-Thorn, V.; Konstantinova, T.; Kopatskaya, E.; Lanteri, L.; Kurtanidze, O. M.; Maccaferri, G.; Nikolashvili, M. G.; Orlati, A.; Ros, J. A.; Tosti, G.; Trigilio, C.; Umana, G.

    2007-03-01

    Context: Being dominated by non-thermal emission from aligned relativistic jets, blazars allow us to elucidate the physics of extragalactic jets, and, ultimately, how the energy is extracted from the central black hole in radio-loud active galactic nuclei. Aims: Crucial information is provided by broad-band spectral energy distributions (SEDs), their trends with luminosity and correlated multi-frequency variability. With this study we plan to obtain a database of contemporaneous radio-to-optical spectra of a sample of blazars, which are and will be observed by current and future high-energy satellites. Methods: Since December 2004 we are performing a monthly multi-frequency radio monitoring of a sample of 35 blazars at the antennas in Medicina and Noto. Contemporaneous near-IR and optical observations for all our observing epochs are organised. Results: Until June 2006 about 4000 radio measurements and 5500 near-IR and optical measurements were obtained. Most of the sources show significant variability in all observing bands. Here we present the multi-frequency data acquired during the first eighteen months of the project, and construct the SEDs for the best-sampled sources.

  19. A robust multi-frequency mixing algorithm for suppression of rivet signal in GMR inspection of riveted structures

    NASA Astrophysics Data System (ADS)

    Safdernejad, Morteza S.; Karpenko, Oleksii; Ye, Chaofeng; Udpa, Lalita; Udpa, Satish

    2016-02-01

    The advent of Giant Magneto-Resistive (GMR) technology permits development of novel highly sensitive array probes for Eddy Current (EC) inspection of multi-layer riveted structures. Multi-frequency GMR measurements with different EC pene-tration depths show promise for detection of bottom layer notches at fastener sites. However, the distortion of the induced magnetic field due to flaws is dominated by the strong fastener signal, which makes defect detection and classification a challenging prob-lem. This issue is more pronounced for ferromagnetic fasteners that concentrate most of the magnetic flux. In the present work, a novel multi-frequency mixing algorithm is proposed to suppress rivet signal response and enhance defect detection capability of the GMR array probe. The algorithm is baseline-free and does not require any assumptions about the sample geometry being inspected. Fastener signal suppression is based upon the random sample consensus (RANSAC) method, which iteratively estimates parameters of a mathematical model from a set of observed data with outliers. Bottom layer defects at fastener site are simulated as EDM notches of different length. Performance of the proposed multi-frequency mixing approach is evaluated on finite element data and experimental GMR measurements obtained with unidirectional planar current excitation. Initial results are promising demonstrating the feasibility of the approach.

  20. Effects of multi-frequency power ultrasound on the enzymolysis and structural characteristics of corn gluten meal.

    PubMed

    Jin, Jian; Ma, Haile; Wang, Kai; Yagoub, Abu El-Gasim A; Owusu, John; Qu, Wenjuan; He, Ronghai; Zhou, Cunshan; Ye, Xiaofei

    2015-05-01

    The aim of this study was to investigate the effect of multi-frequency power ultrasound (sweeping frequency and pulsed ultrasound (SFPU) and sequential dual frequency ultrasound (SDFU)) on the enzymolysis of corn gluten meal (CGM) and on the structures of the major protein fractions (zein, glutelin) of CGM. The results showed that multi-frequency power ultrasound pretreatments improved significantly (P<0.05) the degree of hydrolysis and conversion rate of CGM. The changes in UV-Vis spectra, fluorescence emission spectra, surface hydrophobicity (H0), and the content of SH and SS groups indicated unfolding of zein and glutelin by ultrasound. The circular dichroism analysis showed that both pretreatments decreased α-helix and increased β-sheet of glutelin. The SFPU pretreatment had little impact on the secondary structure of zein, while the SDFU increased the α-helix and decreased the β-sheet remarkably. Scanning electron microscope indicated that both pretreatments destroyed the microstructures of glutelin and CGM, reduced the particle size of zein despite that the SDFU induced aggregation was observed. In conclusion, multi-frequency power ultrasound pretreatment is an efficient method in protein proteolysis due to its sonochemistry effect on the molecular conformation as well as on the microstructure of protein. PMID:25577971

  1. Multi-frequency survey of background radiations of the Universe. The "Cosmological Gene" project. First results

    NASA Astrophysics Data System (ADS)

    Parijskij, Yu. N.; Mingaliev, M. G.; Nizhel'Skii, N. A.; Bursov, N. N.; Berlin, A. B.; Grechkin, A. A.; Zharov, V. I.; Zhekanis, G. V.; Majorova, E. K.; Semenova, T. A.; Stolyarov, V. A.; Tsybulev, P. G.; Kratov, D. V.; Udovitskii, R. Yu.; Khaikin, V. B.

    2011-10-01

    The results of the first stage of the "Cosmological Gene" project of the Russian Academy of Sciences are reported. These results consist in the accumulation of multi-frequency data in 31 frequency channels in the wavelength interval 1-55 cm with maximum achievable statistical sensitivity limited by the noise of background radio sources at all wavelengths exceeding 1.38 cm. The survey region is determined by constraints 00 h < RA < 24 h and 40°30' < DEC < 42°30'. The scientific goals of the project are refined in view of recent proposals to use cosmological background radiation data for the development of a unified physical theory. Experimental data obtained with the RATAN-600 radio telescope are used to refine the contribution of the main "screens" located between the observer and the formation epoch of cosmic background radiation ( z = 1100). Experimental data for synchrotron radiation and free-free noise on scales that are of interest for the anisotropy of cosmic microwave background are reported as well as the contribution of these noise components in millimeter-wave experiments to be performed in the nearest years. The role of dipole radio emission of fullerene-type dust nanostructures is shown to be small. The most precise estimates of the role of background radio sources with inverted spectra are given and these sources are shown to create no serious interference in experiments. The average spectral indices of the weakest sources of the NVSS and FIRST catalogs are estimated. The "saturation" data for all wavelengths allowed a constraint to be imposed on the Sunyaev-Zeldovich noise (the SZ noise) at all wavelengths, and made it possible to obtain independent estimates of the average sky temperature from sources, substantially weaker than those listed in the NVSS catalog. These estimates are inconsistent with the existence of powerful extragalactic synchrotron background associated with radio sources. Appreciable "quadrupole" anisotropy in is detected in the

  2. Land subsidence in the Yangtze River Delta, China revealed from multi-frequency SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Li, Zhenhong; Motagh, Mahdi; Yu, Jun; Gong, Xulong; Wu, Jianqiang; Zhu, Yefei; Chen, Huogen; Zhang, Dengming; Xu, Yulin

    2014-05-01

    of multi-frequency SAR datasets allows a long record (~20 years) of historic deformation to be measured over a large region. Ultimately this should help inform land managers in assessing land subsidence and planning appropriate remedial measures.

  3. Experimental research of the Multi-frequency Acoustic Backscatter System using the field sediment

    NASA Astrophysics Data System (ADS)

    Zhang, wenxiang

    2014-05-01

    The measurements of suspended sediment concentration and particle size profiles are very important to the engineering and environmental applications, especially in the estuarine and coastal areas. In recent years acoustic method has obtained increasing acceptance by many researchers. The theory of this method for measuring them is based on the acoustic backscattering and attenuation properties of the sediment in suspension. The Multi-frequency Acoustic Backscatter System (MABS), which has four acoustic sensors with different frequencies, can be measuring the profiles in the shallow water environment (no more than 10 meters). The experiments were conducted for AQUAscat1000 (MABS) (Made in UK) by the 'test tower' (φ600mm by 1500mm) in Laboratory. The frequency of the acoustic transducer is 0.5MHz, 1MHz, 2MHz and 4MHz, respectively. Two different places sediment were obtained from the Yangtze estuary. The average particle size is about 15μm and 115μm, respectively. Suspended sediment concentration in the 'test tower' was relatively constant during each phase of the sampling. The experimental procedures were as follows: (1) obtaining the background value of the instrument system; (2) add the field sediment to the tower according to the weight and allowing the mixture to homogenize; (3) obtaining water samples in different depths from the 'test tower'; (4) analyzing the water samples. These preliminary results show that (1) the MABS sensors are estimated from a complex function, depending on the receiving information (Voltage), measured at range, the speed of sound in water and the attenuation of sound by water, the sediment density and radius, and backscattering property of the sediment; (2) the appropriate calibration and regression approaches should be selected so as to obtain the reliable results of suspended sediment concentration(**R2 >0.7) and particle size(**R2 >0.5) measurements; (3) the MABS could be applied in the relative fine sediment condition, and

  4. Deciphering ENCODE.

    PubMed

    Diehl, Adam G; Boyle, Alan P

    2016-04-01

    The ENCODE project represents a major leap from merely describing and comparing genomic sequences to surveying them for direct indicators of function. The astounding quantity of data produced by the ENCODE consortium can serve as a map to locate specific landmarks, guide hypothesis generation, and lead us to principles and mechanisms underlying genome biology. Despite its broad appeal, the size and complexity of the repository can be intimidating to prospective users. We present here some background about the ENCODE data, survey the resources available for accessing them, and describe a few simple principles to help prospective users choose the data type(s) that best suit their needs, where to get them, and how to use them to their best advantage. PMID:26962025

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

    NASA Astrophysics Data System (ADS)

    Jiang, Kejian; Zhu, Changsheng

    2011-05-01

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

  6. Multi-frequency force-detected electron spin resonance in the millimeter-wave region up to 150 GHz

    NASA Astrophysics Data System (ADS)

    Ohmichi, E.; Tokuda, Y.; Tabuse, R.; Tsubokura, D.; Okamoto, T.; Ohta, H.

    2016-07-01

    In this article, a novel technique is developed for multi-frequency force-detected electron spin resonance (ESR) in the millimeter-wave region. We constructed a compact ESR probehead, in which the cantilever bending is sensitively detected by a fiber-optic Fabry-Perot interferometer. With this setup, ESR absorption of diphenyl-picrylhydrazyl radical (<1 μg) was clearly observed at multiple frequencies of up to 150 GHz. We also observed the hyperfine splitting of low-concentration Mn2+ impurities(˜0.2%) in MgO.

  7. Multi-frequency force-detected electron spin resonance in the millimeter-wave region up to 150 GHz.

    PubMed

    Ohmichi, E; Tokuda, Y; Tabuse, R; Tsubokura, D; Okamoto, T; Ohta, H

    2016-07-01

    In this article, a novel technique is developed for multi-frequency force-detected electron spin resonance (ESR) in the millimeter-wave region. We constructed a compact ESR probehead, in which the cantilever bending is sensitively detected by a fiber-optic Fabry-Perot interferometer. With this setup, ESR absorption of diphenyl-picrylhydrazyl radical (<1 μg) was clearly observed at multiple frequencies of up to 150 GHz. We also observed the hyperfine splitting of low-concentration Mn(2+) impurities(∼0.2%) in MgO. PMID:27475568

  8. Retrieving small features in reflection-mode raster-scan optoacoustic mesoscopy (RSOM) using multi-frequency reconstruction

    NASA Astrophysics Data System (ADS)

    Omar, Murad; Soliman, Dominik; Gateau, Jérôme; Ntziachristos, Vasilis

    2015-03-01

    We developed a reflection-mode, raster-scan optoacoustic mesoscopy system, based on a custom-made ultrasonic detector, with an ultra wide bandwidth of 20-180 MHz. To optimally use this bandwidth, we implemented multifrequency reconstruction. System characterization reveals a 4 μm axial, and 18 μm transverse resolution, at penetration depths reaching 5 mm. After characterization, the system was applied to image a zebrafish ex vivo, and an excised mouse ear. In the zebrafish, the lateral line, intestines, eyes, and melanocytes are seen, while in the mouse ear, multi-frequency reconstruction recovered the small vessels, otherwise not seen on the image.

  9. Evaluation of Long-Term Cloud-Resolving Model Simulations Using Satellite Radiance Observations and Multi-Frequency Satellite Simulators

    NASA Technical Reports Server (NTRS)

    Matsui, Toshihisa; Zeng, Xiping; Tao, Wei-Kuo; Masunaga, Hirohiko; Olson, William S.; Lang, Stephen

    2008-01-01

    This paper proposes a methodology known as the Tropical Rainfall Measuring Mission (TRMM) Triple-Sensor Three-step Evaluation Framework (T3EF) for the systematic evaluation of precipitating cloud types and microphysics in a cloud-resolving model (CRM). T3EF utilizes multi-frequency satellite simulators and novel statistics of multi-frequency radiance and backscattering signals observed from the TRMM satellite. Specifically, T3EF compares CRM and satellite observations in the form of combined probability distributions of precipitation radar (PR) reflectivity, polarization-corrected microwave brightness temperature (Tb), and infrared Tb to evaluate the candidate CRM. T3EF is used to evaluate the Goddard Cumulus Ensemble (GCE) model for cases involving the South China Sea Monsoon Experiment (SCSMEX) and Kwajalein Experiment (KWAJEX). This evaluation reveals that the GCE properly captures the satellite-measured frequencies of different precipitating cloud types in the SCSMEX case but underestimates the frequencies of deep convective and deep stratiform types in the KWAJEX case. Moreover, the GCE tends to simulate excessively large and abundant frozen condensates in deep convective clouds as inferred from the overestimated GCE-simulated radar reflectivities and microwave Tb depressions. Unveiling the detailed errors in the GCE s performance provides the best direction for model improvements.

  10. Using multi-frequency acoustic attenuation to monitor grain size and concentration of suspended sediment in rivers.

    PubMed

    Moore, S A; Le Coz, J; Hurther, D; Paquier, A

    2013-04-01

    Multi-frequency acoustic backscatter profiles recorded with side-looking acoustic Doppler current profilers are used to monitor the concentration and size of sedimentary particles suspended in fluvial environments. Data at 300, 600, and 1200 kHz are presented from the Isère River in France where the dominant particles in suspension are silt and clay sizes. The contribution of suspended sediment to the through-water attenuation was determined for three high concentration (> 100 mg/L) events and compared to theoretical values for spherical particles having size distributions that were measured by laser diffraction in water samples. Agreement was good for the 300 kHz data, but it worsened with increasing frequency. A method for the determination of grain size using multi-frequency attenuation data is presented considering models for spherical and oblate spheroidal particles. When the resulting size estimates are used to convert sediment attenuation to concentration, the spheroidal model provides the best agreement with optical estimates of concentration, but the aspect ratio and grain size that provide the best fit differ between events. The acoustic estimates of size were one-third the values from laser grain sizing. This agreement is encouraging considering optical and acoustical instruments measure different parameters. PMID:23556566

  11. Ultra-broadband phase-sensitive optical time-domain reflectometry with a temporally sequenced multi-frequency source.

    PubMed

    Wang, Zhaoyong; Pan, Zhengqing; Fang, Zujie; Ye, Qing; Lu, Bin; Cai, Haiwen; Qu, Ronghui

    2015-11-15

    A phase-sensitive optical time-domain reflectometry (Φ-OTDR) with a temporally sequenced multi-frequency (TSMF) source is proposed. This technique can improve the system detection bandwidth without the sensing range decreasing. Up to 0.5 MHz detection bandwidth over 9.6 km is experimentally demonstrated as an example. To the best of our knowledge, this is the first time that such a high detection bandwidth over such a long sensing range is reported in Φ-OTDR-based distributed vibration sensing. The technical issues of TSMF Φ-OTDR are discussed in this Letter. This technique will help Φ-OTDR find new important foreground in long-haul distributed broadband-detection applications, such as structural-health monitoring and partial-discharge online monitoring of high voltage power cables. PMID:26565832

  12. Ion beams extraction and measurements of plasma parameters on a multi-frequencies microwaves large bore ECRIS with permanent magnets

    SciTech Connect

    Nozaki, Dai; Kiriyama, Ryutaro; Takenaka, Tomoya; Kurisu, Yosuke; Yano, Keisuke; Sato, Fuminobu; Kato, Yushi; Iida, Toshiyuki

    2012-11-06

    We have developed an all-permanent magnet large bore electron cyclotron resonance ion source (ECRIS) for broad ion beam processing. The cylindrically comb-shaped magnetic field configuration is adopted for efficient plasma production and good magnetic confinement. To compensate for disadvantages of fixed magnetic configuration, a traveling wave tube amplifier (TWTA) is used. In the comb-shaped ECRIS, it is difficult to achieve controlling ion beam profiles in the whole inside the chamber by using even single frequency-controllable TWTA (11-13GHz), because of large bore size with all-magnets. We have tried controlling profiles of plasma parameters and then those of extracted ion beams by launching two largely different frequencies simultaneously, i.e., multi-frequencies microwaves. Here we report ion beam profiles and corresponding plasma parameters under various experimental conditions, dependence of ion beams against extraction voltages, and influence of different electrode positions on the electron density profile.

  13. Comparison Of Multi-Frequency SAR Land Cover Signatures For Multi-Site Semi-Arid Regions Of Africa

    NASA Astrophysics Data System (ADS)

    Spies, Bernard; Lamb, Alistair; Brown, Sarah, Balzter, Heiko; Fisher, Peter

    2013-12-01

    This study shows the analysis and comparison of different SAR backscatter signatures (σ0 distributions) for distinguishable land cover types over two semi-arid test sites in Africa. The two sites that were chosen are located in Tanzania and Chad, where existing multi- frequency data was available from the different synthetic aperture radar (SAR) archives. Images were grouped into wet and dry season for the Tanzania site, whereas only dry season imagery was available for the Chad site. An IsoData unsupervised classification was applied on all three sets of images to classify seven land cover classes. Random samples were taken from each of the classes, resulting in σ0 distributions for the different classes for each site. These SAR land cover signatures are interpreted and discussed, with further steps identified.

  14. Mapping power-law rheology of living cells using multi-frequency force modulation atomic force microscopy

    SciTech Connect

    Takahashi, Ryosuke; Okajima, Takaharu

    2015-10-26

    We present multi-frequency force modulation atomic force microscopy (AFM) for mapping the complex shear modulus G* of living cells as a function of frequency over the range of 50–500 Hz in the same measurement time as the single-frequency force modulation measurement. The AFM technique enables us to reconstruct image maps of rheological parameters, which exhibit a frequency-dependent power-law behavior with respect to G{sup *}. These quantitative rheological measurements reveal a large spatial variation in G* in this frequency range for single cells. Moreover, we find that the reconstructed images of the power-law rheological parameters are much different from those obtained in force-curve or single-frequency force modulation measurements. This indicates that the former provide information about intracellular mechanical structures of the cells that are usually not resolved with the conventional force measurement methods.

