WorldWideScience

Sample records for carrier frequency radio-over-fibre

  1. Digital coherent detection of multi-gigabit 40 GHz carrier frequency radio-over-fibre signals using photonic downconversion

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Tafur Monroy, Idelfonso

    2010-01-01

    Detection of high-speed radio signals is a challenge for next generation radio-over-fibre links, requiring high bandwidth and linearity in the receiver. By using photonic downconversion in a coherent receiver, detection of high bit-rate 16-QAM signals, up to 4 Gbit/s, at a 40 GHz carrier frequency...

  2. Linewidth tolerance of digital coherent receiver using Viterbi & Viterbi RF carrier recovery for radio-over-fibre links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Larsen, Knud J.

    2009-01-01

    for phase-modulated RoF optical links (2). The RF signal processing in (2) is performed using maximum likelihood RF carrier phase estimation (2). In this paper, we investigate the performance of the proposed digital coherent receiver in (2) using feedforward Viterbi & Viterbi RF carrier recovery algorithm...

  3. Coherent Detection of Wavelength Division Multiplexed Phase-Modulated Radio-over-Fibre Signals

    DEFF Research Database (Denmark)

    Zibar, Darko; Yu, Xianbin; Peucheret, Christophe

    2008-01-01

    A WDM phase-modulated Radio-over-Fibre link using digital coherent detection is experimentally demonstrated. 3 times 50 Mb/s WDM transmission of a BPSK modulated 5 GHz RF carrier is achieved over 25 km.......A WDM phase-modulated Radio-over-Fibre link using digital coherent detection is experimentally demonstrated. 3 times 50 Mb/s WDM transmission of a BPSK modulated 5 GHz RF carrier is achieved over 25 km....

  4. Experimental demonstration of a digital maximum likelihood based feedforward carrier recovery scheme for phase-modulated radio-over-fibre links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2008-01-01

    Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission.......Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission....

  5. Digital coherent receiver employing photonic downconversion for phase modulated radio-over-fibre links

    DEFF Research Database (Denmark)

    Zibar, Darko; Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil

    2009-01-01

    A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fibre optical links. The receiver is capable of operating at frequencies exceeding the bandwidth of electrical analog-to-digital converter by using photonic...... downconversion to translate the high-frequency input RF signal to the operating frequency range of the analog-to-digital converter. First, using linear digital demodulation scheme we measure SFDR of the link at microwave frequency of 5 GHz. Thereafter, successful signal demodulation of 50 Mbit/s binary phase...... shift keying (BPSK) modulated data signal at 5 GHz RF carrier frequency is experimentally demonstrated by using an analog-to-digital converter with only 1 GHz bandwidth. We successfully demonstrate signal demodulation, using the proposed digital coherent receiver with photonic downconversion, after 40...

  6. Wavelet-Coding for Radio over Fibre

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira

    As the fifth generation of mobile communication technology is developed and implemented, worldwide solutions propose the use of much greater spectrum allocations, including the millimetre-wave frequency band. Radioover-fiber (RoF) links allow straight forward integration of the mobile front...

  7. Digital coherent receiver for subcarrier multiplexed phase modulated radio-over-fibre signals

    DEFF Research Database (Denmark)

    Zibar, Darko; Larsen, Knud J.; Tafur Monroy, Idelfonso

    2009-01-01

    Digital coherent detection of multi-channel subcarrier multiplexed optically phase-modulated radio-over-fibre signals is experimentally demonstrated. Successful detection after transmission over a 40 km long fibre link of four or five 25 Mbaud BPSK/QPSK subcarrier channels in 5 GHz bandwidth...... is demonstrated using offline digital signal processing....

  8. Digital coherent receiver for phase modulated radio-over-fibre optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Yu, Xianbin; Peucheret, Christophe

    2009-01-01

    A novel digital signal processing-based coherent receiver for phase-modulated radio-over-fiber (RoF) optical links is presented and demonstrated experimentally. Error-free demodulation of 50-Mbaud binary phase-shift keying (BPSK) and quadrature phase-shift keying data signal modulated on a 5-GHz...... radio-frequency (RF) carrier is experimentally demonstrated using the proposed digital coherent receiver. Additionally, a wavelength-division-multiplexing (WDM) phase-modulated RoF optical link is experimentally demonstrated. A 3 x50 Mb/s WDM transmission of a BPSK modulated 5-GHz RF carrier is achieved...... over 25 km for the WDM channel spacing of 12.5 and 25 GHz, respectively....

  9. Experimental 2.5 Gbit/s QPSK WDM coherent phase modulated radio-over-fibre link with digital demodulation by a K-means algorithm

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Caballero Jambrina, Antonio; Amaya Fernández, Ferney Orlando

    2009-01-01

    Highest reported bit rate of 2.5 Gbit/s for optically phase modulated radio-over-fibre link employing coherent detection is demonstrated. Demodulation of 3·2.5 Gbit/s QPSK modulated WDM channels, is achieved after 79km of transmission through deployed fiber.......Highest reported bit rate of 2.5 Gbit/s for optically phase modulated radio-over-fibre link employing coherent detection is demonstrated. Demodulation of 3·2.5 Gbit/s QPSK modulated WDM channels, is achieved after 79km of transmission through deployed fiber....

  10. Simultaneous optical carrier and radio frequency re-modulation in radio-over-fiber systems employing reflective SOA modulators

    DEFF Research Database (Denmark)

    Kassar, Carvalho; Calabretta, Nicola; Tafur Monroy, Idelfonso

    2007-01-01

    We demonstrate an innovative full-duplex radio-over-fibre transmission system employing a reflective SOA to perform simultaneous reusing of the optical carrier and data re-modulation, thus avoiding the use of local radiofrequency oscillator at the station sites.......We demonstrate an innovative full-duplex radio-over-fibre transmission system employing a reflective SOA to perform simultaneous reusing of the optical carrier and data re-modulation, thus avoiding the use of local radiofrequency oscillator at the station sites....

  11. Effect of the degree of phase-correlation of laser sources on the transmission and optical coherent detection in radio-over-fibre systems

    Science.gov (United States)

    Maldonado-Basilio, Ramón; Li, Ran; Abdul-Majid, Sawsan; Nikkhah, Hamdam; Leong, Kin-Wai; Hall, Trevor J.

    2013-01-01

    The deployment of high capacity Radio-over-Fiber (RoF) systems rely, among many aspects, on the capability to efficiently generate, transport, and detect millimeter-wave carriers modulated at high data rates. Photonic approaches based on the heterodyne beating of two free-running laser sources have been proposed as an alternative to generate multi-Gbps quadrature phase modulated signals imposed on millimeter wave carriers. Implementing photonic approaches in the down-link avoids the need for electronic generation of high frequency carriers and decreases the requirements at the base band electronics. In addition, implementing complex modulation formats overcomes some of the typical issues found in intensity modulation direct detection approaches such as non­ linearity, receiver sensitivity and dynamic range. In this work, the performance improvement of a coherent RoF system carrying 10 Gbps QPSK signals is numerically analyzed in terms of both the frequency linewidth and the degree of phase correlation between the lasers utilised at the down-link (for the optical heterodyne beating) and at the up-link (for the optical coherent detection). Relative to phase correlated lasers featuring linewidths of 5 MHz, the peak power of the 60 G Hz carrier generated at the down-link is reduced by 8 dB for un-correlated lasers. In addition, the error vector magnitude of the received signal at the up-link is improved from over 20% (for un-correlated lasers and linewidths of 5 MHz) to around 15% (for correlated lasers) at an optical received power of -30 dBm. The results obtained reinforce the idea of using coherent comb laser sources with phase correlated modes located at the Central Office. It also motivates the eventual deployment of techniques to control the degree of phase correlation between the lasers used as signal and local oscillator at the optical coherent receivers.