  15. Wired/wireless access integrated RoF-PON with scalable generation of multi-frequency MMWs enabled by polarization multiplexed FWM in SOA.

    PubMed

    Xiang, Yu; Chen, Chen; Zhang, Chongfu; Qiu, Kun

    2013-01-14

    In this paper, we propose and demonstrate a novel integrated radio-over-fiber passive optical network (RoF-PON) system for both wired and wireless access. By utilizing the polarization multiplexed four-wave mixing (FWM) effect in a semiconductor optical amplifier (SOA), scalable generation of multi-frequency millimeter-waves (MMWs) can be provided so as to assist the configuration of multi-frequency wireless access for the wire/wireless access integrated ROF-PON system. In order to obtain a better performance, the polarization multiplexed FWM effect is investigated in detail. Simulation results successfully verify the feasibility of our proposed scheme. PMID:23389014

  16. The Multi-Frequency Correlation Between Eua and sCER Futures Prices: Evidence from the Emd Approach

    NASA Astrophysics Data System (ADS)

    Zhang, Yue-Jun; Huang, Yi-Song

    2015-05-01

    Currently European Union Allowances (EUA) and secondary Certified Emission Reduction (sCER) have become two dominant carbon trading assets for investors and their linkage attracts much attention from academia and practitioners in recent years. Under this circumstance, we use the empirical mode decomposition (EMD) approach to decompose the two carbon futures contract prices and discuss their correlation from the multi-frequency perspective. The empirical results indicate that, first, the EUA and sCER futures price movements can be divided into those triggered by the long-term, medium-term and short-term market impacts. Second, the price movements in the EUA and sCER futures markets are primarily caused by the long-term impact, while the short-term impact can only explain a small fraction. Finally, the long-term (short-term) effect on EUA prices is statistically uncorrelated with the short-term (long-term) effect of sCER prices, and there is a medium or strong lead-and-lag correlation between the EUA and sCER price components with the same time scales. These results may provide some important insights of price forecast and arbitraging activities for carbon futures market investors, analysts and regulators.

  17. Towards a reference cavitating vessel Part III—design and acoustic pressure characterization of a multi-frequency sonoreactor

    NASA Astrophysics Data System (ADS)

    Wang, Lian; Memoli, Gianluca; Hodnett, Mark; Butterworth, Ian; Sarno, Dan; Zeqiri, Bajram

    2015-08-01

    A multi-frequency cavitation vessel (RV-multi) has been commissioned at the National Physical Laboratory (NPL, UK), with the aim of establishing a standard source of acoustic cavitation in water, with reference to which details of the cavitation process can be studied and cavitation measurement techniques evaluated. The vessel is a cylindrical cavity with a maximum capacity up to 17 L, and is designed to work at six frequency ranges, from 21 kHz to 136 kHz, under controlled temperature conditions. This paper discusses the design of RV-multi and reports experiments carried out to establish the reproducibility of the acoustic pressure field established within the vessel and its operating envelope, including sensitivity to aspects such as water depth and temperature. The acoustic field distribution was determined along the radial and depth directions within the vessel using a miniature hydrophone, for two input voltage levels under low power transducer excitation conditions (e.g. below the cavitation threshold). Particular care was taken in determining peak acoustic pressure locations, as these are critical for accompanying cavitation studies. Perturbations of the vessel by the measuring hydrophone were also monitored with a bottom-mounted pressure sensor.

  18. Development of a multi-frequency diffuse photon density wave device for the characterization of tissue damage at multiple depths

    NASA Astrophysics Data System (ADS)

    Diaz, David; Weingarten, Michael S.; Neidrauer, Michael T.; Samuels, Joshua A.; Huneke, Richard B.; Kuzmin, Vladimir L.; Lewin, Peter A.; Zubkov, Leonid A.

    2014-02-01

    The ability to determine the depth and degree of cutaneous and subcutaneous tissue damage is critical for medical applications such as burns and pressure ulcers. The Diffuse Photon Density Wave (DPDW) methodology at near infrared wavelengths can be used to non-invasively measure the optical absorption and reduced scattering coefficients of tissue at depths of several millimeters. A multi-frequency DPDW system with one light source and one detector was constructed so that light is focused onto the tissue surface using an optical fiber and lens mounted to a digitally-controlled actuator which changes the distance between light source and detector. A variable RF generator enables the modulation frequency to be selected between 50 to 400MHz. The ability to digitally control both source-detector separation distance and modulation frequency allows for virtually unlimited number of data points, enabling precise selection of the volume and depth of tissue that will be characterized. Suspensions of Intralipid and india ink with known absorption and reduced scattering coefficients were used as optical phantoms to assess device accuracy. Solid silicon phantoms were formulated for stability testing. Standard deviations for amplitude and phase shift readings were found to be 0.9% and 0.2 degrees respectively, over a one hour period. The ability of the system to quantify tissue damage in vivo at multiple depths was tested in a porcine burn model.

  19. A quick and easy method for checking compliance of multi-frequency magnetic fields with ICNIRP's guidelines.

    PubMed

    Filippopoulos, George; Karabetsos, Efthymios

    2008-08-01

    In many practical cases human exposure to extremely low frequency magnetic fields with many spectral components (multi-frequency fields) has to be examined in order to check compliance with ICNIRP's guidelines. Showing compliance, according to existing methods, requires sophisticated instruments and measurement procedures to assess some complex exposure metrics. Furthermore, even where the field levels are very low, there is no method to show compliance using broadband instruments, which are the most common and simple ones. In this paper, a new method is described where the frequencies emitted by the source are known and only simple broadband instruments are required. First, the spectral distribution of the field that maximizes exposure metrics is found. Then, an effective reference level for the broadband value of the field is estimated for this distribution. If the measured broadband value of the magnetic field is lower than this reference level, then compliance with ICNIRP's guidelines is readily shown. A case study for a magnetic field consisting of 50 Hz and 60 Hz components is presented. The worst-case spectral distribution contained 64% 50 Hz and 76.8% 60 Hz components, and the corresponding effective broadband reference level is 64 muT for general public exposure. The method is generally conservative in cases of incoherent fields and very conservative in cases of coherent fields. To that end, it is practically a quick and easy test to check if further measurements are needed or not. Application of this method is expected to save time, money, and resources. PMID:18617807

  20. System Description and First Application of an FPGA-Based Simultaneous Multi-Frequency Electrical Impedance Tomography.

    PubMed

    Aguiar Santos, Susana; Robens, Anne; Boehm, Anna; Leonhardt, Steffen; Teichmann, Daniel

    2016-01-01

    A new prototype of a multi-frequency electrical impedance tomography system is presented. The system uses a field-programmable gate array as a main controller and is configured to measure at different frequencies simultaneously through a composite waveform. Both real and imaginary components of the data are computed for each frequency and sent to the personal computer over an ethernet connection, where both time-difference imaging and frequency-difference imaging are reconstructed and visualized. The system has been tested for both time-difference and frequency-difference imaging for diverse sets of frequency pairs in a resistive/capacitive test unit and in self-experiments. To our knowledge, this is the first work that shows preliminary frequency-difference images of in-vivo experiments. Results of time-difference imaging were compared with simulation results and shown that the new prototype performs well at all frequencies in the tested range of 60 kHz-960 kHz. For frequency-difference images, further development of algorithms and an improved normalization process is required to correctly reconstruct and interpreted the resulting images. PMID:27463715

  1. Continuous-scanning laser Doppler vibrometry: Extensions to arbitrary areas, multi-frequency and 3D capture

    SciTech Connect

    Weekes, B.; Ewins, D.; Acciavatti, F.

    2014-05-27

    To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics.

  2. On the self-excitation mechanisms of plasma series resonance oscillations in single- and multi-frequency capacitive discharges

    SciTech Connect

    Schüngel, Edmund; Brandt, Steven; Schulze, Julian; Korolov, Ihor; Derzsi, Aranka; Donkó, Zoltán

    2015-04-15

    The self-excitation of plasma series resonance (PSR) oscillations is a prominent feature in the current of low pressure capacitive radio frequency discharges. This resonance leads to high frequency oscillations of the charge in the sheaths and enhances electron heating. Up to now, the phenomenon has only been observed in asymmetric discharges. There, the nonlinearity in the voltage balance, which is necessary for the self-excitation of resonance oscillations with frequencies above the applied frequencies, is caused predominantly by the quadratic contribution to the charge-voltage relation of the plasma sheaths. Using Particle In Cell/Monte Carlo collision simulations of single- and multi-frequency capacitive discharges and an equivalent circuit model, we demonstrate that other mechanisms, such as a cubic contribution to the charge-voltage relation of the plasma sheaths and the time dependent bulk electron plasma frequency, can cause the self-excitation of PSR oscillations, as well. These mechanisms have been neglected in previous models, but are important for the theoretical description of the current in symmetric or weakly asymmetric discharges.

  3. Multi-frequency color-marked fringe projection profilometry for fast 3D shape measurement of complex objects.

    PubMed

    Jiang, Chao; Jia, Shuhai; Dong, Jun; Bao, Qingchen; Yang, Jia; Lian, Qin; Li, Dichen

    2015-09-21

    We propose a novel multi-frequency color-marked fringe projection profilometry approach to measure the 3D shape of objects with depth discontinuities. A digital micromirror device projector is used to project a color map consisting of a series of different-frequency color-marked fringe patterns onto the target object. We use a chromaticity curve to calculate the color change caused by the height of the object. The related algorithm to measure the height is also described in this paper. To improve the measurement accuracy, a chromaticity curve correction method is presented. This correction method greatly reduces the influence of color fluctuations and measurement error on the chromaticity curve and the calculation of the object height. The simulation and experimental results validate the utility of our method. Our method avoids the conventional phase shifting and unwrapping process, as well as the independent calculation of the object height required by existing techniques. Thus, it can be used to measure complex and dynamic objects with depth discontinuities. These advantages are particularly promising for industrial applications. PMID:26406621

  4. Continuous-scanning laser Doppler vibrometry: Extensions to arbitrary areas, multi-frequency and 3D capture

    NASA Astrophysics Data System (ADS)

    Weekes, B.; Ewins, D.; Acciavatti, F.

    2014-05-01

    To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics.

  5. MULTI-FREQUENCY STUDIES OF RADIO RELICS IN THE GALAXY CLUSTERS A4038, A1664, AND A786

    SciTech Connect

    Kale, Ruta; Dwarakanath, K. S.

    2012-01-01

    We present a multi-frequency study of radio relics associated with the galaxy clusters A4038, A1664, and A786. Radio images, integrated spectra, spectral index maps, and fits to the integrated spectra in the framework of the adiabatic compression model are presented. Images of the relic in A4038 at 150, 240, and 606 MHz with the Giant Meterwave Radio Telescope have revealed extended ultra-steep spectrum ({alpha} {approx} -1.8 to -2.7) emission of extent 210 Multiplication-Sign 80 kpc{sup 2}. The model of passively evolving radio lobes compressed by a shock fits the integrated spectrum best. The relic with a circular morphology at the outskirts of the cluster A1664 has an integrated spectral index of {approx} - 1.10 {+-} 0.06 and is best fit by the model of radio lobes lurking for {approx}4 Multiplication-Sign 10{sup 7} yr. The relic near A786 has a curved spectrum and is best fit by a model of radio lobes lurking for {approx}3 Multiplication-Sign 10{sup 7} yr. At 4.7 GHz, a compact radio source, possibly the progenitor of the A786 relic, is detected near the center of the radio relic. The A786 radio relic is thus likely a lurking radio galaxy rather than a site of cosmological shock as has been considered in earlier studies.

  6. Non-contact multi-frequency magnetic induction spectroscopy system for industrial-scale bio-impedance measurement

    NASA Astrophysics Data System (ADS)

    O'Toole, M. D.; Marsh, L. A.; Davidson, J. L.; Tan, Y. M.; Armitage, D. W.; Peyton, A. J.

    2015-03-01

    Biological tissues have a complex impedance, or bio-impedance, profile which changes with respect to frequency. This is caused by dispersion mechanisms which govern how the electromagnetic field interacts with the tissue at the cellular and molecular level. Measuring the bio-impedance spectra of a biological sample can potentially provide insight into the sample’s properties and its cellular structure. This has obvious applications in the medical, pharmaceutical and food-based industrial domains. However, measuring the bio-impedance spectra non-destructively and in a way which is practical at an industrial scale presents substantial challenges. The low conductivity of the sample requires a highly sensitive instrument, while the demands of industrial-scale operation require a fast high-throughput sensor of rugged design. In this paper, we describe a multi-frequency magnetic induction spectroscopy (MIS) system suitable for industrial-scale, non-contact, spectroscopic bio-impedance measurement over a bandwidth of 156 kHz-2.5 MHz. The system sensitivity and performance are investigated using calibration and known reference samples. It is shown to yield rapid and consistently sensitive results with good long-term stability. The system is then used to obtain conductivity spectra of a number of biological test samples, including yeast suspensions of varying concentration and a range of agricultural produce, such as apples, pears, nectarines, kiwis, potatoes, oranges and tomatoes.

  7. Joint inversion of Multi-frequency Electromagnetic Induction and Seismic Refraction Data For Improved Near Surface Characterization

    NASA Astrophysics Data System (ADS)

    Elwaseif, M.

    2015-12-01

    We present a joint inversion routine between multi-frequency Electromagnetic (EM) induction and seismic refraction data that is based on using both cross-gradients and disconnect constraints. The joint inverse problem was solved using an iterative nonlinear least-squares formulation. Following each iteration, the cross gradient constraint enforces structural similarities between the EM and seismic models, whereas the disconnect constraint enforces sharp boundaries between different strata within the EM model. The locations of boundaries within the EM model are assumed to be consistent with the locations of user-defined velocity contours in the seismic model. We tested our method on a challenging synthetic EM and seismic model scenario that contains water-bearing zones as well as positively and negatively correlated model parameter values. In addition, we applied our method to GEM-2 and seismic refraction field data sets acquired along a 28-m-long profile in Laramie (WY), and we precisely recorded the locations where ground surface resistivity and velocity likely changes along that line. Unlike the results of separate EM and seismic inversions and the results of joint inversion based only on a cross-gradient constraint, our method was able to detect the water-bearing zones. In addition, it better captured ground surface changes in the field data set.

  8. Development of multi-frequency ESR system for high-pressure measurements up to 2.5 GPa

    NASA Astrophysics Data System (ADS)

    Sakurai, T.; Fujimoto, K.; Matsui, R.; Kawasaki, K.; Okubo, S.; Ohta, H.; Matsubayashi, K.; Uwatoko, Y.; Tanaka, H.

    2015-10-01

    A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10 T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S = 1 system with the single ion anisotropy NiSnCl6 · 6H2O and the S = 1 / 2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully.

  9. Synergistic multi-sensor and multi-frequency retrieval of cloud ice water path constrained by CloudSat collocations

    NASA Astrophysics Data System (ADS)

    Islam, Tanvir; Srivastava, Prashant K.

    2015-08-01

    The cloud ice water path (IWP) is one of the major parameters that have a strong influence on earth's radiation budget. Onboard satellite sensors are recognized as valuable tools to measure the IWP in a global scale. Albeit, active sensors such as the Cloud Profiling Radar (CPR) onboard the CloudSat satellite has better capability to measure the ice water content profile, thus, its vertical integral, IWP, than any passive microwave (MW) or infrared (IR) sensors. In this study, we investigate the retrieval of IWP from MW and IR sensors, including AMSU-A, MHS, and HIRS instruments on-board the N19 satellite, such that the retrieval is consistent with the CloudSat IWP estimates. This is achieved through the collocations between the passive satellite measurements and CloudSat scenes. Potential benefit of synergistic multi-sensor multi-frequency retrieval is investigated. Two modeling approaches are explored for the IWP retrieval - generalized linear model (GLM) and neural network (NN). The investigation has been carried out over both ocean and land surface types. The MW/IR synergy is found to be retrieved more accurate IWP than the individual AMSU-A, MHS, or HIRS measurements. Both GLM and NN approaches have been able to exploit the synergistic retrievals.

  10. Multi-frequency and polarimetric radar backscatter signatures for discrimination between agricultural crops at the Flevoland experimental test site

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Villasenor, J.; Klein, J. D.

    1991-01-01

    We describe the calibration and analysis of multi-frequency, multi-polarization radar backscatter signatures over an agriculture test site in the Netherlands. The calibration procedure involved two stages: in the first stage, polarimetric and radiometric calibrations (ignoring noise) were carried out using square-base trihedral corner reflector signatures and some properties of the clutter background. In the second stage, a novel algorithm was used to estimate the noise level in the polarimetric data channels by using the measured signature of an idealized rough surface with Bragg scattering (the ocean in this case). This estimated noise level was then used to correct the measured backscatter signatures from the agriculture fields. We examine the significance of several key parameters extracted from the calibrated and noise-corrected backscatter signatures. The significance is assessed in terms of the ability to uniquely separate among classes from 13 different backscatter types selected from the test site data, including eleven different crops, one forest and one ocean area. Using the parameters with the highest separation for a given class, we use a hierarchical algorithm to classify the entire image. We find that many classes, including ocean, forest, potato, and beet, can be identified with high reliability, while the classes for which no single parameter exhibits sufficient separation have higher rates of misclassification. We expect that modified decision criteria involving simultaneous consideration of several parameters increase performance for these classes.

  11. Performance assessment of multi-frequency processing of ICU chest images for enhanced visualization of tubes and catheters

    NASA Astrophysics Data System (ADS)

    Wang, Xiaohui; Couwenhoven, Mary E.; Foos, David H.; Doran, James; Yankelevitz, David F.; Henschke, Claudia I.