  12. Optical frequency tripling with improved suppression and sideband selection.

    Science.gov (United States)

    Thakur, Manoj P; Medeiros, Maria C R; Laurêncio, Paula; Mitchell, John E

    2011-12-12

    A novel optical dispersion tolerant millimetre-wave radio-over-fibre system using optical frequency tripling technique with enhanced and selectable sideband suppression is demonstrated. The implementation utilises cascaded optical modulators to achieve either an optical single sideband (OSSB) or double sideband-suppressed carrier (DSB-SC) signal with high sideband suppression. Our analysis and simulation results indicate that the achievable suppression ratio of this configuration is only limited by other system factors such as optical noise and drifting of the operational conditions. The OSSB transmission system performance is assessed experimentally by the transport of 4 WiMax channels modulating a 10 GHz optical upconverted RF carrier as well as for optical frequency doubling and tripling. The 10 GHz and tripled carrier at 30 GHz are dispersion tolerant resulting both in an average relative constellation error (RCE) of -28.7 dB after 40 km of fibre.

  13. Advanced two-way satellite frequency transfer by carrier-phase and carrier-frequency measurements

    Science.gov (United States)

    Fujieda, Miho; Gotoh, Tadahiro; Amagai, Jun

    2016-06-01

    Carrier-phase measurement is one of the ways to improve the measurement resolution of two-way satellite frequency transfer. We introduce two possible methods for carrier-phase measurement: direct carrier-phase detection identified by Two-Way Carrier-Phase (TWCP) and the use of carrier-frequency information identified by Two-Way Carrier Frequency (TWCF). We performed the former using an arbitrary waveform generator and an analog-to-digital sampler and the latter using a conventional modem. The TWCF measurement using the modem had a resolution of 10-13 and the result agreed with that obtained by GPS carrier-phase frequency transfer in a 1500 km baseline. The measurement accuracy may have been limited by the poor frequency resolution of the modem; however, the TWCF measurement was able to improve the stability of conventional two-way satellite frequency transfer. Additionally, we show that the TWCP measurement system has the potential to achieve a frequency stability of 10-17.

  14. An Estimation Method for number of carrier frequency

    Directory of Open Access Journals (Sweden)

    Xiong Peng

    2015-01-01

    Full Text Available This paper proposes a method that utilizes AR model power spectrum estimation based on Burg algorithm to estimate the number of carrier frequency in single pulse. In the modern electronic and information warfare, the pulse signal form of radar is complex and changeable, among which single pulse with multi-carrier frequencies is the most typical one, such as the frequency shift keying (FSK signal, the frequency shift keying with linear frequency (FSK-LFM hybrid modulation signal and the frequency shift keying with bi-phase shift keying (FSK-BPSK hybrid modulation signal. In view of this kind of single pulse which has multi-carrier frequencies, this paper adopts a method which transforms the complex signal into AR model, then takes power spectrum based on Burg algorithm to show the effect. Experimental results show that the estimation method still can determine the number of carrier frequencies accurately even when the signal noise ratio (SNR is very low.

  15. Carrier Density and Plasma Frequency of Aluminum Nanofilms

    Institute of Scientific and Technical Information of China (English)

    Hao DU; Jun GONG; Chao SUN; Rongfang HUANG; Lishi WEN; W.Y.Cheung; S.P.Wong

    2003-01-01

    In this work, the prerequisite and mode of electromagnetic response of Al nanofilms to electromagnetic wave field was suggested.Reflectance, transmittance in infrared region and carrier density of the films was measured. With the carrier density of the films, the dependence of their plasma frequencies on the film thickness was obtained. On the other hand, the dependence of absorptance on the frequency of electromagnetic wave field was set up by using the measured reflectance and transmittance,which provided plasma frequency-film thickness relation as well. Similarity of both plasma frequency-film thickness relations proved plasma resonance as a mode of electromagnetic response in Al nanofilms.

  16. A generalized carrier frequency offset estimator for uplink OFDMA

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; De Carvalho, Elisabeth; Prasad, Ramjee

    This paper proposes a generalized carrier frequency offset (CFO) estimator for the uplink of orthogonal frequency division multiple access (OFDMA) wireless systems. Using the maximum likelihood criterion, the estimator estimates CFOs using the phase shift between two observation windows at distance...

  17. Improved Carrier Frequency Offset Estimation in OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ming; LIU Yuan-an

    2004-01-01

    A new carrier frequency offset estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed. The proposed algorithm is an improvement of the Michele Morelli (M&M) algorithm. It also uses a training symbol which is divided into L>2 identical parts to estimate the carrier frequency offset, and the estimation range is ±L/2 the subcarrier spacing, but the performance of the proposed Maximum Likelihood (ML) algorithm is more robust and complex efficient than the M&M algorithm.

  18. An ultrawide-bandwidth single-sideband modulator for terahertz frequencies

    Science.gov (United States)

    Meijer, A. S.; Berden, G.; Arslanov, D. D.; Ozerov, M.; Jongma, R. T.; van der Zande, W. J.

    2016-11-01

    Wireless high-speed data communication using terahertz (THz) carrier frequencies is becoming reality with data rates beyond 100 Gbit s-1. Many of the mobile applications use internet access and require that THz wireless base stations are connected to a global network, such as the radio-over-fibre network. We present the realization of an ultrawide bandwidth THz optical single-sideband (OSSB) modulator for converting (free-space) THz signals to THz optical modulations with an increased spectral efficiency. THz OSSB will mitigate chromatic dispersion-induced propagation losses in optical fibres and support digital modulation schemes. We demonstrate THz OSSB for free-space radiation between 0.3 and 1.0 THz using a specially designed dichroic beamsplitter for signal and carrier, and a planar light-wave circuit with multimode interference structures. This arrangement of optical elements mimics the Hartley single-sideband modulator for electronics signals and accomplishes the required Hilbert transform without any frequency-dependent tuning element over an ultrawide THz spectrum.

  19. High carrier frequency of 21-hydroxylase deficiency in Cyprus.

    Science.gov (United States)

    Phedonos, A A P; Shammas, C; Skordis, N; Kyriakides, T C; Neocleous, V; Phylactou, L A

    2013-12-01

    Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder caused by mutations in the CYP21A2 gene. The carrier frequency of CYP21A2 mutations has been estimated to be 1:25 to 1:10 on the basis of newborn screening. The main objective of this study was to determine the carrier frequency in the Cypriot population of mutations in the CYP21A2 gene. Three hundred unrelated subjects (150 males and 150 females) from the general population of Cyprus were screened for mutations in the CYP21A2 gene and its promoter. The CYP21A2 genotype analysis identified six different mutants and revealed a carrier frequency of 9.83% with the mild p.Val281Leu being the most frequent (4.3%), followed by p.Qln318stop (2.5%), p.Pro453Ser (1.33%), p.Val304Met (0.83%), p.Pro482Ser (0.67%) and p.Met283Val (0.17%). The notable high CYP21A2 carrier frequency of the Cypriot population is one of the highest reported so far by genotype analysis. Knowledge of the mutational spectrum of CYP21A2 will enable to optimize mutation detection strategy for genetic diagnosis of 21-OHD not only in Cyprus, but also the greater Mediterranean region.