    2008-03-01

    An image-processing method has been developed to improve the visibility of tube and catheter features in portable chest x-ray (CXR) images captured in the intensive care unit (ICU). The image-processing method is based on a multi-frequency approach, wherein the input image is decomposed into different spatial frequency bands, and those bands that contain the tube and catheter signals are individually enhanced by nonlinear boosting functions. Using a random sampling strategy, 50 cases were retrospectively selected for the study from a large database of portable CXR images that had been collected from multiple institutions over a two-year period. All images used in the study were captured using photo-stimulable, storage phosphor computed radiography (CR) systems. Each image was processed two ways. The images were processed with default image processing parameters such as those used in clinical settings (control). The 50 images were then separately processed using the new tube and catheter enhancement algorithm (test). Three board-certified radiologists participated in a reader study to assess differences in both detection-confidence performance and diagnostic efficiency between the control and test images. Images were evaluated on a diagnostic-quality, 3-megapixel monochrome monitor. Two scenarios were studied: the baseline scenario, representative of today's workflow (a single-control image presented with the window/level adjustments enabled) vs. the test scenario (a control/test image pair presented with a toggle enabled and the window/level settings disabled). The radiologists were asked to read the images in each scenario as they normally would for clinical diagnosis. Trend analysis indicates that the test scenario offers improved reading efficiency while providing as good or better detection capability compared to the baseline scenario.

  12. Forming Super-Massive Black Hole Seeds under the Influence of a Nearby Anisotropic Multi-Frequency Source

    NASA Astrophysics Data System (ADS)

    Regan, John A.; Johansson, Peter H.; Wise, John H.

    2016-04-01

    The photo-dissociation of {H_2} by a nearby anisotropic source of radiation is seen as a critical component in creating an environment in which a direct collapse black hole may form. Employing radiative transfer we model the effect of multi-frequency (0.76 eV - 60 eV) radiation on a collapsing halo at high redshift. We vary both the shape of the spectrum which emits the radiation and the distance to the emitting galaxy. We use blackbody spectra with temperatures of {T = 10^4 K} and {T = 10^5 K} and a realistic stellar spectrum. We find that an optimal zone exists between 1 kpc and 4 kpc from the emitting galaxy. If the halo resides too close to the emitting galaxy the photo-ionising radiation creates a large HII region which effectively disrupts the collapsing halo, too far from the source and the radiation flux drops below the level of the expected background and the {H_2} fraction remains too high. When the emitting galaxy is initially placed between 1 kpc and 2 kpc from the collapsing halo, with a spectral shape consistent with a star-forming high redshift galaxy, then a large central core forms. The mass of the central core is between 5000 and 10000 M_{⊙}at a temperature of approximately 1000 K. This core is however surrounded by a reservoir of hotter gas at approximately 8000 K which leads to mass inflow rates of the order of ˜0.1 M_{⊙} yr-1.

  13. Effects of multi-frequency power ultrasound on the enzymolysis of corn gluten meal: Kinetics and thermodynamics study.

    PubMed

    Jin, Jian; Ma, Haile; Qu, Wenjuan; Wang, Kai; Zhou, Cunshan; He, Ronghai; Luo, Lin; Owusu, John

    2015-11-01

    The effects of multi-frequency power ultrasound (MPU) pretreatment on the kinetics and thermodynamics of corn gluten meal (CGM) were investigated in this research. The apparent constant (KM), apparent break-down rate constant (kA), reaction rate constants (k), energy of activation (Ea), enthalpy of activation (ΔH), entropy of activation (ΔS) and Gibbs free energy of activation (ΔG) were determined by means of the Michaelis-Menten equation, first-order kinetics model, Arrhenius equation and transition state theory, respectively. The results showed that MPU pretreatment can accelerate the enzymolysis of CGM under different enzymolysis conditions, viz. substrate concentration, enzyme concentration, pH, and temperature. Kinetics analysis revealed that MPU pretreatment decreased the KM value by 26.1% and increased the kA value by 7.3%, indicating ultrasound pretreatment increased the affinity between enzyme and substrate. In addition, the values of k for ultrasound pretreatment were increased by 84.8%, 41.9%, 28.9%, and 18.8% at the temperature of 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased Ea, ΔH and ΔS by 23.0%, 24.3% and 25.3%, respectively, but ultrasound had little change in ΔG value in the temperature range of 293-323 K. In conclusion, MPU pretreatment could remarkably enhance the enzymolysis of CGM, and this method can be applied to protein proteolysis industry to produce peptides. PMID:26186819

  14. Field test of a multi-frequency electromagnetic induction sensor for soil moisture monitoring in southern Italy test sites

    NASA Astrophysics Data System (ADS)

    Calamita, G.; Perrone, A.; Brocca, L.; Onorati, B.; Manfreda, S.

    2015-10-01

    Soil moisture is a variable of paramount importance for a number of natural processes and requires the capacity to be routinely measured at different spatial and temporal scales (e.g., hillslope and/or small catchment scale). The electromagnetic induction (EMI) method is one of the geophysical techniques potentially useful in this regard. Indeed, it does not require contact with the ground, it allows a relatively fast survey of hillslope, it gives information related to soil depth greater than few centimetres and it can also be used in wooded areas. In this study, apparent electrical conductivity (ECa) and soil moisture (SM) measurements were jointly carried out by using a multi-frequency EMI sensor (GEM-300) and Time Domain Reflectometry (TDR) probes, respectively. The aim was to retrieve SM variations at the hillslope scale over four sites, characterized by different land-soil units, located in a small mountainous catchment in southern Italy. Repeated measurements of ECa carried out over a fixed point showed that the signal variability of the GEM-300 sensor (Std. Err. ∼[0.02-0.1 mS/m]) was negligible. The correlation estimated between point ECa and SM, measured with both portable and buried TDR probes, varied between 0.24 and 0.58, depending on the site considered. In order to reduce the effect of small-scale variability, a spatial smoothing filter was applied which allowed the estimation of linear relationships with higher coefficient of correlation (r ∼ 0.46-0.8). The accuracy obtained in the estimation of the temporal trend of the soil moisture spatial averages was in the range ∼4.5-7.8% v/v and up to the ∼70% of the point soil moisture variance was explained by the ECa signal. The obtained results highlighted the potential of EMI to provide, in a short time, sufficiently accurate estimate of soil moisture over large areas that are highly needed for hydrological and remote sensing applications.

  15. Multi-frequency weak signal detection based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance

    NASA Astrophysics Data System (ADS)

    Han, Dongying; li, Pei; An, Shujun; Shi, Peiming

    2016-03-01

    In actual fault diagnosis, useful information is often submerged in heavy noise, and the feature information is difficult to extract. A novel weak signal detection method aimed at the problem of detecting multi-frequency signals buried under heavy background noise is proposed based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance (SR). First, the noisy signal is processed by parameter compensation, with the noise and system parameters expanded 10 times to counteract the effect of the damping term. The processed signal is decomposed into multiple signals of different scale frequencies by wavelet transform. Following this, we adjust the size of the scaled signals' amplitudes and reconstruct the signals; the weak signal frequency components are then enhanced by multi-stable stochastic resonance. The enhanced components of the signal are processed through a band-pass filter, leaving the enhanced sections of the signal. The processed signal is analyzed by FFT to achieve detection of the multi-frequency weak signals. The simulation and experimental results show that the proposed method can enhance the signal amplitude, can effectively detect multi-frequency weak signals buried under heavy noise and is valuable and usable for bearing fault signal analysis.

  16. Multi-frequency study of the newly confirmed supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kavanagh, P. J.; Sasaki, M.; Bozzetto, L. M.; Points, S. D.; Filipović, M. D.; Maggi, P.; Haberl, F.; Crawford, E. J.

    2015-11-01

    Aims: We present a multi-frequency study of the supernova remnant MCSNR J0512-6707 in the Large Magellanic Cloud. Methods: We used new data from XMM-Newton to characterise the X-ray emission and data from the Australian Telescope Compact Array, the Magellanic Cloud Emission Line Survey, and Spitzer to gain a picture of the environment into which the remnant is expanding. We performed a morphological study, determined radio polarisation and magnetic field orientation, and performed an X-ray spectral analysis. Results: We estimated the remnant's size to be 24.9 ( ± 1.5) × 21.9 ( ± 1.5) pc, with the major axis rotated ~29° east of north. Radio polarisation images at 3 cm and 6 cm indicate a higher degree of polarisation in the northwest and southeast tangentially oriented to the SNR shock front, indicative of an SNR compressing the magnetic field threading the interstellar medium. The X-ray spectrum is unusual as it requires a soft (~0.2 keV) collisional ionisation equilibrium thermal plasma of interstellar medium abundance, in addition to a harder component. Using our fit results and the Sedov dynamical model, we showed that the thermal emission is not consistent with a Sedov remnant. We suggested that the thermal X-rays can be explained by MCSNR J0512-6707 having initially evolved into a wind-blown cavity and is now interacting with the surrounding dense shell. The origin of the hard component remains unclear. We could not determine the supernova type from the X-ray spectrum. Indirect evidence for the type is found in the study of the local stellar population and star formation history in the literature, which suggests a core-collapse origin. Conclusions: MCSNR J0512-6707 likely resulted from the core-collapse of high mass progenitor which carved a low density cavity into its surrounding medium, with the soft X-rays resulting from the impact of the blast wave with the surrounding shell. The unusual hard X-ray component requires deeper and higher spatial

  17. Design of smoothed multi-flared antenna for multi-frequency reception of direct transmission from meteorological satellites

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kesarkar, Amit P.; Thawait, Prateek

    2016-07-01

    The direct radiance data assimilation is found to be advantageous for the numerical weather prediction over short and medium range. Therefore reception of satellite radiance in real time is important. Satellite earth station is the preferred choice for direct reception of this data, which is voluminous. High Rate Information being transmitted from these satellites operating in L, S, C and X bands needs to be received. A commercial wide band antenna is not preferred for such application, as it operates uniformly over the entire frequency range in these bands and may create interference over the unwanted frequencies. As the frequencies of interest occupy only a small portion of these bands, it is essential to design a horn antenna, which receives only specified frequencies and filter other frequencies. In this work, we have designed a multi-flare multi-frequency cylindrical horn antenna for reception of direct transmission from meteorological satellites. This earth station antenna tracks selected satellites working over specified frequency ranges, which are 1.694-1.703 GHz, 2.0-2.06 GHz, 4.5-4.6 GHz and 7.8-7.9 GHz in L, S, C and X bands respectively. Cylindrical waveguides for the frequencies, 1.6, 2, 4.5 and 8 GHz are designed and they are joined in the increasing order of radius with suitable conical shapes. The slope of the cones is adjusted experimentally. With this design, the return loss is simulated and found to be better than 20 dB upto 4.5 GHz and later it became poor. To overcome this difficulty, the abrupt transitions at the joints of the conical and cylindrical waveguides are made smoothen by increasing the diameter of one mouth of the cylinder and reducing the other mouth to match with the cylinders corresponding to next higher and lower frequency respectively. As a result, a smooth flared antenna is obtained and the simulated results are satisfactory. A parabolic reflector of 4 m diameter is designed and the smooth multi-flared antenna is kept at the

  18. MAGIC gamma-ray and multi-frequency observations of flat spectrum radio quasar PKS 1510-089 in early 2012

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Delgado Mendez, C.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadasch, D.; Hayashida, M.; Herrera, J.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Kellermann, H.; Kodani, K.; Konno, Y.; Krause, J.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nishijima, K.; Noda, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Partini, S.; Persic, M.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Preziuso, S.; Puljak, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Rügamer, S.; Saggion, A.; Saito, T.; Saito, K.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamatescu, V.; Stamerra, A.; Steinbring, T.; Storz, J.; Strzys, M.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Zandanel, F.; Zanin, R.; MAGIC Collaboration; Lucarelli, F.; Pittori, C.; Vercellone, S.; Verrecchia, F.; AGILE Collaboration; Buson, S.; D'Ammando, F.; Stawarz, L.; Giroletti, M.; Orienti, M.; Fermi-LAT Collaboration; Mundell, C.; Steele, I.; Zarpudin, B.; Raiteri, C. M.; Villata, M.; Sandrinelli, A.; Lähteenmäki, A.; Tammi, J.; Tornikoski, M.; Hovatta, T.; Readhead, A. C. S.; Max-Moerbeck, W.; Richards, J. L.; Jorstad, S.; Marscher, A.; Gurwell, M. A.; Larionov, V. M.; Blinov, D. A.; Konstantinova, T. S.; Kopatskaya, E. N.; Larionova, L. V.; Larionova, E. G.; Morozova, D. A.; Troitsky, I. S.; Mokrushina, A. A.; Pavlova, Yu. V.; Chen, W. P.; Lin, H. C.; Panwar, N.; Agudo, I.; Casadio, C.; Gómez, J. L.; Molina, S. N.; Kurtanidze, O. M.; Nikolashvili, M. G.; Kurtanidze, S. O.; Chigladze, R. A.; Acosta-Pulido, J. A.; Carnerero, M. I.; Manilla-Robles, A.; Ovcharov, E.; Bozhilov, V.; Metodieva, I.; Aller, M. F.; Aller, H. D.; Fuhrman, L.; Angelakis, E.; Nestoras, I.; Krichbaum, T. P.; Zensus, J. A.; Ungerechts, H.; Sievers, A.

    2014-09-01

    Aims: Amongst more than fifty blazars detected in very high energy (VHE, E> 100 GeV) γ rays, only three belong to the subclass of flat spectrum radio quasars (FSRQs). The detection of FSRQs in the VHE range is challenging, mainly because of their soft spectra in the GeV-TeV regime. MAGIC observed PKS 1510-089 (z = 0.36) starting 2012 February 3 until April 3 during a high activity state in the high energy (HE, E> 100 MeV) γ-ray band observed by AGILE and Fermi. MAGIC observations result in the detection of a source with significance of 6.0 standard deviations (σ). We study the multi-frequency behaviour of the source at the epoch of MAGIC observation, collecting quasi-simultaneous data at radio and optical (GASP-WEBT and F-Gamma collaborations, REM, Steward, Perkins, Liverpool, OVRO, and VLBA telescopes), X-ray (Swift satellite), and HE γ-ray frequencies. Methods: We study the VHE γ-ray emission, together with the multi-frequency light curves, 43 GHz radio maps, and spectral energy distribution (SED) of the source. The quasi-simultaneous multi-frequency SED from the millimetre radio band to VHE γ rays is modelled with a one-zone inverse Compton model. We study two different origins of the seed photons for the inverse Compton scattering, namely the infrared torus and a slow sheath surrounding the jet around the Very Long Baseline Array (VLBA) core. Results: We find that the VHE γ-ray emission detected from PKS 1510-089 in 2012 February-April agrees with the previous VHE observations of the source from 2009 March-April. We find no statistically significant variability during the MAGIC observations on daily, weekly, or monthly time scales, while the other two known VHE FSRQs (3C 279 and PKS 1222+216) have shown daily scale to sub-hour variability. The γ-ray SED combining AGILE, Fermi and MAGIC data joins smoothly and shows no hint of a break. The multi-frequency light curves suggest a common origin for the millimetre radio and HE γ-ray emission, and the HE

  19. A Multi-frequency analysis of dark matter annihilation interpretations of recent anti-particle and γ-ray excesses in cosmic structures

    NASA Astrophysics Data System (ADS)

    Beck, G.; Colafrancesco, S.

    2016-05-01

    The Fermi-LAT observation of a γ-ray excess from the galactic-centre, as well as the PAMELA, AMS, and AMS-2 anti-particle excesses, and the recent indications of a Fermi-LAT γ-ray excess in the Reticulum II dwarf galaxy have all been variously put forward as possible indirect signatures of supersymmetric neutralino dark matter. These are of particular interest as the neutralino annihilation models which fit these observations must have observable consequences across the frequency spectrum, from radio to γ-ray emission. Moreover, since dark matter is expected to be a major constituent of cosmic structure, these multi-frequency consequences should be common to such structures across the mass spectrum, from dwarf galaxies to galaxy clusters. Thus, in this work we make predictions for the multi-frequency spectra of three well-known sources dominated by dark matter on cluster, galaxy and dwarf galaxy scales, e.g. the Coma cluster, the galaxy M81, and the Draco dwarf galaxy, using models favoured by dark matter interpretations of the aforementioned observations. We pay special attention to the consequences for these models when their cross-sections are renormalised to reproduce the recent γ-ray excess observed in the Reticulum II dwarf galaxy, as well as using cross-sections from the Fermi-LAT dwarf galaxy limits, which throw a dark matter interpretation of this excess into doubt. We find that the multi-frequency data of Coma and Draco are in conflict with the dark matter interpretation of the AMS, PAMELA and Fermi positron excess. Additionally, models derived from Fermi-LAT galactic centre observations, and AMS-2 re-analysis, present similar but less extensive conflicts. Using the sensitivity projections for the Square Kilometre Array, the Cherenkov Telescope Array, as well as the ASTROGAM and ASTRO-H satellites, we determine the detection prospects for a subset of neutralino models that remain consistent with Planck cosmological constraints. Although the SKA has

  20. Detecting new γ-ray sources based on multi-frequency data the case of 1WHSPJ031423.9+061956

    NASA Astrophysics Data System (ADS)

    Arsioli, Bruno; Chang, Yu Ling

    2015-12-01

    We use the Fermi Science Tools in an attempt to unveil faint γ-ray blazars that may be above the threshold for detectability with Fermi-LAT and are not identified by automated methods. Our search for new sources in the 100MeV-300GeV band is mainly driven by the 1/2WHSP catalogs, which list high synchrotron peaked blazars expected to be emitters of VHE photons. Here we present the γ-ray detection of 1WHSP J031423.9+061956, modelling its high energy spectrum as a power law. We describe an example where multi-frequency selection, performed at much lower energies (from radio to X-ray), helps to pin-point a high energy source. The 1/2WHSP catalogs are built with the aim of providing a list of TeV targets for the VHE arrays of Cherenkov telescopes. Moreover, these catalogs provide useful seeds for identifying new high energy sources within the raw-data from Fermi. With the aid of multi-frequency data, we can explore the very high energy domain in greater details, improving the description of the γ-ray sky.