  20. Carrier Frequency Offset Compensation for an Interleaved OFDMA Uplink

    Institute of Scientific and Technical Information of China (English)

    FAN Da; CAO Zhigang

    2008-01-01

    This paper reports an investigation of the carrier frequency offset (CFO) compensation in the up-link of the orthogonal frequency division multiple access (OFDMA) system with interleaved subcarrier as-signment. The presence of CFOs between the transmitters and the uplink receiver will destroy the orthogo-nality among the different subcarriers, resulting in inter-carrier interference and multiuser interference. This paper proposes a pseudoinverse CFO compensation method based on the signal structure. The proposed method can compensate the CFOs of all users simultaneously and isolate the signals from all users at the same time. Compared with the existing CFO compensation methods, the new method provides a consider-able signal-to-noise ratio gain on the bit error rate performance and has a relatively low implementation complexity.

  1. A novel velocity estimator using multiple frequency carriers

    DEFF Research Database (Denmark)

    Zhang, Zhuo; Jakobsson, Andreas; Nikolov, Svetoslav;

    2004-01-01

    -to-noise ratio is low, and some averaging in depth is applied to improve the estimate. Further, due to velocity gradients in space and time, the spectrum may get smeared. An alternative approach is to use a pulse with multiple frequency carriers, and do some form of averaging in the frequency domain. However......Most modern ultrasound scanners use the so-called pulsed-wave Doppler technique to estimate the blood velocities. Among the narrowband-based methods, the autocorrelation estimator and the Fourier-based method are the most commonly used approaches. Due to the low level of the blood echo, the signal....... In this paper, we propose a nonlinear least squares (NLS) estimator. Typically, NLS estimators are computationally cumbersome, in general requiring the minimization of a multidimensional and often multimodal cost function. Here, by noting that the unknown velocity will result in a common known frequency...

  2. A joint recovery scheme for carrier frequency offset and carrier phase noise using extended Kalman filter

    Science.gov (United States)

    Li, Linqian; Feng, Yiqiao; Zhang, Wenbo; Cui, Nan; Xu, Hengying; Tang, Xianfeng; Xi, Lixia; Zhang, Xiaoguang

    2017-07-01

    A joint carrier recovery scheme for polarization division multiplexing (PDM) coherent optical transmission system is proposed and demonstrated, in which the extended Kalman filter (EKF) is exploited to estimate and equalize the carrier frequency offset (CFO) and carrier phase noise (CPN) simultaneously. The proposed method is implemented and verified in the PDM-QPSK system and the PDM-16QAM system with the comparisons to conventional improved Mth-power (IMP) algorithm for CFO estimation, blind phase search (BPS) algorithm or Viterbi-Viterbi (V-V) algorithm for CPN recovery. It is demonstrated that the proposed scheme shows high CFO estimation accuracy, with absolute mean estimation error below 1.5 MHz. Meanwhile, the proposed method has the CFO tolerance of [±3 GHz] for PDM-QPSK system and [±0.9 GHz] for PDM-16QAM system. Compare with IMP/BPS and IMP/V-V, the proposed scheme can enhance the linewidth symbol duration product from 3 × 10-4 (IMP/BPS) and 2 × 10-4 (IMP/V-V) to 1 × 10-3 for PDM-QPSK, and from 1 × 10-4 (IMP/BPS) to 3 × 10-4 for PDM-16QAM, respectively, at the 1 dB optical signal-to-noise ratio (OSNR) penalty. The proposed Kalman filter also shows a fast convergence with only 100 symbols and much lower computational complexity.

  3. A New Improved Variable Frequency Triangular Carrier-PWM with MOPSO Algorithm for Carrier Based PWM Techniques in Inverters

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Orfi Yegane

    2017-02-01

    Full Text Available This paper investigates multi-carrier PWM methods in multi-level inverters. Two new MCPWM methods are introduced. This study proposes a new optimized MCPWM method to improve the output voltage characteristics like THD and LOH. The proposed method is based on variable frequency with a specific range. It means each carrier wave has a determined frequency. It is calling Variable Frequency Triangular Carrier-PWM. MOPSO algorithm is used to optimize the answers. This work considers some different levels of inverters like five, seven and nine levels. The results are compared with SPWM method.

  4. Revealing Carrier-Envelope Phase through Frequency Mixing and Interference in Frequency Resolved Optical Gating

    CERN Document Server

    Snedden, Edward W; Jamison, Steven P

    2015-01-01

    We demonstrate that full temporal characterisation of few-cycle electromagnetic pulses, including retrieval of the carrier envelope phase (CEP), can be directly obtained from Frequency Resolved Optical Gating (FROG) techniques in which the interference between non-linear frequency mixing processes is resolved. We derive a framework for this scheme, defined Real Domain-FROG (ReD-FROG), as applied to the cases of interference between sum and difference frequency components and between fundamental and sum/difference frequency components. A successful numerical demonstration of ReD-FROG as applied to the case of a self-referenced measurement is provided. A proof-of-principle experiment is performed in which the CEP of a single-cycle THz pulse is accurately obtained and demonstrates the possibility for THz detection beyond the bandwidth limitations of electro-optic sampling.

  5. Performance of a novel carrier frequency offset estimation algorithm for OFDM-based WLANs

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents a novel carrier frequency offset estimation (CFO) algorithm for orthogonal frequency division multiplexing (OFDM)-based Wireless Local Area Networks (WLANs). Compared with previous approaches, this paper extends the whole frequency offset acquisition range by embedding a synthetic algorithm according to the preamble structure of WLANs symbols. The numerical results presented support the effectiveness of this algorithm by which the estimation error of the whole carrier frequency offset in the WLANs is effectively decreased.

  6. Carrier recovery techniques for semiconductor laser frequency noise for 28 Gbd DP-16QAM

    DEFF Research Database (Denmark)

    Iglesias Olmedo, Miguel; Pang, Xiaodan; Piels, Molly

    2015-01-01

    We report on the first experimental comparison of DD-PLL, two-stage feed forward, and two variations of extended Kalman filtering for tracking semiconductor laser frequency noise. We identify which carrier phase recovery technique works best depending on the carrier induced frequency noise profile....

  7. Extending the unambiguous velocity range using multiple carrier frequencies

    DEFF Research Database (Denmark)

    Zhang, Z.; Jakobsson, A.; Nikolov, Svetoslav;

    2005-01-01

    Typically, velocity estimators based on the estimation of the Doppler shift will suffer from a limited unambiguous velocity range. Proposed are two novel multiple carrier based velocity estimators extending the velocity range above the Nyquist velocity limit. Numerical simulations indicate...

  8. 47 CFR 73.1545 - Carrier frequency departure tolerances.

    Science.gov (United States)

    2010-10-01

    ... carrier offset, including those stations licensed with a maximum effective radiated power and/or antenna... offset. See Memorandum Opinion and Order on Reconsideration, In the Matter of Establishment of a Class...

  9. All-digital Carrier Frequency Tracking Method in LEO DS/SS Communication

    Institute of Scientific and Technical Information of China (English)

    XING Ke-fei; YANG Jun; ZHANG Chuan-sheng; WANG Yue-ke

    2006-01-01

    An efficient method to track the carrier frequency which is recommended to use in low earth orbit(LEO) direct-sequence spread-spectrum(DS/SS) communication system is given. The carrier frequency drifts quicker in LEO DS/SS communication system, its tracking problem becomes much more important especially in digital receiver with the limits of physical shape and power. Under the condition of coarse carrier frequency synchronization, a digital tracking method based on least square method(LSM) is proved to be a quick, simple and efficient method. Numerical results and charts are given.

  10. System Frequency as Information Carrier in AC Power Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Heussen, Kai; You, Shi

    2015-01-01

    Power generators contain control systems able to regulate system frequency, but the frequency setpoint values are only rarely modified from nominal values. This paper describes design considerations for a communication system from generators to frequency sensitive distributed energy resourc es (FS...... to carry information: First, a protocol for dispatching blocks of FS- DER that is suitable for systems restricted to relatively slow rates of change of frequency (ROCOF). Second, for systems that allow higher ROCOF values, the feasibility of using power generation resources as a power line communication......-DER) using changes to frequency setpoint values of genera- tors. Signaling discrete system states by generating off-nominal system frequency values can be used as a novel narrowband unidirectional broadcast communications channel. This paper describes two protocols for utilizing off-nominal frequencies...

  11. Tilted-reference-beam lateral shearing interferometer utilizing carrier-frequency photography.

    Science.gov (United States)

    Hong, Y M

    1975-03-01

    Double-exposure carrier-frequency photography where the grating is rotated between exposures is used for observing phase objects. The resulting interferogram is similar to those obtained from interferometers using a tilted reference beam. Positive and negative gradients of the phase variation can be distinguished. Furthermore, it is shown that the image of a grating in carrier-frequency photography can be achieved by using an image-forming lens or by using the self-imaging property of the grating.

  12. Power dependence of terahertz carrier frequency in a plasma-based two-color generation process

    Science.gov (United States)

    Zhao, Ji; Zhang, Liang-Liang; Luo, Yi-Man; Wu, Tong; Zhang, Cun-Lin; Zhao, Yue-Jin

    2014-12-01

    We conduct a frequency spectrum experiment to investigate terahertz (THz) emissions from laser-induced air plasma under different laser incident powers. The frequency spectra are measured using both air-biased-coherent detection and a Michelson interferometer. The red-shift of the THz pulse carrier frequency is observed as a response to increased pump power. These phenomena are related to plasma collisions and can be explained by the plasma collision model. Based on these findings, it is apparent that the tuning of the THz carrier frequency can be achieved through regulation of the pump beam.

  13. Timing, carrier frequency and phase recovery for OFDM and Nyquist signals using a mean modulus algorithm.

    Science.gov (United States)

    Schmogrow, R; Nebendahl, B; Josten, A; Schindler, P C; Koos, C; Freude, W; Leuthold, J

    2014-04-21

    Efficient algorithms for timing, carrier frequency and phase recovery of Nyquist and OFDM signals are introduced and experimentally verified. The algorithms exploit the statistical properties of the received signals to efficiently derive the optimum sampling time, the carrier frequency offset, and the carrier phase. Among the proposed methods, the mean modulus algorithm (MMA) shows a very robust performance at reduced computational complexity. This is especially important for optical communications where data rates can exceed 100 Gbit/s per wavelength. All proposed algorithms are verified by simulations and by experiments using optical M-ary QAM Nyquist and OFDM signals with data rates up to 84 Gbit/s.

  14. Effects of carrier frequency of interferential current on pressure pain threshold and sensory comfort in humans.

    Science.gov (United States)

    Venancio, Roberta Ceila; Pelegrini, Stella; Gomes, Daiane Queiroz; Nakano, Eduardo Yoshio; Liebano, Richard Eloin

    2013-01-01

    To assess the effect of carrier frequency of interferential current (IFC) on pressure pain threshold (PPT) and sensory comfort in healthy subjects. A double-blind randomized trial. University research laboratory. Healthy subjects (N=150). Application of the IFC for 20 minutes and measures of PPT collected in the regions of the nondominant hand and forearm. We measured PPT and comfort at frequencies of 1kHz, 2kHz, 4kHz, 8kHz, and 10kHz. There was a significant increase in PPT in the 1-kHz group when compared with the 8-kHz and 10-kHz groups. There was a greater discomfort in the 1-kHz and 2-kHz groups. IFC with a carrier frequency of 1kHz promotes a higher hypoalgesic response during and after stimulation than IFC with carrier frequencies of 8kHz and 10kHz. Carrier frequencies of 1kHz and 2kHz are perceived as more uncomfortable than carrier frequencies of 4kHz, 8kHz, and 10kHz. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  15. PROPAGATOR BASED CLOSED-FORM BLIND CARRIER FREQUENCY OFFSET ESTIMATION FOR OFDM SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Li Jun; Liao Guisheng; Wu Yuntao

    2006-01-01

    Most of the blind Orthogonal Frequency Division Multiplexing (OFDM) Carrier Frequency Offeet (CFO) estimators necessitate large number of samples to ensure the estimation accuracy. However, the number of samples can not be selected too large because of the carrier offset drift. In this letter, a new closed form algorithm for blind OFDM CFO estimation in frequency-selective channel is proposed. This method utilizes the propagator obtained from data matrix and the diagonal loading technique, thus it has better performance even only using one or two OFDM blocks. Furthermore, the range of the CFO estimation which can be handled is overall transmission spectral. Simulation results confirm its effectiveness.

  16. CARRIER FREQUENCY OFFSET ESTIMATION FOR INTERLEAVED OFDMA UPLINK BASED ON SUBSPACE PROCESSING

    Institute of Scientific and Technical Information of China (English)

    Fan Da; Cao Zhigang

    2007-01-01

    This paper investigates Carrier Frequency Offset (CFO), estimation in the uplink of the Orthogonal Frequency-Division Multiple Access (OFDMA) systems with the interleaved subcarrier assignment. CFOs between the transmitters and the uplink receiver will destroy orthogonality among different subcarriers, hence resulting in inter-carrier interference and multiuser interference. A two-stage frequency offset estimation algorithm based on subspace processing is proposed. The main advantage of the proposed method is that it can obtain the CFOs of all users simultaneously using only one OFDMA block. Compared with the previously known methods, it not only has a relatively low implementation complexity but is also suitable for random subchannel assignment.

  17. Refraction effects on the Galileo probe telemetry carrier frequency

    Science.gov (United States)

    Atkinson, D. H.; Spilker, T. R.

    1991-01-01

    As the Galileo probe relay radio link (RRL) signal propagates outward through the Jovian atmosphere, the atmosphere will manifest itself in two ways. First, the geometric path length of the signal is increased, resulting in a small change of the RRL signal departure angle from the proble (transmitter). Secondly, the velocity of the signal is decreased. For a spherical, static atmosphere with a known profile of refractivity versus altitude the effects of refraction on the RRL frequency can be found using a variation of standard ray-tracing techniques, whereby the ray departure angle is found by an iterative process. From the dispersive characteristics of a mixture of hydrogen and helium with trace amounts of methane and ammonia a simple model of the Jovian atmosphere is constructed assuming spherical symmetry and uniform mixing. The contribution to the RRL Doppler frequency arising from refraction is calculated, and its effect on the Doppler wind measurements is discussed.

  18. Stabilized fiber-optic Mach-Zehnder interferometer for carrier-frequency rejection

    CERN Document Server

    Cooper, Nathan; Bateman, James; Dunning, Alexander; Freegarde, Tim

    2013-01-01

    We have demonstrated stabilization of a fiber-optic Mach-Zehnder interferometer, with a centimeter-scale path difference, to the transmission minimum for the carrier wave of a frequency-modulated laser beam. A time-averaged extinction of 32 dB, limited by the bandwidth of the feedback, was maintained over several hours. The interferometer was used to remove the carrier wave from a 780 nm laser beam that had been phase modulated at 2.7 GHz.