  1. Detecting new γ-ray sources based on multi-frequency data the case of 1WHSPJ031423.9+061956

    SciTech Connect

    Arsioli, Bruno; Chang, Yu Ling

    2015-12-17

    We use the Fermi Science Tools in an attempt to unveil faint γ-ray blazars that may be above the threshold for detectability with Fermi-LAT and are not identified by automated methods. Our search for new sources in the 100MeV-300GeV band is mainly driven by the 1/2WHSP catalogs, which list high synchrotron peaked blazars expected to be emitters of VHE photons. Here we present the γ-ray detection of 1WHSP J031423.9+061956, modelling its high energy spectrum as a power law. We describe an example where multi-frequency selection, performed at much lower energies (from radio to X-ray), helps to pin-point a high energy source. The 1/2WHSP catalogs are built with the aim of providing a list of TeV targets for the VHE arrays of Cherenkov telescopes. Moreover, these catalogs provide useful seeds for identifying new high energy sources within the raw-data from Fermi. With the aid of multi-frequency data, we can explore the very high energy domain in greater details, improving the description of the γ-ray sky.

  2. Zooplankton and micronekton biovolume at the Mid-Atlantic Ridge and Charlie-Gibbs Fracture Zone estimated by multi-frequency acoustic survey

    NASA Astrophysics Data System (ADS)

    Cox, Martin J.; Letessier, Tom B.; Brierley, Andrew S.

    2013-12-01

    To examine the potential influence of the Mid-Atlantic Ridge and Charlie-Gibbs Fracture Zone on zooplankton and micronekton biovolume in the upper 200 m of the water column, multi-frequency acoustic data (18, 38, 70, 120 and 200 kHz) were acquired at four study sites from the RRS James Cook using hull-mounted scientific echosounders. Multi-frequency inversion techniques were employed to classify each 20 m depth×500 m along-track region of the water column to a zooplankton or micronekton acoustic scatterering class, such as copepod or euphausiid, and to estimate biovolume. We found a highly significant north-south (across fracture zone) difference in areal biovolume (p-value=0.01) but no significant east-west (across ridge) difference (p-value=0.07). Areal biovolume at all sites was dominated by the acoustic scatter class ‘euphausiid’, with higher biovolumes occurring in the southern stations. Our acoustic observations suggest the existence of different pelagic communities to the north and south of the SPF, with the southern community having a greater proportion of fish.

  3. ENCODE data at the ENCODE portal.

    PubMed

    Sloan, Cricket A; Chan, Esther T; Davidson, Jean M; Malladi, Venkat S; Strattan, J Seth; Hitz, Benjamin C; Gabdank, Idan; Narayanan, Aditi K; Ho, Marcus; Lee, Brian T; Rowe, Laurence D; Dreszer, Timothy R; Roe, Greg; Podduturi, Nikhil R; Tanaka, Forrest; Hong, Eurie L; Cherry, J Michael

    2016-01-01

    The Encyclopedia of DNA Elements (ENCODE) Project is in its third phase of creating a comprehensive catalog of functional elements in the human genome. This phase of the project includes an expansion of assays that measure diverse RNA populations, identify proteins that interact with RNA and DNA, probe regions of DNA hypersensitivity, and measure levels of DNA methylation in a wide range of cell and tissue types to identify putative regulatory elements. To date, results for almost 5000 experiments have been released for use by the scientific community. These data are available for searching, visualization and download at the new ENCODE Portal (www.encodeproject.org). The revamped ENCODE Portal provides new ways to browse and search the ENCODE data based on the metadata that describe the assays as well as summaries of the assays that focus on data provenance. In addition, it is a flexible platform that allows integration of genomic data from multiple projects. The portal experience was designed to improve access to ENCODE data by relying on metadata that allow reusability and reproducibility of the experiments. PMID:26527727

  4. ENCODE data at the ENCODE portal

    PubMed Central

    Sloan, Cricket A.; Chan, Esther T.; Davidson, Jean M.; Malladi, Venkat S.; Strattan, J. Seth; Hitz, Benjamin C.; Gabdank, Idan; Narayanan, Aditi K.; Ho, Marcus; Lee, Brian T.; Rowe, Laurence D.; Dreszer, Timothy R.; Roe, Greg; Podduturi, Nikhil R.; Tanaka, Forrest; Hong, Eurie L.; Cherry, J. Michael

    2016-01-01

    The Encyclopedia of DNA Elements (ENCODE) Project is in its third phase of creating a comprehensive catalog of functional elements in the human genome. This phase of the project includes an expansion of assays that measure diverse RNA populations, identify proteins that interact with RNA and DNA, probe regions of DNA hypersensitivity, and measure levels of DNA methylation in a wide range of cell and tissue types to identify putative regulatory elements. To date, results for almost 5000 experiments have been released for use by the scientific community. These data are available for searching, visualization and download at the new ENCODE Portal (www.encodeproject.org). The revamped ENCODE Portal provides new ways to browse and search the ENCODE data based on the metadata that describe the assays as well as summaries of the assays that focus on data provenance. In addition, it is a flexible platform that allows integration of genomic data from multiple projects. The portal experience was designed to improve access to ENCODE data by relying on metadata that allow reusability and reproducibility of the experiments. PMID:26527727

  5. Multi-frequency subspace migration for imaging of perfectly conducting, arc-like cracks in full- and limited-view inverse scattering problems

    NASA Astrophysics Data System (ADS)

    Park, Won-Kwang

    2015-02-01

    Multi-frequency subspace migration imaging techniques are usually adopted for the non-iterative imaging of unknown electromagnetic targets, such as cracks in concrete walls or bridges and anti-personnel mines in the ground, in the inverse scattering problems. It is confirmed that this technique is very fast, effective, robust, and can not only be applied to full- but also to limited-view inverse problems if a suitable number of incidents and corresponding scattered fields are applied and collected. However, in many works, the application of such techniques is heuristic. With the motivation of such heuristic application, this study analyzes the structure of the imaging functional employed in the subspace migration imaging technique in two-dimensional full- and limited-view inverse scattering problems when the unknown targets are arbitrary-shaped, arc-like perfectly conducting cracks located in the two-dimensional homogeneous space. In contrast to the statistical approach based on statistical hypothesis testing, our approach is based on the fact that the subspace migration imaging functional can be expressed by a linear combination of the Bessel functions of integer order of the first kind. This is based on the structure of the Multi-Static Response (MSR) matrix collected in the far-field at nonzero frequency in either Transverse Magnetic (TM) mode (Dirichlet boundary condition) or Transverse Electric (TE) mode (Neumann boundary condition). The investigation of the expression of imaging functionals gives us certain properties of subspace migration and explains why multi-frequency enhances imaging resolution. In particular, we carefully analyze the subspace migration and confirm some properties of imaging when a small number of incident fields are applied. Consequently, we introduce a weighted multi-frequency imaging functional and confirm that it is an improved version of subspace migration in TM mode. Various results of numerical simulations performed on the far

  6. Multi-frequency inversion-charge pumping for charge separation and mobility analysis in high-k/InGaAs metal-oxide-semiconductor field-effect transistors

    SciTech Connect

    Djara, V.; Cherkaoui, K.; Negara, M. A.; Hurley, P. K.

    2015-11-28

    An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (N{sub inv}) from the trapped charge density in high-k/InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed I{sub d}-V{sub g} measurements enabled an accurate effective mobility vs N{sub inv} extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs.

  7. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

    NASA Astrophysics Data System (ADS)

    Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.

    2015-12-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.

  8. Alignment system for encoders

    NASA Technical Reports Server (NTRS)

    Villani, Daniel D. (Inventor)

    1988-01-01

    An improved encoder alignment system is disclosed which provides an indication of the extent of misalignment and a measure of the rate at which the misalignment may be changing. The invention is adapted for use with a conventional encoder which provides a digital coarse word having at least significant bit and a digital fine word having a least significant bit and a most significant bit. The invention generates the exclusive or of the least significant bit of the coarse digital signal and the least significant bit of the fine digital signal to provide a first signal. The invention then generates the exclusive or of the first signal and the complement of the most significant bit of the fine digital signal to provide an output signal which represents the misalignment of the encoder.

  9. Analysis of post-sunset F-region vertical plasma drifts during Counter Electrojet days using multi frequency HF Doppler Radar

    NASA Astrophysics Data System (ADS)

    Simi, K. G.; Vineeth, C.; Pant, T. K.

    2014-08-01

    In this paper, through a case study, an attempt has been made to bring out the relationship between post noon E-region electric field and post sunset F-region vertical plasma drift on quiet time Counter Electrojet (CEJ) days. Study carried out using the data from a multi frequency HF Doppler Radar and Digital Ionosonde located over Trivandrum (8.5° N; 77° E; 0.5° N dip lat.) a geomagnetic dip equatorial station in India during quite time CEJ days of the years 2004 and 2006, revealed some interesting aspects of the E region electrodynamics and post sunset F region electrodynamics. It has been observed that, in contrast to the normal electrojet (EEJ) days, the Pre-Reversal Enhancement (PRE) is either weakened or inhibited on CEJ days and the field reversal takes place much earlier than that on a normal day. It is suggested that even after the effects of the field reversal ceases to show up in the ground magnetic data, the reversed field may persist and shows up as a decrease in the PRE experienced by the F-region. In other words, the study indicates that the EEJ associated electrodynamics have a significant role in controlling the PRE.

  10. Fusion of space-borne multi-baseline and multi-frequency interferometric results based on extended Kalman filter to generate high quality DEMs

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaojie; Zeng, Qiming; Jiao, Jian; Zhang, Jingfa

    2016-01-01

    Repeat-pass Interferometric Synthetic Aperture Radar (InSAR) is a technique that can be used to generate DEMs. But the accuracy of InSAR is greatly limited by geometrical distortions, atmospheric effect, and decorrelations, particularly in mountainous areas, such as western China where no high quality DEM has so far been accomplished. Since each of InSAR DEMs generated using data of different frequencies and baselines has their own advantages and disadvantages, it is therefore very potential to overcome some of the limitations of InSAR by fusing Multi-baseline and Multi-frequency Interferometric Results (MMIRs). This paper proposed a fusion method based on Extended Kalman Filter (EKF), which takes the InSAR-derived DEMs as states in prediction step and the flattened interferograms as observations in control step to generate the final fused DEM. Before the fusion, detection of layover and shadow regions, low-coherence regions and regions with large height error is carried out because MMIRs in these regions are believed to be unreliable and thereafter are excluded. The whole processing flow is tested with TerraSAR-X and Envisat ASAR datasets. Finally, the fused DEM is validated with ASTER GDEM and national standard DEM of China. The results demonstrate that the proposed method is effective even in low coherence areas.

  11. Multi-frequency investigation of the parsec- and kilo-parsec-scale radio structures in high-redshift quasar PKS ;1402+044

    NASA Astrophysics Data System (ADS)

    Yang, J.; Gurvits, L. I.; Lobanov, A. P.; Frey, S.; Hong, X.-Y.

    2008-10-01

    Aims: We investigate the frequency-dependent radio properties of the jet of the luminous high-redshift (z=3.2) radio quasar PKS 1402+044 (J1405+0415) by means of radio interferometric observations. Methods: The observational data were obtained with the VLBI Space Observatory Programme (VSOP) at 1.6 and 5 GHz, supplemented by other multi-frequency observations with the Very Long Baseline Array (VLBA; 2.3, 8.4, and 15 GHz) and the Very Large Array (VLA; 1.4, 5, 15, and 43 GHz). The observations span a period of 7 years. Results: We find that the luminous high-redshift quasar PKS 1402+044 has a pronounced “core-jet” morphology from the parsec to the kilo-parsec scales. The jet shows a steeper spectral index and lower brightness temperature with increasing distance from the jet core. The variation of brightness temperature agrees well with the shock-in-jet model. Assuming that the jet is collimated by the ambient magnetic field, we estimate the mass of the central object as ~10^9~M_⊙. The upper limit of the jet proper motion of PKS 1402+044 is 0.03 mas yr-1 (~3c) in the east-west direction.

  12. A high-frequency electron paramagnetic resonance spectrometer for multi-dimensional, multi-frequency, and multi-phase pulsed measurements

    SciTech Connect

    Cho, F. H.; Stepanov, V.; Takahashi, S.

    2014-07-15

    We describe instrumentation for a high-frequency electron paramagnetic resonance (EPR) and pulsed electron-electron double resonance (PELDOR) spectroscopy. The instrumentation is operated in the frequency range of 107−120 GHz and 215−240 GHz and in the magnetic field range of 0−12.1 T. The spectrometer consisting of a high-frequency high-power solid-state source, a quasioptical system, a phase-sensitive detection system, a cryogenic-free superconducting magnet, and a {sup 4}He cryostat enables multi-frequency continuous-wave EPR spectroscopy as well as pulsed EPR measurements with a few hundred nanosecond pulses. Here we discuss the details of the design and the pulsed EPR sensitivity of the instrumentation. We also present performance of the instrumentation in unique experiments including PELDOR spectroscopy to probe correlations in an insulating electronic spin system and application of dynamical decoupling techniques to extend spin coherence of electron spins in an insulating solid-state system.

  13. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study.

    PubMed

    Villa, Federica; Magnani, Alessandro; Maggioni, Martina A; Stahn, Alexander; Rampichini, Susanna; Merati, Giampiero; Castiglioni, Paolo

    2016-01-01

    Bioelectrical Impedance Spectroscopy (BIS) allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously. PMID:27187389

  14. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

    PubMed Central

    Villa, Federica; Magnani, Alessandro; Maggioni, Martina A.; Stahn, Alexander; Rampichini, Susanna; Merati, Giampiero; Castiglioni, Paolo

    2016-01-01

    Bioelectrical Impedance Spectroscopy (BIS) allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously. PMID:27187389

  15. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

    PubMed

    Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

    2016-01-01

    In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor. PMID:27472331

  16. Polarization encoded color camera.

    PubMed

    Schonbrun, Ethan; Möller, Guðfríður; Di Caprio, Giuseppe

    2014-03-15

    Digital cameras would be colorblind if they did not have pixelated color filters integrated into their image sensors. Integration of conventional fixed filters, however, comes at the expense of an inability to modify the camera's spectral properties. Instead, we demonstrate a micropolarizer-based camera that can reconfigure its spectral response. Color is encoded into a linear polarization state by a chiral dispersive element and then read out in a single exposure. The polarization encoded color camera is capable of capturing three-color images at wavelengths spanning the visible to the near infrared. PMID:24690806

  17. Video Time Encoding Machines

    PubMed Central

    Lazar, Aurel A.; Pnevmatikakis, Eftychios A.

    2013-01-01

    We investigate architectures for time encoding and time decoding of visual stimuli such as natural and synthetic video streams (movies, animation). The architecture for time encoding is akin to models of the early visual system. It consists of a bank of filters in cascade with single-input multi-output neural circuits. Neuron firing is based on either a threshold-and-fire or an integrate-and-fire spiking mechanism with feedback. We show that analog information is represented by the neural circuits as projections on a set of band-limited functions determined by the spike sequence. Under Nyquist-type and frame conditions, the encoded signal can be recovered from these projections with arbitrary precision. For the video time encoding machine architecture, we demonstrate that band-limited video streams of finite energy can be faithfully recovered from the spike trains and provide a stable algorithm for perfect recovery. The key condition for recovery calls for the number of neurons in the population to be above a threshold value. PMID:21296708

  18. Time-Encoded Imagers.

    SciTech Connect

    Marleau, Peter; Brubaker, Erik

    2014-11-01

    This report provides a short overview of the DNN R&D funded project, Time-Encoded Imagers. The project began in FY11 and concluded in FY14. The Project Description below provides the overall motivation and objectives for the project as well as a summary of programmatic direction. It is followed by a short description of each task and the resulting deliverables.

  19. Reed-Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Troung, T. K.; Reed, I. S.; Deutsch, L. J.; Hsu, I. S.; Wang, K.; Yeh, C. S.

    1985-01-01

    Report presents mathematical principles of Berlekamp bit serial multiplier algorithm and its application to design of very-large-scale integrated (VLSI) encoders for Reed-Solomon error-correcting codes. Structure made readily on single chip of negatively doped channel metal oxide semiconductor.

  20. Plasmids encoding therapeutic agents

    DOEpatents

    Keener, William K.

    2007-08-07

    Plasmids encoding anti-HIV and anti-anthrax therapeutic agents are disclosed. Plasmid pWKK-500 encodes a fusion protein containing DP178 as a targeting moiety, the ricin A chain, an HIV protease cleavable linker, and a truncated ricin B chain. N-terminal extensions of the fusion protein include the maltose binding protein and a Factor Xa protease site. C-terminal extensions include a hydrophobic linker, an L domain motif peptide, a KDEL ER retention signal, another Factor Xa protease site, an out-of-frame buforin II coding sequence, the lacZ.alpha. peptide, and a polyhistidine tag. More than twenty derivatives of plasmid pWKK-500 are described. Plasmids pWKK-700 and pWKK-800 are similar to pWKK-500 wherein the DP178-encoding sequence is substituted by RANTES- and SDF-1-encoding sequences, respectively. Plasmid pWKK-900 is similar to pWKK-500 wherein the HIV protease cleavable linker is substituted by a lethal factor (LF) peptide-cleavable linker.

  1. Agreement of single- and multi-frequency Bioimpedance Measurements in hemodialysis patients: An Ancillary Study of the Frequent Hemodialysis Network (FHN) Daily Trial

    PubMed Central

    Raimann, Jochen G.; Abbas, Samer R.; Liu, Li; Zhu, Fansan; Larive, Brett; Kotanko, Peter; Levin, Nathan W.; Kaysen, George A.