  19. Frequency Dependent Harmonic Powers in a Modified Uni-Traveling Carrier (MUTC) Photodetector

    Science.gov (United States)

    2017-01-27

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5651--17-9712 Frequency Dependent Harmonic Powers in a Modified Uni-Traveling Carrier...TELEPHONE NUMBER (include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Frequency Dependent Harmonic Powers in a...N. Hutchinson (202) 767-9549 Fiber optics Analog photonics We use a drift-diffusion model to study frequency dependent harmonic powers in a

  20. Carrier suppression in quadruple frequency modulation by cascaded optical external modulators for millimeter-wave generation

    Institute of Scientific and Technical Information of China (English)

    Xue Feng; Wei Zhang; Xiaoming Liu

    2009-01-01

    The optical carrier suppression in optical quadruple frequency modulation by cascaded external modulators is investigated theoretically and experimentally. Theoretical analysis demonstrates that the optical carrier suppression ratio is related with not only the initial phase difference of electrical signals applied on the two modulators, but also the optical phase shift between the two modulators. The maximum suppression ratio can be achieved when the total phase difference is equal to nπ+π/2(n=1,2…),which is verified by experiments. By properly controlling the total phase shift, 40-GHz millimeter-wave is generated by using a 10-GHz radio frequency (RF) source and the modulators.

  1. An Experiment for Generating the 14-Tone Stable Carriers Using Recirculating Frequency Shifter

    Institute of Scientific and Technical Information of China (English)

    TIAN Feng; ZHANG Xiao-Guang; LI Jian-Ping; XI Li-Xia

    2010-01-01

    @@ In experiment,the generation of 14-tone stable carriers with recirculating frequency shifter is realized.Some factors that impact the performance of the carrier generation are discussed.It is experimentally found that the balance and the insertion loss of the inphase/quadrature (l/Q,) modulator,the accurate π /2 phase difference and equal power level of two rf signals which are applied to the two ports of the I/Q modulator,the gain of the optical amplifier,the bandwidth and sharp window spectrum of the tunable filter and the stability of the optical signals' states of polarization fed into I/Q modulator,play important roles in the generation of a stable multi-tone carrier source.By employing appropriate techniques we obtain 14-tone stable carriers in the experiment.

  2. Single Carrier Architecture for High Data Rate Wireless PAN Communications System

    CERN Document Server

    Rakotondrainibe, Lahatra; Zaharia, Gheorghe; Grunfelder, Guy; Zein, Ghaïs El

    2010-01-01

    A 60 GHz wireless Gigabit Ethernet (G.E.) communication system is developed at IETR. As the 60 GHz radio link operates only in a single-room configuration, an additional Radio over Fibre (RoF) link is used to ensure the communications in all the rooms of a residential environment. The realized system covers 2 GHz bandwidth. Due to the hardware constraints, a symbol rate at 875 Mbps is attained using simple single carrier architecture. In the baseband (BB) processing block, an original byte/frame synchronization process is designed to provide a smaller value of the preamble missing detection and false alarm probabilities. Bit error rate (BER) measurements have been realized in a large gym for line-of-sight (LOS) conditions. A Tx-Rx distance greater than 30 meters was attained with low BER using high gain antennas and forward error correction RS (255, 239) coding.

  3. Time synchronization and carrier frequency control of CAPS navigation signals generated on the ground

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The Chinese Area Positioning System (CAPS) works without atomic clocks on the satellite, and the CAPS navigation signals transmitted on the ground may achieve the same effect as that with high-performance atomic clocks on the satellite. The primary means of achieving that effect is through the time synchronization and carrier frequency control of the CAPS navigation signals generated on the ground. In this paper the synchronization requirements of different time signals are analyzed by the formation of navigation signals, and the theories and methods of the time synchronization of the CAPS navigation signals generated on the ground are also introduced. According to the conditions of the high-precision satellite velocitymeasurement signal source, the carrier frequency and its chains of the navigation signals are constructed. CAPS velocity measurement is realized by the expected deviation of real time control to the carrier frequency, and the precision degree of this method is also analyzed. The experimental results show that the time synchronization precision of CAPS generating signals is about 0.3 ns and the precision of the velocity measurement signal source is about 4 cm/s. This proves that the theories and methods of the generating time synchronization and carrier frequency control are workable.

  4. Time synchronization and carrier frequency control of CAPS navigation signals generated on the ground

    Institute of Scientific and Technical Information of China (English)

    WU HaiTao; BIAN YuJing; LU XiaoChun; LI XiaoHui; WANG DanNi

    2009-01-01

    The Chinese Area Positioning System (CAPS) works without atomic clocks on the satellite,and the CAPS navigation signals transmitted on the ground may achieve the same effect as that with high-performance atomic clocks on the satellite.The primary means of achieving that effect is through the time synchronization and carrier frequency control of the CAPS navigation signals generated on the ground.In this paper the synchronization requirements of different time signals are analyzed by the formation of navigation signals,and the theories and methods of the time synchronization of the CAPS navigation signals generated on the ground are also introduced.According to the conditions of the high-precision satellite velocity-measurement signal source,the carrier frequency and its chains of the navigation signals are constructed.CAPS velocity measurement is realized by the expected deviation of real time control to the carrier frequency,end the precision degree of this method is also analyzed.The experimental results show that the time synchronization precision of CAPS generating signals is about 0.3 ns and the precision of the velocity measurement signal source is about 4 cm/s.This proves that the theories and methods of the generating time synchronization and carrier frequency control are workable.

  5. Carrier Frequency Offset Estimation and I/Q Imbalance Compensation for OFDM Systems

    Directory of Open Access Journals (Sweden)

    M. Omair Ahmad

    2007-01-01

    Full Text Available Two types of radio-frequency front-end imperfections, that is, carrier frequency offset and the inphase/quadrature (I/Q imbalance are considered for orthogonal frequency division multiplexing (OFDM communication systems. A preamble-assisted carrier frequency estimator is proposed along with an I/Q imbalance compensation scheme. The new frequency estimator reveals the relationship between the inphase and the quadrature components of the received preamble and extracts the frequency offset from the phase shift caused by the frequency offset and the cross-talk interference due to the I/Q imbalance. The proposed frequency estimation algorithm is fast, efficient, and robust to I/Q imbalance. An I/Q imbalance estimation/compensation algorithm is also presented by solving a least-square problem formulated using the same preamble as employed for the frequency offset estimation. The computational complexity of the I/Q estimation scheme is further reduced by using part of the short symbols with a little sacrifice in the estimation accuracy. Computer simulation and comparison with some of the existing algorithms are conducted, showing the effectiveness of the proposed method.

  6. Carrier frequency of GJB2 and GALT mutations associated with sensorineural hearing loss and galactosemia in the Russian population

    OpenAIRE

    Abramov D.D.; Belousova M.V.; Kadochnikova V.V.; Ragimov A.A.; Trofimov D.Yu.

    2016-01-01

    This article continues a series of works estimating carrier frequencies of mutations associated with the development of common monogenic disorders in the Russian population. The study aimed to establish the frequency of GJB2 and GALT mutations in first-time blood donors. Genotyping of 1000 first-time blood donors who identify themselves as Russians and permanently reside in the Russian Federation detected 37 carriers of GJB2 mutations associated with sensorineural hearing loss (carrier freque...

  7. Multi-User Interference Cancellation Scheme(s) for Muliple Carrier Frequency Offset Compensation in Uplink OFDMA

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; Carvalho, Elisabeth De; Prasad, Ramjee

    2006-01-01

    We consider the uplink of an Orthogonal Frequency Division Multiple Access (OFDMA)-based system, where each Mobile Station (MS) experiences a different Carrier Frequency Offset (CFO). Uncorrected CFO destroy the orthogonality among subcarriers, which could cause severe Inter-Carrier Interference...