    2015-01-01

    Background Bioimpedance analysis (BIA) is well established to assess body composition. Agreements between single- and multi-frequency bioimpedance (SF-BIA, MF-BIS) assessments in subjects undergoing 6 or 3 times per week hemodialysis (HD) were analyzed. Methods Total body water (TBW), intra- and extracellular fluid (ICF, ECF) of subjects enrolled in the Frequent Hemodialysis Network (FHN) Daily Trial (www.clinicaltrials.gov # NCT00264758) were measured with a Hydra 4200 at baseline (BL) and at 5 months (M5). Volumes were computed using SF (at 50 kHz) and MF approaches. Agreement was assessed by means of Linear Regression and Bland-Altman analysis and treatment effects by T-Test. Results 35 subjects (17 on the more frequent regimen, 26 male, 20 blacks, 48±9 years, pre-HD weight 84±19 kg) were studied. Assessments with SF-BIA and MF-BIS correlated significantly at BL and M5 in both arms. No proportional errors, but systematic biases over the entire range of values were found at BL and M5. Agreement did not differ between subjects randomized to either HD treatment arm at both time points. MF-BIS appears to have better precision than SF-BIA allowing the observation of a significant treatment effect by the intervention [−1.5 (95% CI −2.5 to −0.5) L] on ECF, not found for ECF SF-BIA. Precision also affected the statistical power of the SF-BIA data in the current analysis. Conclusion Both methods showed agreement without significant proportional errors regardless of HD frequency and can be used for longitudinal analyses. SF-BIA has lower precision which needs thorough consideration in the design of future trials with similar outcomes. PMID:25402657

  2. High-resolution observation of field-aligned irregularities in the ionosphere using multi-frequency range imaging of VHF atmospheric radar

    NASA Astrophysics Data System (ADS)

    Chen, Jenn-Shyong; Furumoto, Jun-ichi; Su, Ching-Lun; Chu, Yen-Hsyang

    Field-aligned irregularity (FAI) in the ionosphere is a topic of interest to atmospheric radar community. In addition to the field-aligned characteristic, quasi-periodic (QP) appearance of FAI echoes has been observed frequently by very-high-frequency (VHF) atmospheric radar. The occurrence range of QP FAI echoes changes with time, and the slope of range versus time can be positive or negative, depending on occurrence time of the echoes. Several mechanisms responsible for the QP FAI echoes have been proposed, e.g., modulation in altitude by a passing atmospheric gravity wave, semidiurnal neutral-wind variation, and so on. Owing to the finite pulse length of radar in observation, the range resolution of measurement is limited within hundreds of meters. In view of this, the range imaging (RIM) using multiple frequencies has been employed to improve the range resolution of measurement. The multi-frequency technique transmits a set of slightly different frequencies sequentially during each radar pulse, and the radar returns at different transmitting frequencies are received, respectively. With adaptive retrieval algorithms for these radar returns, it is capable of resolving the echo structures at meter scale in the range direction. RIM has been employed in the lower atmosphere successfully. In this study, the performance of RIM for FAI was first carried out with the Middle and Upper atmosphere Radar (46 MHz; 34.85(°) N, 136.10(°) N; Japan) and the Chung-Li VHF radar (52 MHz; 24.9(°) N, 121.1(°) E; Taiwan). Some initial results of high-resolution FAI echoes within the range gate will be shown.

  3. Comparison of multi-frequency bioimpedance with perometry for the early detection and intervention of lymphoedema after axillary node clearance for breast cancer.

    PubMed

    Bundred, Nigel J; Stockton, Charlotte; Keeley, Vaughan; Riches, Katie; Ashcroft, Linda; Evans, Abigail; Skene, Anthony; Purushotham, Arnie; Bramley, Maria; Hodgkiss, Tracey

    2015-05-01

    The importance of early detection of lymphoedema by arm volume measurements before surgery and repeated measurements after surgery in women undergoing axillary node clearance (ANC) in order to enable early intervention is recognised. A prospective multi-centre study was performed which studied the difference between multi-frequency bioimpedance electrical analysis (BIS) and perometer arm measurement in predicting the development of lymphoedema. Women undergoing ANC underwent pre-operative and regular post-operative measurements of arm volume by both methods. The primary endpoint is the incidence of lymphoedema (≥10 % arm volume increase compared to contralateral arm by perometer) at 2 and 5 years after ANC. The threshold for intervention in lymphoedema was also assessed. Out of 964 patients recruited, 612 had minimum 6 months follow-up data. Using 1-month post-operative measurements as baseline, perometer detected 31 patients with lymphoedema by 6 months (BIS detected 53). By 6 months, 89 % of those with no lymphoedema reported at least one symptom. There was moderate correlation between perometer and BIS at 3 months (r = 0.40) and 6 months (r = 0.60), with a sensitivity of 73 % and specificity of 84 %. Univariate and multivariate analyses revealed a threshold for early intervention of ≥5 to <10 % (p = 0.03). Threshold for early intervention to prevent progression to lymphoedema is ≥5 to <10 % but symptoms alone do not predict lymphoedema. The modest correlation between methods at 6 months indicates arm volume measurements remain gold standard, although longer term follow-up is required. PMID:25850535

  4. The Text Encoding Initiative: Flexible and Extensible Document Encoding.

    ERIC Educational Resources Information Center

    Barnard, David T.; Ide, Nancy M.

    1997-01-01

    The Text Encoding Initiative (TEI), an international collaboration aimed at producing a common encoding scheme for complex texts, examines the requirement for generality versus the requirement to handle specialized text types. Discusses how documents and users tax the limits of fixed schemes requiring flexible extensible encoding to support…

  5. VLSI Reed-Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Liu, K. Y.

    1983-01-01

    Modular Reed-solomon encoder uses identical custom VLSI chips called "symbol slices." By cascading and properly interconnecting group of these chips, encoder is made for any desired error-correcting capability and interleaving level. VLSI encoder requires only one-tenth the number of chips required by conventional Reed-Solomon Circuit implemented with discrete IC's.

  6. Slow and fast narrow spectra aurora E region echoes during the March 17, 2015 storm at mid latitudes. Multi-static, multi-frequency radar observations

    NASA Astrophysics Data System (ADS)

    Chau, Jorge; St-Maurice, Jean-Pierre

    2016-07-01

    Coherent E region echoes were observed at midlatitudes during the March 17, 2015 storm. The observations came from multi-static, multi-frequency, wide-field of view radars operating at 32.55 and 36.2 MHz in northern Germany. Each of the three receiver stations used, two in monostatic and one in bistatic modes, allow interferometry. These radars systems are devoted primarily to the measurement of mesospheric winds from specular meteor echoes. However during this storm, the strongest of the current solar cycle, strong Radar Aurora echoes were observed during the day for more than four hours. Here we present the main features observed, with a specific emphasis on echoes presenting narrow spectra with slower (around 180 m/s) and faster (as fast as 1600 m/s) Doppler velocities, than nominal typical ion-acoustic velocity expected to be between 400 and 800 m/s. We find that in both types of echoes the range vs. time slopes are between 800 and 1400 m/s. They agree rather well with the Doppler velocity for the narrow fast types but do not agree at all in the narrow slow spectral case. In both instances, the echoes are organized in localized horizontal structures with a range extent typically between 50 and 80 km. The fast-narrow structures tend to occur at higher altitudes than the well-known Farley-Buneman echoes, while the slow-narrow structures occur at lower altitudes (lower than 95 km). Both echo types come from regions with relatively small flow angles. Moreover the altitude of all echoes went down after 16:15 UT with the small-narrow echoes acquiring even smaller Doppler velocities. In large part thanks to the echo localization made feasible by interferometry, these new features are shedding some new important perspective on our understanding of auroral E-region radar echoes, particularly when it comes to spectra classified in the past as "Type III" and "Type IV" echoes.

  7. Time encoded radiation imaging

    DOEpatents

    Marleau, Peter; Brubaker, Erik; Kiff, Scott

    2014-10-21

    The various technologies presented herein relate to detecting nuclear material at a large stand-off distance. An imaging system is presented which can detect nuclear material by utilizing time encoded imaging relating to maximum and minimum radiation particle counts rates. The imaging system is integrated with a data acquisition system that can utilize variations in photon pulse shape to discriminate between neutron and gamma-ray interactions. Modulation in the detected neutron count rates as a function of the angular orientation of the detector due to attenuation of neighboring detectors is utilized to reconstruct the neutron source distribution over 360 degrees around the imaging system. Neutrons (e.g., fast neutrons) and/or gamma-rays are incident upon scintillation material in the imager, the photons generated by the scintillation material are converted to electrical energy from which the respective neutrons/gamma rays can be determined and, accordingly, a direction to, and the location of, a radiation source identified.

  8. Rotary encoding device

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    1993-01-01

    A device for position encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a light beam is directed towards the facets is presented. The facets of the polygonal mirror reflect the light beam such that a light spot is created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spot on the linear array detector. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spot and to compute the position of the shaft based upon the data from the analog-to-digital converter.

  9. Linear encoding device

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    1993-01-01

    A Linear Motion Encoding device for measuring the linear motion of a moving object is disclosed in which a light source is mounted on the moving object and a position sensitive detector such as an array photodetector is mounted on a nearby stationary object. The light source emits a light beam directed towards the array photodetector such that a light spot is created on the array. An analog-to-digital converter, connected to the array photodetector is used for reading the position of the spot on the array photodetector. A microprocessor and memory is connected to the analog-to-digital converter to hold and manipulate data provided by the analog-to-digital converter on the position of the spot and to compute the linear displacement of the moving object based upon the data from the analog-to-digital converter.

  10. Field test of a multi-frequency electromagnetic induction sensor for the study of soil moisture in different land-soil units

    NASA Astrophysics Data System (ADS)

    Calamita, Giuseppe; Onorati, Beniamino; Perrone, Angela; Manfreda, Salvatore; Brocca, Luca

    2015-04-01

    appealing compared to satellite remote sensing (RS) methods. However, similarly to RS, the interpretation of the EMI measurements is not straightforward due to the simultaneous influence of different soil properties. So far, the great majority of the studies have used mono-frequency EMI sensors for periods of time shorter than one year. Moreover studies over area with medium to high vegetation density are still quite rare. The focus of this work is to evaluate the usability of the GEM-300 multi-frequency EMI sensor for spatial and temporal SM retrieval at the hillslope scale over a number of diverse land-soil units including some of the less explored types, like highland forested areas. Further, some aspects relating to the inherent stability of the GEM-300 sensor, which were never addressed before in this research area, are also explored. The test sites are located in the "Fiumarella di Corleto" experimental basin, located in Basilicata region (southern Italy). The experimentation lasted from May 2012 to May 2013. Regular grids (80 x 80 mq) and a transect (60 m) were used as spatial sampling schemes. A TDR mobile probe was used for SM measurements on the 25 points of each grid whereas fixed buried TDR probes were used on the 11 points of transect. The obtained results allowed us to investigate the spatial and temporal variability and relation between TDR and EMI sensors.

  11. Multi-frequency polarimetry of the Galactic radio background around 350 MHz. I. A region in Auriga around l = 161 deg, b = 16 deg

    NASA Astrophysics Data System (ADS)

    Haverkorn, M.; Katgert, P.; de Bruyn, A. G.

    2003-06-01

    With the Westerbork Synthesis Radio Telescope (WSRT), multi-frequency polarimetric images were taken of the diffuse radio synchrotron background in a ~ 5 deg times 7 deg region centered on (l,b) = (161 deg ,16 deg ) in the constellation of Auriga. The observations were done simultaneously in 5 frequency bands, from 341 MHz to 375 MHz, and have a resolution of ~ 5.0arcminx5 .0arcmin cosec delta . The polarized intensity P and polarization angle phi show ubiquitous structure on arcminute and degree scales, with polarized brightness temperatures up to about 13 K. On the other hand, no structure at all is observed in total intensity I to an rms limit of 1.3 K, indicating that the structure in the polarized radiation must be due to Faraday rotation and depolarization mostly in the warm component of the nearby Galactic interstellar medium (ISM). Different depolarization processes create structure in polarized intensity P. Beam depolarization creates ``depolarization canals'' of one beam wide, while depth depolarization is thought to be responsible for creating most of the structure on scales larger than a beam width. Rotation measures (RM) can be reliably determined, and are in the range -17 <~ RM <~ 10 rad m-2 with a non-zero average RM0 ~ -3.4 rad m-2. The distribution of RMs on the sky shows both abrupt changes on the scales of the beam and a gradient in the direction of positive Galactic longitude of ~ 1 rad m-2 per degree. The gradient and average RM are consistent with a regular magnetic field of ~ 1 mu G which has a pitch angle of p = -14 deg. There are 13 extragalactic sources in the field for which RMs could be derived, and those have |RM| <~ 13 rad m-2, with an estimated intrinsic source contribution of ~ 3.6 rad m-2. The RMs of the extragalactic sources show a gradient that is about 3 times larger than the gradient in the RMs of the diffuse emission and that is approximately in Galactic latitude. This difference is ascribed to a vastly different effective

  12. Space vehicle onboard command encoder

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A flexible onboard encoder system was designed for the space shuttle. The following areas were covered: (1) implementation of the encoder design into hardware to demonstrate the various encoding algorithms/code formats, (2) modulation techniques in a single hardware package to maintain comparable reliability and link integrity of the existing link systems and to integrate the various techniques into a single design using current technology. The primary function of the command encoder is to accept input commands, generated either locally onboard the space shuttle or remotely from the ground, format and encode the commands in accordance with the payload input requirements and appropriately modulate a subcarrier for transmission by the baseband RF modulator. The following information was provided: command encoder system design, brassboard hardware design, test set hardware and system packaging, and software.

  13. N-Consecutive-Phase Encoder

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Lee, Ho-Kyoung; Weber, Charles

    1995-01-01

    N-consecutive-phase encoder (NCPE) is conceptual encoder for generating alphabet of N consecutive full-response continuous-phase-modulation (CPM) signals. Enables use of binary preencoder of higher rate than used with simple continuous-phase encoder (CPE). NCPE makes possible to achieve power efficiencies and bandwidth efficiencies greater than conventional trellis coders with continuous-phase frequency-shift keying (CPFSK).

  14. Prosodic Encoding in Silent Reading.

    ERIC Educational Resources Information Center

    Wilkenfeld, Deborah

    In silent reading, short-memory tasks, such as semantic and syntactic processing, require a stage of phonetic encoding between visual representation and the actual extraction of meaning, and this encoding includes prosodic as well as segmental features. To test for this suprasegmental coding, an experiment was conducted in which subjects were…

  15. Peri-encoding predictors of memory encoding and consolidation.

    PubMed

    Cohen, Noga; Pell, Liat; Edelson, Micah G; Ben-Yakov, Aya; Pine, Alex; Dudai, Yadin

    2015-03-01

    We review reports of brain activations that occur immediately prior to the onset or following the offset of to-be-remembered information and can predict subsequent mnemonic success. Memory-predictive pre-encoding processes, occurring from fractions of a second to minutes prior to event onset, are mainly associated with activations in the medial temporal lobe (MTL), amygdala and midbrain, and with enhanced theta oscillations. These activations may be considered as the neural correlates of one or more cognitive operations, including contextual processing, attention, and the engagement of distinct computational modes associated with prior encoding or retrieval. Post-encoding activations that correlate with subsequent memory performance are mainly observed in the MTL, sensory cortices and frontal regions. These activations may reflect binding of elements of the encoded information and initiation of memory consolidation. In all, the findings reviewed here illustrate the importance of brain states in the immediate peri-encoding time windows in determining encoding success. Understanding these brain states and their specific effects on memory may lead to optimization of the encoding of desired memories and mitigation of undesired ones. PMID:25446944

  16. Information encoder/decoder using chaotic systems

    DOEpatents

    Miller, Samuel Lee; Miller, William Michael; McWhorter, Paul Jackson

    1997-01-01

    The present invention discloses a chaotic system-based information encoder and decoder that operates according to a relationship defining a chaotic system. Encoder input signals modify the dynamics of the chaotic system comprising the encoder. The modifications result in chaotic, encoder output signals that contain the encoder input signals encoded within them. The encoder output signals are then capable of secure transmissions using conventional transmission techniques. A decoder receives the encoder output signals (i.e., decoder input signals) and inverts the dynamics of the encoding system to directly reconstruct the original encoder input signals.

  17. Information encoder/decoder using chaotic systems

    DOEpatents

    Miller, S.L.; Miller, W.M.; McWhorter, P.J.

    1997-10-21

    The present invention discloses a chaotic system-based information encoder and decoder that operates according to a relationship defining a chaotic system. Encoder input signals modify the dynamics of the chaotic system comprising the encoder. The modifications result in chaotic, encoder output signals that contain the encoder input signals encoded within them. The encoder output signals are then capable of secure transmissions using conventional transmission techniques. A decoder receives the encoder output signals (i.e., decoder input signals) and inverts the dynamics of the encoding system to directly reconstruct the original encoder input signals. 32 figs.

  18. Two digital video encoder circuits

    NASA Astrophysics Data System (ADS)

    Eldon, John A.

    1992-11-01

    Central to `multimedia' image processing is the desire to encode computer graphics data into a standard television signal, complete with line, field, and color subcarrier synchronizing information. The numerous incompatibilities between television and computer display standards render this operation far less trivial than it sounds to anyone who hasn't worked with both types of signals. To simplify the task of encoding computer graphics signals into standard NTSC (North America and Japan) or PAL (most of Europe) television format for display, broadcast, or recording, TRW LSI Products Inc. has introduced the two newest members of it multimedia integrated circuit family, the TMC22090 and TMC22190 digital video encoders.

  19. Serial position encoding of signs.

    PubMed

    Miozzo, Michele; Petrova, Anna; Fischer-Baum, Simon; Peressotti, Francesca

    2016-09-01

    Reduced short-term memory (STM) capacity has been reported for sign as compared to speech when items have to be recalled in a specific order. This difference has been attributed to a more precise and efficient serial position encoding in verbal STM (used for speech) than visuo-spatial STM (used for sign). We tested in the present investigation whether the reduced STM capacity with signs stems from a lack of positional encoding available in verbal STM. Error analyses reported in prior studies have revealed that positions are defined in verbal STM by distance from both the start and the end of the sequence (both-edges positional encoding scheme). Our analyses of the errors made by deaf participants with finger-spelled letters revealed that the both-edges positional encoding scheme underlies the STM representation of signs. These results indicate that the cause of the STM disadvantage is not the type of positional encoding but rather the difficulties in binding an item in visuo-spatial STM to its specific position in the sequence. Both-edges positional encoding scheme could be specific of sign, since it has not been found in visuo-spatial STM tasks conducted with hearing participants. PMID:27244095

  20. Gravity referenced elevation encoder development

    NASA Astrophysics Data System (ADS)

    Goddard, R. E.

    1993-05-01

    Recent progress in the development of a gravity-sensor-based instrument for determining the elevation angle of DSN antennas is described. The benefits of such a system include the capability to locate the Gravity Referenced Elevation Encoder (GREE) directly on the primary reflector (thus bypassing structural flexure and deformation error sources), anticipated lower maintenance costs compared to the present gimbal encoders, direct replaceability, or supplementation of the present gimbal encoders and the utilization of off-the-shelf components to construct the GREE. This article includes a description of the nominal GREE design. Test results on a laboratory breadboard model are given. Rigid-body dynamics of the GREE are derived and the simulated performance in response to measured antenna vibrations is given.

  1. Gravity referenced elevation encoder development

    NASA Technical Reports Server (NTRS)

    Goddard, R. E.

    1993-01-01

    Recent progress in the development of a gravity-sensor-based instrument for determining the elevation angle of DSN antennas is described. The benefits of such a system include the capability to locate the Gravity Referenced Elevation Encoder (GREE) directly on the primary reflector (thus bypassing structural flexure and deformation error sources), anticipated lower maintenance costs compared to the present gimbal encoders, direct replaceability, or supplementation of the present gimbal encoders and the utilization of off-the-shelf components to construct the GREE. This article includes a description of the nominal GREE design. Test results on a laboratory breadboard model are given. Rigid-body dynamics of the GREE are derived and the simulated performance in response to measured antenna vibrations is given.

  2. Fly Photoreceptors Encode Phase Congruency.

    PubMed

    Friederich, Uwe; Billings, Stephen A; Hardie, Roger C; Juusola, Mikko; Coca, Daniel

    2016-01-01

    More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli. PMID:27336733

  3. Fly Photoreceptors Encode Phase Congruency

    PubMed Central

    Friederich, Uwe; Billings, Stephen A.; Hardie, Roger C.; Juusola, Mikko; Coca, Daniel

    2016-01-01

    More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli. PMID:27336733

  4. 47 CFR 11.32 - EAS Encoder.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false EAS Encoder. 11.32 Section 11.32 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11.32 EAS Encoder. (a) EAS Encoders must at a minimum be capable of encoding the EAS protocol described in § 11.31 and providing the EAS...

  5. 47 CFR 11.32 - EAS Encoder.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false EAS Encoder. 11.32 Section 11.32 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11.32 EAS Encoder. (a) EAS Encoders must at a minimum be capable of encoding the EAS protocol described in § 11.31 and providing the EAS...

  6. 47 CFR 11.32 - EAS Encoder.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false EAS Encoder. 11.32 Section 11.32 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL EMERGENCY ALERT SYSTEM (EAS) Equipment Requirements § 11.32 EAS Encoder. (a) EAS Encoders must at a minimum be capable of encoding the EAS protocol described in § 11.31 and providing the EAS...

  7. How Infants Encode Spatial Extent

    ERIC Educational Resources Information Center

    Duffy, Sean; Huttenlocher, Janellen; Levine, Susan; Duffy, Renee

    2005-01-01

    This study explores how infants encode an object's spatial extent. We habituated 6.5-month-old infants to a dowel inside a container and then tested whether they dishabituate to a change in absolute size when the relation between dowel and container is held constant (by altering the size of both container and dowel) and when the relation changes…

  8. Shaft encoder presents digital output

    NASA Technical Reports Server (NTRS)

    Hillis, D. A.

    1966-01-01

    Circuits that include compensation circuitry time a capacitance relative to a reference voltage so that a digital presentation occurs that is representative of the positional condition of the mechanical shaft being monitored. This circuitry may be employed in multiples to furnish binary encoding of a number of rotating devices simultaneously.

  9. Encoding Standards for Linguistic Corpora.

    ERIC Educational Resources Information Center

    Ide, Nancy

    The demand for extensive reusability of large language text collections for natural languages processing research requires development of standardized encoding formats. Such formats must be capable of representing different kinds of information across the spectrum of text types and languages, capable of representing different levels of…

  10. The PsychENCODE project

    PubMed Central

    Akbarian, Schahram; Liu, Chunyu; Knowles, James A; Vaccarino, Flora M; Farnham, Peggy J; Crawford, Gregory E; Jaffe, Andrew E; Pinto, Dalila; Dracheva, Stella; Geschwind, Daniel H; Mill, Jonathan; Nairn, Angus C; Abyzov, Alexej; Pochareddy, Sirisha; Prabhakar, Shyam; Weissman, Sherman; Sullivan, Patrick F; State, Matthew W; Weng, Zhiping; Peters, Mette A; White, Kevin P; Gerstein, Mark B; Senthil, Geetha; Lehner, Thomas; Sklar, Pamela; Sestan, Nenad

    2015-01-01

    Recent research on disparate psychiatric disorders has implicated rare variants in genes involved in global gene regulation and chromatin modification, as well as many common variants located primarily in regulatory regions of the genome. Understanding precisely how these variants contribute to disease will require a deeper appreciation for the mechanisms of gene regulation in the developing and adult human brain. The PsychENCODE project aims to produce a public resource of multidimensional genomic data using tissue- and cell type–specific samples from approximately 1,000 phenotypically well-characterized, high-quality healthy and disease-affected human post-mortem brains, as well as functionally characterize disease-associated regulatory elements and variants in model systems. We are beginning with a focus on autism spectrum disorder, bipolar disorder and schizophrenia, and expect that this knowledge will apply to a wide variety of psychiatric disorders. This paper outlines the motivation and design of PsychENCODE. PMID:26605881

  11. Monolithic-integrated microlaser encoder.

    PubMed

    Sawada, R; Higurashi, E; Ito, T; Ohguchi, O; Tsubamoto, M

    1999-11-20

    We have developed an extremely small integrated microencoder whose sides are less than 1 mm long. It is 1/100 the size of conventional encoders. This microencoder consists of a laser diode, monolithic photodiodes, and fluorinated polyimide waveguides with total internal reflection mirrors. The instrument can measure the relative displacement between a grating scale and the encoder with a resolution of the order of 0.01 microm; it can also determine the direction in which the scale is moving. By using the two beams that were emitted from the two etched mirrors of the laser diode, by monolithic integration of the waveguide and photodiodes, and by fabrication of a step at the edge of the waveguide, we were able to eliminate conventional bulky optical components such as the beam splitter, the quarter-wavelength plate, bulky mirrors, and bulky photodetectors. PMID:18324228

  12. Nonconjugative Plasmids Encoding Sulfanilamide Resistance

    PubMed Central

    Mitsuhashi, Susumu; Inoue, Kunio; Inoue, Matsuhisa

    1977-01-01

    Nonconjugative plasmids encoding sulfanilamide (Sa) resistance were demonstrated at a high frequency in Shigella and Escherichia coli strains resistant to sulfanilamide. These Sa plasmids were all compatible with the standard plasmids used in compatibility testing. The sizes of seven Sa plasmids were measured by electron microscopy and ranged from 1.79 to 2.08 μm, corresponding to 3.5 to 3.9 megadaltons. Images PMID:334067

  13. Vector Encoding in Biochemical Networks

    NASA Astrophysics Data System (ADS)

    Potter, Garrett; Sun, Bo

    Encoding of environmental cues via biochemical signaling pathways is of vital importance in the transmission of information for cells in a network. The current literature assumes a single cell state is used to encode information, however, recent research suggests the optimal strategy utilizes a vector of cell states sampled at various time points. To elucidate the optimal sampling strategy for vector encoding, we take an information theoretic approach and determine the mutual information of the calcium signaling dynamics obtained from fibroblast cells perturbed with different concentrations of ATP. Specifically, we analyze the sampling strategies under the cases of fixed and non-fixed vector dimension as well as the efficiency of these strategies. Our results show that sampling with greater frequency is optimal in the case of non-fixed vector dimension but that, in general, a lower sampling frequency is best from both a fixed vector dimension and efficiency standpoint. Further, we find the use of a simple modified Ornstein-Uhlenbeck process as a model qualitatively captures many of our experimental results suggesting that sampling in biochemical networks is based on a few basic components.

  14. Lessons from modENCODE.

    PubMed

    Brown, James B; Celniker, Susan E

    2015-01-01

    The modENCODE (Model Organism Encyclopedia of DNA Elements) Consortium aimed to map functional elements-including transcripts, chromatin marks, regulatory factor binding sites, and origins of DNA replication-in the model organisms Drosophila melanogaster and Caenorhabditis elegans. During its five-year span, the consortium conducted more than 2,000 genome-wide assays in developmentally staged animals, dissected tissues, and homogeneous cell lines. Analysis of these data sets provided foundational insights into genome, epigenome, and transcriptome structure and the evolutionary turnover of regulatory pathways. These studies facilitated a comparative analysis with similar data types produced by the ENCODE Consortium for human cells. Genome organization differs drastically in these distant species, and yet quantitative relationships among chromatin state, transcription, and cotranscriptional RNA processing are deeply conserved. Of the many biological discoveries of the modENCODE Consortium, we highlight insights that emerged from integrative studies. We focus on operational and scientific lessons that may aid future projects of similar scale or aims in other, emerging model systems. PMID:26133010

  15. Hall effect encoding of brushless dc motors

    NASA Technical Reports Server (NTRS)

    Berard, C. A.; Furia, T. J.; Goldberg, E. A.; Greene, R. C.

    1970-01-01

    Encoding mechanism integral to the motor and using the permanent magnets embedded in the rotor eliminates the need for external devices to encode information relating the position and velocity of the rotating member.

  16. Novel optical encoder for harsh environments

    NASA Astrophysics Data System (ADS)

    Kress, Bernard; Mueller, Ulrich; Brac-de-la-Perriere, Vincent

    2014-09-01

    We are presenting a new optical encoder architecture for shaft encoding, both in incremental and absolute modes. This encoder is based on a diffractive optics technology platform. We have developed various disk based rotary diffractive encoders previously. This encoder is different in the way it is not a disk composed of successive gratings or computer generated holograms, but rather composed of a single element placed on the shaft. It is thus best suited for hollow shaft or end of shaft applications such as in encoder controlled electrical motors. This new architecture aims at solving some of the problems encountered with previous implementations of diffractive encoders such as disk wobble, disk to shaft centering and also encoding in harsh environments.

  17. Jam-resistant speech encoding

    NASA Astrophysics Data System (ADS)

    Poole, M. A.; Rifkin, R.

    1983-06-01

    This report describes techniques that provide increased jam resistance for digitized speech. Methods for increasing the jam resistance of pulse code modulated data are analyzed and evaluated in listener tests. Special emphasis is placed on new voice encoding approaches that take advantage of a spread spectrum system with a variable (or multiple)-data-rate/variable (or multiple)-AJ capability. Methods for matching a source to a channel in a jamming environment are investigated. Several techniques that provide about a 4 dB increase in jam resistance have been identified.

  18. Time Course of Grammatical Encoding in Agrammatism

    ERIC Educational Resources Information Center

    Lee, Jiyeon

    2011-01-01

    Producing a sentence involves encoding a preverbal message into a grammatical structure by retrieving lexical items and integrating them into a functional (semantic-to-grammatical) structure. Individuals with agrammatism are impaired in this grammatical encoding process. However, it is unclear what aspect of grammatical encoding is impaired and…

  19. Schematic driven layout of Reed Solomon encoders

    NASA Technical Reports Server (NTRS)

    Arave, Kari; Canaris, John; Miles, Lowell; Whitaker, Sterling

    1992-01-01

    Two Reed Solomon error correcting encoders are presented. Schematic driven layout tools were used to create the encoder layouts. Special consideration had to be given to the architecture and logic to provide scalability of the encoder designs. Knowledge gained from these projects was used to create a more flexible schematic driven layout system.

  20. Angular encoding in attosecond recollision

    NASA Astrophysics Data System (ADS)

    Kitzler, Markus; Xie, Xinhua; Roither, Stefan; Scrinzi, Armin; Baltuska, Andrius

    2008-02-01

    We describe a general concept of using the spatial information encoded in the time-dependent polarization of high harmonic radiation generated by orthogonally polarized two-color laser fields. The main properties of recolliding electron wave packets driven by such fields are reviewed. It is shown that in addition to the recollision energy the angle of recollision of such wave packets, which is directly mapped onto the polarization direction of the emitted high harmonic radiation, varies on a sub-laser-cycle time-scale. Thus, a mapping between the polarization angle and the frequency of the emitted radiation is established on an attosecond time scale. While the polarization angle encodes the spatial properties of the recollision process, the frequency is linked to time via the well-known dispersion relations of high harmonic generation. Based on these principles, we show that in combination with polarization selective detection the use of orthogonally polarized drive pulses for high harmonic generation permit one to construct spatially resolved attosecond measurements. Here, we present two examples of possible applications: (i) a method for isolating a single attosecond pulse from an attosecond pulse train which is more efficient than the cut-off selection method, and (ii) a technique for orbital tomography of molecules with attosecond resolution.

  1. Reconstruction of turbo-code encoders

    NASA Astrophysics Data System (ADS)

    Barbier, Johann

    2005-06-01

    Turbo-code encoders are one of the spreadest family of error correcting codes used in the communication's world, especially in space transmissions. This paper presents an efficient technique to reconstruct turbo-code encoders which allows a passive adversary, with only few bits of an intercepted message encoded by the target turbocode encoder, to determine the parameters of the turbo-code encoder used, and therefore to decode online the communications. Thereby, our results confirm that keeping secret the parameters of turbo-code encoders can not be considered as a cryptographically way to ensure confidentiality. The starting point of our work is algorithms due to Filiol which enable to find the parameters of each convolutional encoder in the turbo-code encoder. Then, we recover the interleaver with two new algorithms, the first one based on the dynamic trie structure and the second one on a first order statistical test. The first algorithm is dedicated to noiseless channels. The asymptotic complexity of the complete process is O(n4) when a n2-bit message is available to attack a n-bit turbo-code encoder. The second algorithm works for every kind of channel and the noise does not matter much. Additionally, we present experimental results which underline the right detection threshold to use to recover the interleaver with a high probability. Furthermore, this method also works for turbo-code encoders composed of punctured convolutional encoders.

  2. Molecular mechanisms for protein-encoded inheritance

    SciTech Connect

    Wiltzius, Jed J.W.; Landau, Meytal; Nelson, Rebecca; Sawaya, Michael R.; Apostol, Marcin I.; Goldschmidt, Lukasz; Soriaga, Angela B.; Cascio, Duilio; Rajashankar, Kanagalaghatta; Eisenberg, David

    2009-12-01

    In prion inheritance and transmission, strains are phenotypic variants encoded by protein 'conformations'. However, it is unclear how a protein conformation can be stable enough to endure transmission between cells or organisms. Here we describe new polymorphic crystal structures of segments of prion and other amyloid proteins, which offer two structural mechanisms for the encoding of prion strains. In packing polymorphism, prion strains are encoded by alternative packing arrangements (polymorphs) of {beta}-sheets formed by the same segment of a protein; in segmental polymorphism, prion strains are encoded by distinct {beta}-sheets built from different segments of a protein. Both forms of polymorphism can produce enduring conformations capable of encoding strains. These molecular mechanisms for transfer of protein-encoded information into prion strains share features with the familiar mechanism for transfer of nucleic acid-encoded information into microbial strains, including sequence specificity and recognition by noncovalent bonds.

  3. Novelty's effect on memory encoding.

    PubMed

    Rangel-Gomez, Mauricio; Janenaite, Sigita; Meeter, Martijn

    2015-07-01

    It is often thought that novelty benefits memory formation. However, support for this idea mostly comes from paradigms that are open to alternative explanations. In the present study we manipulated novelty in a word-learning task through task-irrelevant background images. These background images were either standard (presented repeatedly), or novel (presented only once). Two types of background images were used: Landscape pictures and fractals. EEG was also recorded during encoding. Contrary to the idea that novelty aids memory formation, memory performance was not affected by the novelty of the background. In the evoked response potentials, we found evidence of distracting effects of novelty: both the N1 and P3b components were smaller to words studied with novel backgrounds, and the amplitude of the N2b component correlated negatively with subsequent retrieval. We conclude that although evidence from other studies does suggest benefits on a longer time scale, novelty has no instantaneous benefits for learning. PMID:26005196

  4. Digital plus analog output encoder

    NASA Technical Reports Server (NTRS)

    Hafle, R. S. (Inventor)

    1976-01-01

    The disclosed encoder is adapted to produce both digital and analog output signals corresponding to the angular position of a rotary shaft, or the position of any other movable member. The digital signals comprise a series of binary signals constituting a multidigit code word which defines the angular position of the shaft with a degree of resolution which depends upon the number of digits in the code word. The basic binary signals are produced by photocells actuated by a series of binary tracks on a code disc or member. The analog signals are in the form of a series of ramp signals which are related in length to the least significant bit of the digital code word. The analog signals are derived from sine and cosine tracks on the code disc.

  5. Engineering Genetically Encoded FRET Sensors

    PubMed Central

    Lindenburg, Laurens; Merkx, Maarten

    2014-01-01

    Förster Resonance Energy Transfer (FRET) between two fluorescent proteins can be exploited to create fully genetically encoded and thus subcellularly targetable sensors. FRET sensors report changes in energy transfer between a donor and an acceptor fluorescent protein that occur when an attached sensor domain undergoes a change in conformation in response to ligand binding. The design of sensitive FRET sensors remains challenging as there are few generally applicable design rules and each sensor must be optimized anew. In this review we discuss various strategies that address this shortcoming, including rational design approaches that exploit self-associating fluorescent domains and the directed evolution of FRET sensors using high-throughput screening. PMID:24991940

  6. Euphausiid distribution along the Western Antarctic Peninsula—Part A: Development of robust multi-frequency acoustic techniques to identify euphausiid aggregations and quantify euphausiid size, abundance, and biomass

    NASA Astrophysics Data System (ADS)

    Lawson, Gareth L.; Wiebe, Peter H.; Stanton, Timothy K.; Ashjian, Carin J.