  8. Positioning Precision Analysis of GNSS Multi-frequency Carrier Phase Combinations

    Institute of Scientific and Technical Information of China (English)

    WU Yue; PAN Yong; FAN Yimin; WANG Xiaojun

    2007-01-01

    GPS positioning precision is affected by various error sources, and traditional combinations of GPS carrier phase observations have their own limitations such as the wide-lane, the narrow-lane and the ionospheric-free combinations. To obtain the optimal positioning precision, a new linear combination method is addressed through the variance-covariance (VCV)of the GPS multi-frequency carrier phase combination equations, and the impact of the positioning precision is analyzed with the changing of the observation errors deduced by the law of error propagation. For the high precision positioning with only one carrier phase combination, the optimal combination method is deduced and further validated by an example of a baseline resolution with 60 km length. The result indicates that this method is the simplest, and the positioning precision is the best. Therefore, it is useful for long baseline quick positioning for different precision requirements in various distances.

  9. Tay Sachs disease in Australia: reduced disease incidence despite stable carrier frequency in Australian Jews.

    Science.gov (United States)

    Lew, Raelia M; Proos, Anne L; Burnett, Leslie; Delatycki, Martin; Bankier, Agnes; Fietz, Michael J

    2012-12-10

    To evaluate the outcomes of preconception screening of Jewish Australians for Tay Sachs disease (TSD) carrier status on Jewish TSD-affected births. Epidemiological observational study involving a complete retrospective audit of infantile and intermediate TSD cases diagnosed in Sydney and Melbourne between 1 January 1995 and 31 December 2011 (Royal Children's Hospital Melbourne; Pacific Laboratory Medicine Services, Pathology North, NSW Health Pathology, Sydney; Victorian Clinical Genetics Services, Melbourne; and SA Pathology, Adelaide), and carrier frequency among Jewish high school students attending schools participating in TSD screening programs over the same period. Jewish TSD carrier frequency; and expected versus observed Jewish TSD-affected births. The 2006 Census indicated that most of the total 88,826 Jewish Australians live in Melbourne (46%) and Sydney (40%). The 7,756 Jewish high school students screened for TSD in Sydney and Melbourne during the study period had a carrier frequency of one in 31 (3.26%; 95% CI, 2.89%-3.68%).The estimated expected number of TSD-affected births in Melbourne and Sydney in 1995-2011 was 4.1 for Jewish births and 7.4 for other births (a ratio of Jewish to non-Jewish births of 1:2). The actual number was 12 (four in Sydney and eight in Melbourne), of which two were Jewish (a ratio of Jewish to non-Jewish births of 1:5). This finding of fewer than expected Jewish TSD cases coincided with a period during which screening programs were operating. There have been no Jewish TSD-affected children born to parents who were screened previously. Community education, appreciation of autosomal recessive inheritance and genetic carrier screening before pregnancy are the likely factors in our finding of fewer than expected Jewish babies with TSD. Ongoing outcome monitoring must continue.

  10. Acousto-optic pulse picking scheme with carrier-frequency-to-pulse-repetition-rate synchronization.

    Science.gov (United States)

    de Vries, Oliver; Saule, Tobias; Plötner, Marco; Lücking, Fabian; Eidam, Tino; Hoffmann, Armin; Klenke, Arno; Hädrich, Steffen; Limpert, Jens; Holzberger, Simon; Schreiber, Thomas; Eberhardt, Ramona; Pupeza, Ioachim; Tünnermann, Andreas

    2015-07-27

    We introduce and experimentally validate a pulse picking technique based on a travelling-wave-type acousto-optic modulator (AOM) having the AOM carrier frequency synchronized to the repetition rate of the original pulse train. As a consequence, the phase noise characteristic of the original pulse train is largely preserved, rendering this technique suitable for applications requiring carrier-envelope phase stabilization. In a proof-of-principle experiment, the 1030-nm spectral part of an 74-MHz, carrier-envelope phase stable Ti:sapphire oscillator is amplified and reduced in pulse repetition frequency by a factor of two, maintaining an unprecedentedly low carrier-envelope phase noise spectral density of below 68 mrad. Furthermore, a comparative analysis reveals that the pulse-picking-induced additional amplitude noise is minimized, when the AOM is operated under synchronicity. The proposed scheme is particularly suitable when the down-picked repetition rate is still in the multi-MHz-range, where Pockels cells cannot be applied due to piezoelectric ringing.

  11. Frequency of thalassemia carrier and Hb variant and the quality of stored donor blood

    Directory of Open Access Journals (Sweden)

    Eva A. Maharani

    2015-01-01

    Full Text Available Background: This study was aimed to determine the frequency of thalassemia and Hb variant in blood donor. In addition, we also wanted to know the quality of blood from the donor up to seven days of storage, by calculating percentage of hemolysis in vitro.Methods: This cross-sectional study was conducted on 138 blood donor specimens at Red Cross Blood Centre Unit in Jakarta. All specimens were tested for thalassemia and Hb variant by complete blood count (CBC and Hb analysis with HPLC method and DNA analysis for the detection of α thalassemia carrier. To analyze the quality of stored blood, the calculation of hemolytic rate of red blood cells (RBCs on whole blood (WB was compared between the first and seventh days of storage.Results: Out of the 138 specimens, 5 samples (3.6% were diagnosed for α thalassemia carrier in which, one of them is co-inherited with ovalositosis hereditary (Southeast Asian Ovalositosis/SAO, 3 samples (2.2% for β thalassemia carrier, and 3 samples (2.2% for Hb E. Meanwhile, the hemolytic rates of RBCs on WB in first day and seven day of storage were below one percent.Conclusion: The frequency of thalassemia carrier and Hb variants in blood donors at Red Cross Blood Centre Unit in Jakarta was 8%. The quality of stored blood until seven day of storage was quite good.

  12. ESTIMATION OF CARRIER FREQUENCY OFFSETS FOR MIMO SYSTEMS WITH DISTRIBUTED TRANSMIT ANTENNAS

    Institute of Scientific and Technical Information of China (English)

    Deng Kai; Tang Youxi; Lei Xia; Li Shaoqian

    2007-01-01

    The problem of estimating the carrier frequency offsets in Multiple-Input Multiple-Output (MIMO) systems with distributed transmit antennas is addressed. It is supposed that the transmit antennas are distributed while the receive antennas are still centralized, and the general case where both the time delays and the frequency offsets are possibly different for each transmit antenna is considered. The channel is supposed to be frequency flat, and the macroscopic fading is also taken into consideration. A carrier frequency offset estimator based on Maximum Likelihood (ML) is proposed,which can separately estimate the frequency offset for each transmit antenna and exploit the spatial diversity. The Cramer-Rao Bound (CRB) for synchronous MIMO (i.e., the time delays for each transmit antenna are all equal) is also derived. Simulation results are given to illustrate the performance of the estimator and compare it with the CRB. It is shown that the estimator can provide satisfactory frequency offset estimates and its performance is close to the CRB for the Signal-to-Noise Ratio (SNR) below 20dB.

  13. Combined Transmission of Baseband NRZ-DQPSK and Phase Modulated Radio-over-Fibre

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Yu, Xianbin; Tafur Monroy, Idelfonso

    2008-01-01

    21.4 Gbit/s baseband DQPSK and 1.25 Gbit/s phase modulated RoF was transmitted over 80 km SSMF using polarization multiplexing.......21.4 Gbit/s baseband DQPSK and 1.25 Gbit/s phase modulated RoF was transmitted over 80 km SSMF using polarization multiplexing....

  14. Carrier frequency offset estimation for OFDM systems with time-varying DC Offset

    Science.gov (United States)

    Liu, Tao; Li, Hanzhang

    2012-12-01

    Orthogonal frequency division multiplexing (OFDM) systems with direct-conversion architecture suffer from both carrier frequency offset (CFO) and dc offset (DCO). In this paper, we study CFO estimation problem for OFDM systems with time-varying DCO (TV-DCO) caused by gain mode switch of low noise amplifier (LNA). Based on linear approximation of TV-DCO, a blind algorithm is proposed for CFO estimation by means of DCO compensation and power leakage minimization. Performance of the proposed algorithm is demonstrated by simulations.