    2008-02-01

    Methods were refined and tested for identifying the aggregations of Antarctic euphausiids ( Euphausia spp.) and then estimating euphausiid size, abundance, and biomass, based on multi-frequency acoustic survey data. A threshold level of volume backscattering strength for distinguishing euphausiid aggregations from other zooplankton was derived on the basis of published measurements of euphausiid visual acuity and estimates of the minimum density of animals over which an individual can maintain visual contact with its nearest neighbor. Differences in mean volume backscattering strength at 120 and 43 kHz further served to distinguish euphausiids from other sources of scattering. An inversion method was then developed to estimate simultaneously the mean length and density of euphausiids in these acoustically identified aggregations based on measurements of mean volume backscattering strength at four frequencies (43, 120, 200, and 420 kHz). The methods were tested at certain locations within an acoustically surveyed continental shelf region in and around Marguerite Bay, west of the Antarctic Peninsula, where independent evidence was also available from net and video systems. Inversion results at these test sites were similar to net samples for estimated length, but acoustic estimates of euphausiid density exceeded those from nets by one to two orders of magnitude, likely due primarily to avoidance and to a lesser extent to differences in the volumes sampled by the two systems. In a companion study, these methods were applied to the full acoustic survey data in order to examine the distribution of euphausiids in relation to aspects of the physical and biological environment [Lawson, G.L., Wiebe, P.H., Ashjian, C.J., Stanton, T.K., 2008. Euphausiid distribution along the Western Antarctic Peninsula—Part B: Distribution of euphausiid aggregations and biomass, and associations with environmental features. Deep-Sea Research II, this issue [doi:10.1016/j.dsr2.2007.11.014

  7. The potential of at-home prediction of the formation of urolithiasis by simple multi-frequency electrical conductivity of the urine and the comparison of its performance with urine ion-related indices, color and specific gravity.

    PubMed

    Silverio, Angelito A; Chung, Wen-Yaw; Cheng, Cheanyeh; Wang, Hai-Lung; Kung, Chien-Min; Chen, Jun; Tsai, Vincent F S

    2016-04-01

    It is important to control daily diet, water intake and life style as well as monitor the quality of urine for urolithiasis prevention. For decades, many ion-related indices have been developed for predicting the formation of urinary stones or urolithiasis, such as EQUILs, relative supersaturation (RSS), Tiselius indices (TI), Robertson risk factor algorithms (RRFA) and more recently, the Bonn risk index. However, they mostly demand robust laboratory analysis, are work-intensive, and even require complex computational programs to get the concentration patterns of several urine analytes. A simple and fast platform for measuring multi-frequency electrical conductivity (MFEC) of morning spot urine (random urine) to predict the onset of urolithiasis was implemented in this study. The performance thereof was compared to ion-related indices, urine color and specific gravity. The concentrations of relevant ions, color, specific gravity (SG) and MFEC (MFEC tested at 1, 10, 100, 5001 KHz and 1 MHz) of 80 random urine samples were examined after collection. Then, the urine samples were stored at 4 °C for 24 h to determine whether sedimentation would occur or not. Ion-activity product index of calcium oxalate (AP(CaOx) EQ2) was calculated. The correlation between AP(CaOx) EQ2, urine color, SG and MFEC were analyzed. AP(CaOx) EQ2, urine color and MFEC (at 5 frequencies) all demonstrated good prediction (p = 0.01, 0.01, 0.01, respectively) for stone formation. The positive correlation between AP(CaOx) EQ2 and MFEC is also significant (p = 0.01). MFEC provides a good metric for predicting the onset of urolithiasis, which is comparable to conventional ion-related indices and urine color. This technology can be implemented with much ease for objectively monitoring the quality of urine at points-of-care or at home. PMID:26271351

  8. Control Circuit For Reed-Solomon Encoder

    NASA Technical Reports Server (NTRS)

    Ross, Douglas

    1992-01-01

    Control circuit designed for use with commercially available AHA4610 Reed-Solomon encoder. Needed to select depth of interleaving and to synchronize input and output blocks of data and parity bits with suitable clock signals. Circuit provides synchronizing and control signals for Reed-Solomon encoder. Encoder can operate with asynchronous input and output data streams at rates up to 80 Mb/s. Interleaving depth selectable, and accommodation to input data rate automatic.

  9. NMDA receptors and memory encoding.

    PubMed

    Morris, Richard G M

    2013-11-01

    It is humbling to think that 30 years have passed since the paper by Collingridge, Kehl and McLennan showing that one of Jeff Watkins most interesting compounds, R-2-amino-5-phosphonopentanoate (d-AP5), blocked the induction of long-term potentiation in vitro at synapses from area CA3 of the hippocampus to CA1 without apparent effect on baseline synaptic transmission (Collingridge et al., 1983). This dissociation was one of the key triggers for an explosion of interest in glutamate receptors, and much has been discovered since that collectively contributes to our contemporary understanding of glutamatergic synapses - their biophysics and subunit composition, of the agonists and antagonists acting on them, and their diverse functions in different networks of the brain and spinal cord. It can be fairly said that Collingridge et al.'s (1983) observation was the stimulus that has led, on the one hand, to structural biological work at the atomic scale describing the key features of NMDA receptors that enables their coincidence function to happen; and, on the other, to work with whole animals investigating the contributions that calcium signalling via this receptor can have on rhythmical activities controlled by spinal circuits, memory encoding in the hippocampus (the topic of this article), visual cortical plasticity, sensitization in pain, and other functions. In this article, I lay out how my then interest in long-term potentiation (LTP) as a model of memory enabled me to recognise the importance of Collingridge et al.'s discovery - and how I and my colleagues endeavoured to take things forward in the area of learning and memory. This is in some respects a personal story, and I tell it as such. The idea that NMDA receptor activation is essential for memory encoding, though not for storage, took time to develop and to be accepted. Along the way, there have been confusions, challenges, and surprises surrounding the idea that activation of NMDA receptors can

  10. Unconscious relational encoding depends on hippocampus

    PubMed Central

    Duss, Simone B.; Reber, Thomas P.; Hänggi, Jürgen; Schwab, Simon; Wiest, Roland; Müri, René M.; Brugger, Peter; Gutbrod, Klemens

    2014-01-01

    Textbooks divide between human memory systems based on consciousness. Hippocampus is thought to support only conscious encoding, while neocortex supports both conscious and unconscious encoding. We tested whether processing modes, not consciousness, divide between memory systems in three neuroimaging experiments with 11 amnesic patients (mean age = 45.55 years, standard deviation = 8.74, range = 23–60) and 11 matched healthy control subjects. Examined processing modes were single item versus relational encoding with only relational encoding hypothesized to depend on hippocampus. Participants encoded and later retrieved either single words or new relations between words. Consciousness of encoding was excluded by subliminal (invisible) word presentation. Amnesic patients and controls performed equally well on the single item task activating prefrontal cortex. But only the controls succeeded on the relational task activating the hippocampus, while amnesic patients failed as a group. Hence, unconscious relational encoding, but not unconscious single item encoding, depended on hippocampus. Yet, three patients performed normally on unconscious relational encoding in spite of amnesia capitalizing on spared hippocampal tissue and connections to language cortex. This pattern of results suggests that processing modes divide between memory systems, while consciousness divides between levels of function within a memory system. PMID:25273998

  11. Encoders for block-circulant LDPC codes

    NASA Technical Reports Server (NTRS)

    Andrews, Kenneth; Dolinar, Sam; Thorpe, Jeremy

    2005-01-01

    In this paper, we present two encoding methods for block-circulant LDPC codes. The first is an iterative encoding method based on the erasure decoding algorithm, and the computations required are well organized due to the block-circulant structure of the parity check matrix. The second method uses block-circulant generator matrices, and the encoders are very similar to those for recursive convolutional codes. Some encoders of the second type have been implemented in a small Field Programmable Gate Array (FPGA) and operate at 100 Msymbols/second.

  12. Perceptually adapted MPEG video encoding

    NASA Astrophysics Data System (ADS)

    Bordes, Philippe; Guillotel, Philippe

    2000-06-01

    In picture quality assessment, the amount of distortion perceived by a human observer differs from one region to another according to its particular local content. This subjective perception can be explained/predicted by considering some simple psychovisual properties (masking) of the Human Visual System (HVS). We have implemented a HVS model based on a pyramid decomposition for extracting the spatial frequencies, associated with a multi-resolution motion representation. Then the visibility of the decoded errors is computed by exploiting the Kelly's contrast sensitivity spatio-velocity model. The resulting data is called a 'Quality-map.' Special attention has been paid to temporal/moving effects since, in the case of video sequences, motion strongly influences the subjective quality assessment. The quality of the motion information is thus preponderant. In the second part, two possible uses of these psychovisual properties for improving MPEG video encoding performances are depicted: (1) The pre-processing of the pictures to remove non-visible information using a motion adapted filtering. This process is efficient in term of bits saved and degradation is not significant especially on consumer electronic TV sets. (2) A perceptual quantizer based on a local adaptation scheme in order to obtain Quality-maps as uniform as possible (homogeneous perceived distortion), at constant bit-rate. Further improvements have been considered, especially when the viewer is tracking a moving object in the scene.

  13. Evaluation of GOES encoder lamps

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Helmold, N.

    1983-01-01

    Aging characteristics and life expectancies of flight quality, tungsten filament, encoder lamps are similar to those of 'commercial' grade gas filled lamps of similar construction, filament material and filament temperature. The aging and final failure by filament burnout are caused by single crystal growth over large portions of the filament with the concomitant development of facets and notches resulting in reduction of cross section and mechanical weakening of the filament. The life expectancy of presently produced lamps is about one year at their nominal operating voltage of five volts dc. At 4.5 volts, it is about two years. These life times are considerably shorter, and the degradation rates of lamp current and light flux are considerably higher, than were observed in the laboratory and in orbit on lamps of the same type manufactured more than a decade ago. It is speculated that the filaments of these earlier lamps contained a crystallization retarding dopant, possibly thorium oxide. To obtain the desired life expectancy of or = to four years in present lamps, operating voltages of or = to four volts dc would be required.

  14. Encoding and decoding in fMRI

    PubMed Central

    Naselaris, Thomas; Kay, Kendrick N.; Nishimoto, Shinji; Gallant, Jack L.

    2010-01-01

    Over the past decade fMRI researchers have developed increasingly sensitive techniques for analyzing the information represented in BOLD activity. The most popular of these techniques is linear classification, a simple technique for decoding information about experimental stimuli or tasks from patterns of activity across an array of voxels. A more recent development is the voxel-based encoding model, which describes the information about the stimulus or task that is represented in the activity of single voxels. Encoding and decoding are complementary operations: encoding uses stimuli to predict activity while decoding uses activity to predict information about stimuli. However, in practice these two operations are often confused, and their respective strengths and weaknesses have not been made clear. Here we use the concept of a linearizing feature space to clarify the relationship between encoding and decoding. We show that encoding and decoding operations can both be used to investigate some of the most common questions about how information is represented in the brain. However, focusing on encoding models offers two important advantages over decoding. First, an encoding model can in principle provide a complete functional description of a region of interest, while a decoding model can provide only a partial description. Second, while it is straightforward to derive an optimal decoding model from an encoding model it is much more difficult to derive an encoding model from a decoding model. We propose a systematic modeling approach that begins by estimating an encoding model for every voxel in a scan and ends by using the estimated encoding models to perform decoding. PMID:20691790

  15. Is the Wilkins Ice Shelf a Firn Aquifer? Spaceborne Observation of Subsurface Winter Season Liquid Meltwater Storage on the Antarctic Peninsula using Multi-Frequency Active and Passive Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Miller, J.; Scambos, T.; Forster, R. R.; Long, D. G.; Ligtenberg, S.; van den Broeke, M.; Vaughan, D. G.

    2015-12-01

    Near-surface liquid meltwater on ice shelves has been inferred to influence ice shelf stability if it induces hydrofracture and is linked to disintegration events on the Larsen B and the Wilkins ice shelves on the Antarctic Peninsula during the summer months. While the initial Wilkins disintegration event occurred in March of 2009, two smaller disintegration events followed in May and in July of that year. It has long been assumed meltwater refreezes soon after surface melt processes cease. Given this assumption, an earlier hypothesis for the two winter season disintegration events was hydrofracture via a brine infiltration layer. Two lines of evidence supported this hypothesis 1) early airborne radar surveys did not record a reflection from the bottom of the ice shelf, and 2) a shallow core drilled in 1972 on the Wilkins encountered liquid water at a depth of ~7 m. The salinity of the water and the temperature at the base of the core, however, were not described. The recent discovery of winter season liquid meltwater storage on the Greenland ice sheet has changed perceptions on meltwater longevity at depth in firn. Evidence of Greenland's firn aquifer includes liquid meltwater encountered in shallow firn cores at 5 m depth and a lack of reflections from the base of the ice sheet in airborne surveys. Thus, previous lines of evidence suggesting brine infiltration may alternatively suggest the presence of a perennial firn aquifer. We recently demonstrated the capability for observation of Greenland's firn aquifer from space using multi-frequency active and passive microwave remote sensing. This research exploits the retrieval technique developed for Greenland to provide the first spaceborne mappings of winter season liquid meltwater storage on the Wilkins. We combine L-band brightness temperature and backscatter data from the MIRAS instrument (1.4 GHz) aboard ESA's Soil Moisture and Ocean Salinity mission and the radar (1.3 GHZ) and radiometer(1.4 GHz) aboard NASA

  16. Experiments in encoding multilevel images as quadtrees

    NASA Technical Reports Server (NTRS)

    Lansing, Donald L.

    1987-01-01

    Image storage requirements for several encoding methods are investigated and the use of quadtrees with multigray level or multicolor images are explored. The results of encoding a variety of images having up to 256 gray levels using three schemes (full raster, runlength and quadtree) are presented. Although there is considerable literature on the use of quadtrees to store and manipulate binary images, their application to multilevel images is relatively undeveloped. The potential advantage of quadtree encoding is that an entire area with a uniform gray level may be encoded as a unit. A pointerless quadtree encoding scheme is described. Data are presented on the size of the quadtree required to encode selected images and on the relative storage requirements of the three encoding schemes. A segmentation scheme based on the statistical variation of gray levels within a quadtree quadrant is described. This parametric scheme may be used to control the storage required by an encoded image and to preprocess a scene for feature identification. Several sets of black and white and pseudocolor images obtained by varying the segmentation parameter are shown.

  17. The Acquisition of Syntactically Encoded Evidentiality

    ERIC Educational Resources Information Center

    Rett, Jessica; Hyams, Nina

    2014-01-01

    This article presents several empirical studies of syntactically encoded evidentiality in English. The first part of our study consists of an adult online experiment that confirms claims in Asudeh & Toivonen (2012) that raised Perception Verb Similatives (PVSs; e.g. "John looks like he is sick") encode direct evidentiality. We then…

  18. Congruity of Encoding in Children's Redintegrative Memory.

    ERIC Educational Resources Information Center

    Hall, Donald M.; Geis, Mary Fulcher

    The mnemonic consequences of semantic, acoustic, and orthographic encoding and the relationships between encoding and retrieval cues were investigated in an incidental-learning experiment involving 24 first-, third-, and fifth-grade pupils. Each child was asked one orienting question for each of 18 words; the questions differed in the type of…

  19. 47 CFR 11.32 - EAS Encoder.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for either manual or automatic operation. (2) Inputs. The encoder shall have two inputs, one for audio... encoder shall have two outputs, one audio port and one data port (RS-232C with standard protocol and 1200... frequency components outside 200 to 4000 Hz shall be attenuated by 40 dB or more with respect to the...

  20. Encoding information using Laguerre Gaussian modes

    NASA Astrophysics Data System (ADS)

    Trichili, Abderrahmen; Dudley, Angela; Ben Salem, Amine; Ndagano, Bienvenu; Zghal, Mourad; Forbes, Andrew

    2015-08-01

    We experimentally demonstrate an information encoding protocol using the two degrees of freedom of Laguerre Gaussian modes having different radial and azimuthal components. A novel method, based on digital holography, for information encoding and decoding using different data transmission scenarios is presented. The effects of the atmospheric turbulence introduced in free space communication is discussed as well.

  1. DNA encoding a DNA repair protein

    DOEpatents

    Petrini, John H.; Morgan, William Francis; Maser, Richard Scott; Carney, James Patrick

    2006-08-15

    An isolated and purified DNA molecule encoding a DNA repair protein, p95, is provided, as is isolated and purified p95. Also provided are methods of detecting p95 and DNA encoding p95. The invention further provides p95 knock-out mice.

  2. Industrial Applications Of Optical Shaft Encoders

    NASA Astrophysics Data System (ADS)

    Edmister, Brian W.

    1980-11-01

    The development of the microprocessor and mini-computer for industrial process control has made the optical shaft angle encoder a natural choice for a position feedback transducer. Many of these applications, however, require the encoder to operate reliably in extremely hostile environments. In response to this, the encoder manufacturer has been faced with reliability problems which fall into the following general categories: 1. Exposure to weather 2. Wide operating and storage temperature range 3. Exposure to corrosive chemicals 4. Severe shock and vibration 5. High electrical noise levels 6. Severe blows to encoder housing 7. Operation in explosive atmospheres Three of these applications expose the encoder to most of these environmental conditions: 1. A jack-up control position feedback for an offshore oil well drilling rig 2. A depth measurement system for oil well logging instrumentation 3. Elevation and azimuth feedback for a solar power plant heliostat

  3. Programmable Pulse-Position-Modulation Encoder

    NASA Technical Reports Server (NTRS)

    Zhu, David; Farr, William

    2006-01-01

    A programmable pulse-position-modulation (PPM) encoder has been designed for use in testing an optical communication link. The encoder includes a programmable state machine and an electronic code book that can be updated to accommodate different PPM coding schemes. The encoder includes a field-programmable gate array (FPGA) that is programmed to step through the stored state machine and code book and that drives a custom high-speed serializer circuit board that is capable of generating subnanosecond pulses. The stored state machine and code book can be updated by means of a simple text interface through the serial port of a personal computer.

  4. Source encoding for orbiter communications links

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The feasibility of using data compression to improve link efficiency as an alternative to increased transmitter power, reducing receiver noise figures, increasing antenna gain through more stringent orbiter attitude constraints, etc. is studied. A method of encoding digital data is developed which permits low band-width encoding as well as a unique system of adaptive run length encoding. The effectiveness of these techniques for the air-to-ground link and for the bandwidth-limited ground-to-ground data link used for the orbiter downlink data is evaluated. Results are presented.

  5. Pulse Vector-Excitation Speech Encoder

    NASA Technical Reports Server (NTRS)

    Davidson, Grant; Gersho, Allen

    1989-01-01

    Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.

  6. VLSI Reed-Solomon Encoder With Interleaver

    NASA Technical Reports Server (NTRS)

    Hsu, In-Shek; Deutsch, L. J.; Truong, Trieu-Kie; Reed, I. S.