  15. Blind Carrier Frequency Offset Estimation via Power Spectrum Analysis in MIMO OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    WU Lu; ZHANG Xianda

    2009-01-01

    As a generalization of orthogonal frequency-division multiplexing (OFDM) systems,multi-input multi-output (MIMO) OFDM systems are very sensitive to carrier frequency offset (CFO).This paper proposes a blind CFO estimation method based on power spectrum analysis,which has high bandwidth efficiency and is much less complex.This method can be used to estimate the residual CFO,which is less than half of the subcarrier spacing.The method uses a cosine cost function to get a closed-form CFO estimate.Simulation results illustrate that the method is effective for MIMO OFDM systems.

  16. Improvement and Analysis of Carrier-Interferometry Orthogonal Frequency Division Multiplexing System

    Institute of Scientific and Technical Information of China (English)

    HE Jian-hui; QUAN Zi-yi; MEN Ai-dong

    2005-01-01

    This paper proposes to use Fast Fourier Transform (FFT)/Inverse Fast Fourier Transform (IFFT), instead of vector-matrix multiplication, to implement the spreading/despreading in Carrier-Interferometry Orthogonal Frequency Division Multiplexing (CI/OFDM) and Pseudo-Orthogonal Carrier-Interferometry OFDM (PO-CI/OFDM). That can improve the signal processing efficiency of CI/OFDM and PO-CI/OFDM systems by about 2N/log2N and 2N/(1+log2N) times respectively and dose not make any difference to the system function and performance. Moreover, the efficiency benefits will increase with the increase of the number of sub-carriers. In addition to that, we point out that the transmitter of CI/OFDM is actually technically equivalent to that of a single-carrier system with cyclic-prefix and the receiver of CI/OFDM is a typical OFDM receiver with CI despreading. Hence the low Peak-to-Average Power Ratio (PAPR) property and high anti-fading performance of CI/OFDM system can be well explained.

  17. An analytical study on the carrier-phase linear combinations for triple-frequency GNSS

    Science.gov (United States)

    Li, Jinlong; Yang, Yuanxi; He, Haibo; Guo, Hairong

    2016-08-01

    The linear combinations of multi-frequency carrier-phase measurements for Global Navigation Satellite System (GNSS) are greatly beneficial to improving the performance of ambiguity resolution (AR), cycle slip correction as well as precise positioning. In this contribution, the existing definitions of the carrier-phase linear combination are reviewed and the integer property of the resulting ambiguity of the phase linear combinations is examined. The general analytical method for solving the optimal integer linear combinations for all triple-frequency GNSS is presented. Three refined triple-frequency integer combinations solely determined by the frequency values are introduced, which are the ionosphere-free (IF) combination that the Sum of its integer coefficients equal to 0 (IFS0), the geometry-free (GF) combination that the Sum of its integer coefficients equal to 0 (GFS0) and the geometry-free and ionosphere-free (GFIF) combination. Besides, the optimal GF, IF, extra-wide lane and ionosphere-reduced integer combinations for GPS and BDS are solved exhaustively by the presented method. Their potential applications in cycle slip detection, AR as well as precise positioning are discussed. At last, a more straightforward GF and IF AR scheme than the existing method is presented based on the GFIF integer combination.

  18. An analytical study on the carrier-phase linear combinations for triple-frequency GNSS

    Science.gov (United States)

    Li, Jinlong; Yang, Yuanxi; He, Haibo; Guo, Hairong

    2017-02-01

    The linear combinations of multi-frequency carrier-phase measurements for Global Navigation Satellite System (GNSS) are greatly beneficial to improving the performance of ambiguity resolution (AR), cycle slip correction as well as precise positioning. In this contribution, the existing definitions of the carrier-phase linear combination are reviewed and the integer property of the resulting ambiguity of the phase linear combinations is examined. The general analytical method for solving the optimal integer linear combinations for all triple-frequency GNSS is presented. Three refined triple-frequency integer combinations solely determined by the frequency values are introduced, which are the ionosphere-free (IF) combination that the Sum of its integer coefficients equal to 0 (IFS0), the geometry-free (GF) combination that the Sum of its integer coefficients equal to 0 (GFS0) and the geometry-free and ionosphere-free (GFIF) combination. Besides, the optimal GF, IF, extra-wide lane and ionosphere-reduced integer combinations for GPS and BDS are solved exhaustively by the presented method. Their potential applications in cycle slip detection, AR as well as precise positioning are discussed. At last, a more straightforward GF and IF AR scheme than the existing method is presented based on the GFIF integer combination.

  19. Carrier-phase Two-Way Satellite Frequency Transfer over a Very Long Baseline

    CERN Document Server

    Fujieda, M; Gotoh, T; Becker, J; Aida, M; Bauch, A

    2014-01-01

    In this paper we report that carrier-phase two-way satellite time and frequency transfer (TWSTFT) was successfully demonstrated over a very long baseline of 9,000 km, established between the National Institute of Information and Communications Technology (NICT) and the Physikalisch-Technische Bundesanstalt (PTB). We verified that the carrier-phase TWSTFT (TWCP) result agreed with those obtained by conventional TWSTFT and GPS carrier-phase (GPSCP) techniques. Moreover, a much improved short-term instability for frequency transfer of $2\\times10^{-13}$ at 1 s was achieved, which is at the same level as previously confirmed over a shorter baseline within Japan. The precision achieved was so high that the effects of ionospheric delay became significant which are ignored in conventional TWSTFT even over a long link. We compensated for these effects using ionospheric delays computed from regional vertical total electron content maps. The agreement between the TWCP and GPSCP results was improved because of this compe...

  20. Performance evaluation for PCC-OFDM systems impaired by carrier frequency offset over AWGN channels

    Institute of Scientific and Technical Information of China (English)

    ZHOU Peng; ZHAO ChunMing; SHI ZhiHua; GONG XiaoQun

    2008-01-01

    Orthogonal frequency division multiplexing (OFDM) is sensitive to carrier fre- quency offset (CFO), which destroys the orthogonality and causes inter-carrier interference (ICI). ICI self-cancellation schemes based on polynomial cancellation coding (PCC-OFDM) can evidently reduce the sensitivity to CFO. In this paper, we analyze the performance of PCC-OFDM systems impaired by CFO over additive white gaussian noise (AWGN) channels. Two criteria are used to evaluate the effect of CFO on performance degradations. Firstly, the closed-form expressions of the average carrier-to-interference power ratio (CIR) and the statistical average ICI power, both of which reflect the desired power loss, are presented. Simulation and analytical results show that the theoretlcel expressions depend crucially on the normalized frequency offset and are hardly relevant to the number of subcarriers. Secondly, by exploiting the properties of the Beaulieu series, the effect of CFO on symbol error rate (SER) and bit error rate (BER) performance for PCC-OFDM sys- tems are exactly expressed as the sum of an infinite series in terms of the charac- teristic function (CHF) of ICI. We consider the systems modulated with binary phase shift keying (BPSK), quadrature PSK (QPSK), 8-ary PSK (8-PSK), and 16-ary quadrature amplitude modulation (16-QAM), and all above modulation schemes are mapped with Gray codes for the evaluations of BER.