    1990-01-01

    Size, weight, and susceptibility to burst errors reduced. Encoding system built on single very-large-scale integrated (VLSI) circuit chip produces (255,223) Reed-Solomon (RS) code with programmable interleaving up to depth of 5. (225,223) RS encoder includes new remainder-and-interleaver unit providing programmable interleaving of code words. Remainder-and-interleaver unit contains shift registers and modulo-2 adders. Signals on "turn" and "no-turn" lines control depth of interleaving. Based on E. R. Berlekamp's bit-serial multiplication algorithm for (225,223) RS encoder over Galois Field (2 to the 8th power).

  7. Phase function encoding of diffractive structures.

    PubMed

    Schilling, A; Herzig, H P

    2000-10-10

    We analyzed the direct sampling (DS) method for diffractive lens encoding, using exact electromagnetic diffraction theory. In addition to previously published research [Pure Appl. Opt. 7, 565 (1998)] we present what we believe to be new results for TM polarization. We found that the validity of the scalar-based DS method is even more extended for TM than for TE polarization. Additionally, we fabricated and characterized DS-encoded blazed gratings and found good agreement between the experimental and theoretical diffraction efficiencies. We analyzed quantitatively the influence of the encoding schemes DS and analytic quantization (AQ) on the quality of the focal spot. We also investigated the focal spot sizes (FWHM) and the Strehl ratios of the DS- and the AQ-encoded cylindrical lenses. PMID:18354523

  8. Cellobiohydrolase variants and polynucleotides encoding same

    DOEpatents

    Wogulis, Mark

    2013-09-24

    The present invention relates to variants of a parent cellobiohydrolase II. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.

  9. Cellobiohydrolase variants and polynucleotides encoding the same

    DOEpatents

    Wogulis, Mark

    2014-09-09

    The present invention relates to variants of a parent cellobiohydrolase. The present invention also relates to polynucleotides encoding the cellobiohydrolase variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the cellobiohydrolase variants.

  10. Cellobiohydrolase variants and polynucleotides encoding same

    SciTech Connect

    Wogulis, Mark

    2014-10-14

    The present invention relates to variants of a parent cellobiohydrolase II. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.

  11. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  12. Encoding and decoding of femtosecond pulses.

    PubMed

    Weiner, A M; Heritage, J P; Salehi, J A

    1988-04-01

    We demonstrate the spreading of femtosecond optical pulses into picosecond-duration pseudonoise bursts. Spreading is accomplished by encoding pseudorandom binary phase codes onto the optical frequency spectrum. Subsequent decoding of the spectral phases restores the original pulse. We propose that frequency-domain encoding and decoding of coherent ultrashort pulses could form the basis for a rapidly reconfigurable, code-division multiple-access optical telecommunications network. PMID:19745879

  13. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, D.B.; Lao, G.

    1998-01-06

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium. 3 figs.

  14. Navigating and Mining modENCODE Data

    PubMed Central

    Boley, Nathan; Wan, Kenneth H.; Bickel, Peter J.; Celniker, Susan E.

    2014-01-01

    modENCODE was a 5 yr NHGRI funded project (2007– 2012) to map the function of every base in the genomes of worms and flies characterizing positions of modified histones and other chromatin marks, origins of DNA replication, RNA transcripts and the transcription factor binding sites that control gene expression. Here we describe the Drosophila modENCODE datasets and how best to access and use them for genome wide and individual gene studies. PMID:24636835

  15. Neurally Encoding Time for Olfactory Navigation

    PubMed Central

    Park, In Jun; Hein, Andrew M.; Bobkov, Yuriy V.; Reidenbach, Matthew A.; Ache, Barry W.; Principe, Jose C.

    2016-01-01

    Accurately encoding time is one of the fundamental challenges faced by the nervous system in mediating behavior. We recently reported that some animals have a specialized population of rhythmically active neurons in their olfactory organs with the potential to peripherally encode temporal information about odor encounters. If these neurons do indeed encode the timing of odor arrivals, it should be possible to demonstrate that this capacity has some functional significance. Here we show how this sensory input can profoundly influence an animal’s ability to locate the source of odor cues in realistic turbulent environments—a common task faced by species that rely on olfactory cues for navigation. Using detailed data from a turbulent plume created in the laboratory, we reconstruct the spatiotemporal behavior of a real odor field. We use recurrence theory to show that information about position relative to the source of the odor plume is embedded in the timing between odor pulses. Then, using a parameterized computational model, we show how an animal can use populations of rhythmically active neurons to capture and encode this temporal information in real time, and use it to efficiently navigate to an odor source. Our results demonstrate that the capacity to accurately encode temporal information about sensory cues may be crucial for efficient olfactory navigation. More generally, our results suggest a mechanism for extracting and encoding temporal information from the sensory environment that could have broad utility for neural information processing. PMID:26730727

  16. Neurally Encoding Time for Olfactory Navigation.

    PubMed

    Park, In Jun; Hein, Andrew M; Bobkov, Yuriy V; Reidenbach, Matthew A; Ache, Barry W; Principe, Jose C

    2016-01-01

    Accurately encoding time is one of the fundamental challenges faced by the nervous system in mediating behavior. We recently reported that some animals have a specialized population of rhythmically active neurons in their olfactory organs with the potential to peripherally encode temporal information about odor encounters. If these neurons do indeed encode the timing of odor arrivals, it should be possible to demonstrate that this capacity has some functional significance. Here we show how this sensory input can profoundly influence an animal's ability to locate the source of odor cues in realistic turbulent environments-a common task faced by species that rely on olfactory cues for navigation. Using detailed data from a turbulent plume created in the laboratory, we reconstruct the spatiotemporal behavior of a real odor field. We use recurrence theory to show that information about position relative to the source of the odor plume is embedded in the timing between odor pulses. Then, using a parameterized computational model, we show how an animal can use populations of rhythmically active neurons to capture and encode this temporal information in real time, and use it to efficiently navigate to an odor source. Our results demonstrate that the capacity to accurately encode temporal information about sensory cues may be crucial for efficient olfactory navigation. More generally, our results suggest a mechanism for extracting and encoding temporal information from the sensory environment that could have broad utility for neural information processing. PMID:26730727

  17. Multichannel Compressive Sensing MRI Using Noiselet Encoding

    PubMed Central

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding. PMID:25965548

  18. Multi-dimensionally encoded magnetic resonance imaging

    PubMed Central

    Lin, Fa-Hsuan

    2013-01-01

    Magnetic resonance imaging typically achieves spatial encoding by measuring the projection of a q-dimensional object over q-dimensional spatial bases created by linear spatial encoding magnetic fields (SEMs). Recently, imaging strategies using nonlinear SEMs have demonstrated potential advantages for reconstructing images with higher spatiotemporal resolution and reducing peripheral nerve stimulation. In practice, nonlinear SEMs and linear SEMs can be used jointly to further improve the image reconstruction performance. Here we propose the multi-dimensionally encoded (MDE) MRI to map a q-dimensional object onto a p-dimensional encoding space where p > q. MDE MRI is a theoretical framework linking imaging strategies using linear and nonlinear SEMs. Using a system of eight surface SEM coils with an eight-channel RF coil array, we demonstrate the five-dimensional MDE MRI for a two-dimensional object as a further generalization of PatLoc imaging and O-space imaging. We also present a method of optimizing spatial bases in MDE MRI. Results show that MDE MRI with a higher dimensional encoding space can reconstruct images more efficiently and with a smaller reconstruction error when the k-space sampling distribution and the number of samples are controlled. PMID:22926830

  19. Prediction in Annotation Based Guideline Encoding

    PubMed Central

    Hagerty, C. Greg; Pickens, David S.; Chang, Jaime; Kulikowski, Casimir A.; Sonnenberg, Frank A.

    2006-01-01

    The encoding of clinical practice guidelines into machine operable representations poses numerous challenges and will require considerable human intervention for the foreseeable future. To assist and potentially speed up this process, we have developed an incremental approach to guideline encoding which begins with the annotation of the original guideline text using markup techniques. A modular and flexible sequence of subtasks results in increasingly inter-operable representations while maintaining the connections to all prior source representations and supporting knowledge. To reduce the encoding bottleneck we also employ a number of machine-assisted learning and prediction techniques within a knowledge-based software environment. Promising results with a straightforward incremental learning algorithm illustrate the feasibility of such an approach. PMID:17238354

  20. Noise level and MPEG-2 encoder statistics

    NASA Astrophysics Data System (ADS)

    Lee, Jungwoo

    1997-01-01

    Most software in the movie and broadcasting industries are still in analog film or tape format, which typically contains random noise that originated from film, CCD camera, and tape recording. The performance of the MPEG-2 encoder may be significantly degraded by the noise. It is also affected by the scene type that includes spatial and temporal activity. The statistical property of noise originating from camera and tape player is analyzed and the models for the two types of noise are developed. The relationship between the noise, the scene type, and encoder statistics of a number of MPEG-2 parameters such as motion vector magnitude, prediction error, and quant scale are discussed. This analysis is intended to be a tool for designing robust MPEG encoding algorithms such as preprocessing and rate control.

  1. Galileo high-resolution encoder system

    NASA Astrophysics Data System (ADS)

    Mancini, Dario; Cascone, Enrico; Schipani, Pietro

    1997-09-01

    The Galileo National Telescope (TNG) is a 3.6 meter Alt-Az telescope installed at the Astronomical Observatory of the Roque de Los Muchachos in La Palma, Canary Islands (Spain). The TNG motion control system, designed and realized by the Technology Working Group (TWG), is completely digital because of the versatility of this system topology. In a digital control system using an encoder as transducer means to have a digital feedback signal, therefore directly comparable with the reference without any conversion that is essential with other kinds of transducers. In the following the Galileo telescope (TNG) encoder system with its control electronics and the management software are described. It has been realized by a collaboration between the Heidenhain Company and the TWG. The TNG encoder system, at the state of the art, has one of the highest performances in the telescopes field, in terms of resolution, accuracy, readout time, reliability.

  2. Interoperability in encoded quantum repeater networks

    NASA Astrophysics Data System (ADS)

    Nagayama, Shota; Choi, Byung-Soo; Devitt, Simon; Suzuki, Shigeya; Van Meter, Rodney

    2016-04-01

    The future of quantum repeater networking will require interoperability between various error-correcting codes. A few specific code conversions and even a generalized method are known, however, no detailed analysis of these techniques in the context of quantum networking has been performed. In this paper we analyze a generalized procedure to create Bell pairs encoded heterogeneously between two separate codes used often in error-corrected quantum repeater network designs. We begin with a physical Bell pair and then encode each qubit in a different error-correcting code, using entanglement purification to increase the fidelity. We investigate three separate protocols for preparing the purified encoded Bell pair. We calculate the error probability of those schemes between the Steane [[7,1,3

  3. Template based low data rate speech encoder

    NASA Astrophysics Data System (ADS)

    Fransen, Lawrence

    1993-09-01

    The 2400-b/s linear predictive coder (LPC) is currently being widely deployed to support tactical voice communication over narrowband channels. However, there is a need for lower-data-rate voice encoders for special applications: improved performance in high bit-error conditions, low-probability-of-intercept (LPI) voice communication, and narrowband integrated voice/data systems. An 800-b/s voice encoding algorithm is presented which is an extension of the 2400-b/s LPC. To construct template tables, speech samples of 420 speakers uttering 8 sentences each were excerpted from the Texas Instrument - Massachusetts Institute of Technology (TIMIT) Acoustic-Phonetic Speech Data Base. Speech intelligibility of the 800-b/s voice encoding algorithm measured by the diagnostic rhyme test (DRT) is 91.5 for three male speakers. This score compares favorably with the 2400-b/s LPC of a few years ago.

  4. An Information Theoretic Characterisation of Auditory Encoding

    PubMed Central

    Overath, Tobias; Cusack, Rhodri; Kumar, Sukhbinder; von Kriegstein, Katharina; Warren, Jason D; Grube, Manon; Carlyon, Robert P; Griffiths, Timothy D

    2007-01-01

    The entropy metric derived from information theory provides a means to quantify the amount of information transmitted in acoustic streams like speech or music. By systematically varying the entropy of pitch sequences, we sought brain areas where neural activity and energetic demands increase as a function of entropy. Such a relationship is predicted to occur in an efficient encoding mechanism that uses less computational resource when less information is present in the signal: we specifically tested the hypothesis that such a relationship is present in the planum temporale (PT). In two convergent functional MRI studies, we demonstrated this relationship in PT for encoding, while furthermore showing that a distributed fronto-parietal network for retrieval of acoustic information is independent of entropy. The results establish PT as an efficient neural engine that demands less computational resource to encode redundant signals than those with high information content. PMID:17958472

  5. Glutamine Flux Imaging Using Genetically Encoded Sensors

    PubMed Central

    Besnard, Julien; Okumoto, Sakiko

    2014-01-01

    Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. A tremendous variety of such sensors for biological molecules became available in the past 15 years, some of which became indispensable tools that are used routinely in many laboratories. One of the exciting applications of genetically encoded sensors is the use of these sensors in investigating cellular transport processes. Properties of transporters such as kinetics and substrate specificities can be investigated at a cellular level, providing possibilities for cell-type specific analyses of transport activities. In this article, we will demonstrate how transporter dynamics can be observed using genetically encoded glutamine sensor as an example. Experimental design, technical details of the experimental settings, and considerations for post-experimental analyses will be discussed. PMID:25146898

  6. A Metric Encoding for Bounded Model Checking

    NASA Astrophysics Data System (ADS)

    Pradella, Matteo; Morzenti, Angelo; San Pietro, Pierluigi

    In Bounded Model Checking, both the system model and the checked property are translated into a Boolean formula to be analyzed by a SAT-solver. We introduce a new encoding technique which is particularly optimized for managing quantitative future and past metric temporal operators, typically found in properties of hard real time systems. The encoding is simple and intuitive in principle, but it is made more complex by the presence, typical of the Bounded Model Checking technique, of backward and forward loops used to represent an ultimately periodic infinite domain by a finite structure. We report and comment on the new encoding technique and on an extensive set of experiments carried out to assess its feasibility and effectiveness.

  7. Quantum repeater with continuous variable encoding

    NASA Astrophysics Data System (ADS)

    Li, Linshu; Albert, Victor V.; Michael, Marios; Muralidharan, Sreraman; Zou, Changling; Jiang, Liang

    2016-05-01

    Quantum communication enables faithful quantum state transfer between different parties and protocols for cryptographic purposes. However, quantum communication over long distances (>1000km) remains challenging due to optical channel attenuation. This calls for investigation on developing novel encoding schemes that correct photon loss errors efficiently. In this talk, we introduce the generalization of multi-component Schrödinger cat states and propose to encode quantum information in these cat states for ultrafast quantum repeaters. We detail the quantum error correction procedures at each repeater station and characterize the performance of this novel encoding scheme given practical imperfections, such as coupling loss. A comparison with other quantum error correcting codes for bosonic modes will be discussed.

  8. Structure and strategy in encoding simplified graphs

    NASA Technical Reports Server (NTRS)

    Schiano, Diane J.; Tversky, Barbara

    1992-01-01

    Tversky and Schiano (1989) found a systematic bias toward the 45-deg line in memory for the slopes of identical lines when embedded in graphs, but not in maps, suggesting the use of a cognitive reference frame specifically for encoding meaningful graphs. The present experiments explore this issue further using the linear configurations alone as stimuli. Experiments 1 and 2 demonstrate that perception and immediate memory for the slope of a test line within orthogonal 'axes' are predictable from purely structural considerations. In Experiments 3 and 4, subjects were instructed to use a diagonal-reference strategy in viewing the stimuli, which were described as 'graphs' only in Experiment 3. Results for both studies showed the diagonal bias previously found only for graphs. This pattern provides converging evidence for the diagonal as a cognitive reference frame in encoding linear graphs, and demonstrates that even in highly simplified displays, strategic factors can produce encoding biases not predictable solely from stimulus structure alone.

  9. Single echo acquisition MRI using RF encoding.

    PubMed

    Wright, Steven M; McDougall, Mary Preston

    2009-11-01

    Encoding of spatial information in magnetic resonance imaging is conventionally accomplished by using magnetic field gradients. During gradient encoding, the position in k-space is determined by a time-integral of the gradient field, resulting in a limitation in imaging speed due to either gradient power or secondary effects such as peripheral nerve stimulation. Partial encoding of spatial information through the sensitivity patterns of an array of coils, known as parallel imaging, is widely used to accelerate the imaging, and is complementary to gradient encoding. This paper describes the one-dimensional limit of parallel imaging in which all spatial localization in one dimension is performed through encoding by the radiofrequency (RF) coil. Using a one-dimensional array of long and narrow parallel elements to localize the image information in one direction, an entire image is obtained from a single line of k-space, avoiding rapid or repeated manipulation of gradients. The technique, called single echo acquisition (SEA) imaging, is described, along with the need for a phase compensation gradient pulse to counteract the phase variation contained in the RF coil pattern which would otherwise cause signal cancellation in each imaging voxel. Image reconstruction and resolution enhancement methods compatible with the speed of the technique are discussed. MR movies at frame rates of 125 frames per second are demonstrated, illustrating the ability to monitor the evolution of transverse magnetization to steady state during an MR experiment as well as demonstrating the ability to image rapid motion. Because this technique, like all RF encoding approaches, relies on the inherent spatially varying pattern of the coil and is not a time-integral, it should enable new applications for MRI that were previously inaccessible due to speed constraints, and should be of interest as an approach to extending the limits of detection in MR imaging. PMID:19441080

  10. Optical encoder based on a nondiffractive beam

    NASA Astrophysics Data System (ADS)

    Lutenberg, A.; Perez Quintián, F.; Rebollo, M. A.

    2007-09-01

    Nowadays most industrial and laboratory motion measuring equipment makes use of optical encoders to measure rotation and linear displacements with sub-micrometrical resolution. In this work we introduce a new design of an optical encoder based on a non diffractive beam, a binary amplitude grating and a monolithic photodetector. Two theoretical models of the system are proposed and implemented to obtain numerical results. The performance of the design is also investigated through experimental measurements. Finally, the experimental results are compared with the models predictions.