  1. On the Estimation of Carrier Frequency Offset and DC Offset for OFDM Systems

    Science.gov (United States)

    Lin, Hai; Nakao, Takeshi; Lu, Weiming; Yamashita, Katsumi

    In an orthogonal frequency division multiplexing (OFDM) receiver with direct-conversion architecture, carrier frequency offset (CFO) and direct-current offset (DCO), which cause severe performance degradation, need to be estimated and compensated. Recently, by investigating the subspace of OFDM signal after coarse DCO cancellation using timedomain average, we have proposed a nullspace-based estimator (NSE), for blind CFO and DCO estimation. In this paper, based on an analysis of the cost function of the NSE, we propose a common nullspace based estimator (CNSE). It is shown that by matching the frequency occupation of the received OFDM signal with CFO and DCO, the CNSE can achieve the full performance potential of the NSE. Also, the performance analysis reveals that the CNSE can asymptotically approach the Cramer-Rao bound (CRB) of OFDM CFO estimation in the presence of DCO. Finally the analysis results are confirmed by simulations.

  2. Detection of Underwater Carrier-Free Pulse based on Time-Frequency Analysis

    Directory of Open Access Journals (Sweden)

    Yunlu Ni

    2013-01-01

    Full Text Available Carrier-free short pulse widely employed in UWB radar is brought into high-resolution sonar system, which has unique advantages: attaining more target information, restraining fluctuation of reverberation envelop efficiently in short-range detection and achieving accurate estimation. In essence such pulse is transiently short in time domain and wide in frequency domain, and as such it is difficult to separate signal to noise based on Fourier Transform spectrum. So as to seek for detection methods of short pulse, minor differences of energy distribution of time-frequency characteristics are presented on three time-frequency methods such as Short Time Fourier Transform, Wavelet Transform and Hilbert-Huang Transform. With these results, a tri-channel detector is established for such underwater short pulse in noise environment, which is generally suitable not only for detection module of underwater sonar system but also that of radar system.

  3. Supercontinuum generation and carrier envelope offset frequency measurement in a tapered single-mode fiber

    CERN Document Server

    Zhang, Long; Zhao, Yanying; Hou, Lei; Yu, Zijiao; Wei, Zhiyi

    2014-01-01

    We report supercontinuum generation by launching femtosecond Yb fiber laser pulses into a tapered single-mode fiber of 3 um core diameter. A spectrum of more than one octave, from 550 to 1400 nm, has been obtained with an output power of 1.3 W at a repetition rate of 250 MHz, corresponding to a coupling efficiency of up to 60%. By using a typical f-2f interferometer, the carrier envelope offset frequency was measured and found to have a signal-to-noise ratio of nearly 30 dB.

  4. Digital pilot aided carrier frequency offset estimation for coherent optical transmission systems.

    Science.gov (United States)

    Zhao, Donghe; Xi, Lixia; Tang, Xianfeng; Zhang, Wenbo; Qiao, Yaojun; Zhang, Xiaoguang

    2015-09-21

    We present a digital pilot aided carrier frequency offset estimation (FOE) method for coherent optical transmission systems. Unlike the conventional pilot tone insertion scheme, the pilot of the proposed method is generated in a digital manner and can serve as a good FOE indicator. Aided by this kind of digital pilot, the FOE is implemented by determining the location of the digital pilot in the spectrum. Theoretical analysis and numerical simulations show that the proposed method has the advantages in wide range, high accuracy, modulation formats independent, no need to remove the modulation, and high tolerance to the residual chromatic dispersion (CD) and polarization mode dispersion (PMD).

  5. Joint maximum likelihood estimation of carrier and sampling frequency offsets for OFDM systems

    CERN Document Server

    Kim, Y H

    2010-01-01

    In orthogonal-frequency division multiplexing (OFDM) systems, carrier and sampling frequency offsets (CFO and SFO, respectively) can destroy the orthogonality of the subcarriers and degrade system performance. In the literature, Nguyen-Le, Le-Ngoc, and Ko proposed a simple maximum-likelihood (ML) scheme using two long training symbols for estimating the initial CFO and SFO of a recursive least-squares (RLS) estimation scheme. However, the results of Nguyen-Le's ML estimation show poor performance relative to the Cramer-Rao bound (CRB). In this paper, we extend Moose's CFO estimation algorithm to joint ML estimation of CFO and SFO using two long training symbols. In particular, we derive CRBs for the mean square errors (MSEs) of CFO and SFO estimation. Simulation results show that the proposed ML scheme provides better performance than Nguyen-Le's ML scheme.

  6. Blind estimation of carrier frequency offset, I/Q imbalance and DC offset for OFDM systems

    Science.gov (United States)

    Liu, Tao; Li, Hanzhang

    2012-12-01

    Sensitivity to carrier frequency offset (CFO) is one of the biggest drawbacks of orthogonal frequency division multiplexing (OFDM) system. A lot of CFO estimation algorithms had been studied for compensation of CFO in OFDM system. However, with the adoption of direct-conversion architecture (DCA), which introduces additional impairments such as dc offset (DCO) and in-phase/quadrature (I/Q) imbalance in OFDM system, the established CFO estimation algorithms suffer from performance degradation. In our previous study, we developed a blind CFO, I/Q imbalance and DCO estimation algorithm for OFDM systems with DCA. In this article, we propose an alternative algorithm with reduced computation complexity and better accuracy. Performance of the proposed algorithm is demonstrated by simulations.

  7. Single carrier frequency domain equalization and diversity combining for cooperative systems

    Institute of Scientific and Technical Information of China (English)

    Xiong Haitao; Xu Jing; Wang Ping

    2009-01-01

    A low-complexity single carrier frequency-domain equalizer (SC/FDE) and diversity combining method for cooperative systems with demodulate-and-forward relaying over frequency-selective channels is proposed. At the relay nodes, linear SC/FDE is adopted and normalized correlation coefficient is introduced to derive an equivalent source-to-relay-destination (S-R-D) channel that is highlighted in this study. At the destination, a joint SC/FDE and diversity combining receiver is proposed by utilizing the equivalent S-R-D channel. Simulation results demonstrate the superiority of the proposed SC/FDE scheme over the straightforward SC/FDE which ignores the decisions errors at the intermediate relay nodes.

  8. Carrier frequency modulation of an acousto-optic modulator for laser stabilization.

    Science.gov (United States)

    Aldous, Matthew; Woods, Jonathan; Dragomir, Andrei; Roy, Ritayan; Himsworth, Matt

    2017-05-29

    The stabilization of lasers to absolute frequency references is a fundamental requirement in several areas of atomic, molecular and optical physics. A range of techniques are available to produce a suitable reference onto which one can 'lock' the laser, many of which depend on the specific internal structure of the reference or are sensitive to laser intensity noise. We present a novel method using the frequency modulation of an acousto-optic modulator's carrier (drive) signal to generate two spatially separated beams, with a frequency difference of only a few MHz. These beams are used to probe a narrow absorption feature and the difference in their detected signals leads to a dispersion-like feature suitable for wavelength stabilization of a diode laser. This simple and versatile method only requires a narrow absorption line and is therefore suitable for both atomic and cavity based stabilization schemes. To demonstrate the suitability of this method we lock an external cavity diode laser near the (85)Rb 5S1/2 → 5P3/2, F = 3 → F' = 4 using sub-Doppler pump probe spectroscopy and also demonstrate excellent agreement between the measured signal and a theoretical model.

  9. Multi-carrier transmission for hybrid radio frequency with optical wireless communications

    Science.gov (United States)

    Wang, Gang; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik; Nguyen, Tien M.

    2015-05-01

    Radio frequency (RF) wireless communication is reaching its capacity to support large data rate transmissions due to hardware constraints (e.g., silicon processes), software strategies (e.g., information theory), and consumer desire for timely large file exchanges (e.g., big data and mobile cloud computing). A high transmission rate performance must keep pace with the generated huge volumes of data for real-time processing. Integrated RF and optical wireless communications (RF/OWC) could be the next generation transmission technology to satisfy both the increased data rate exchange and the communications constraints. However, with the promising benefits of RF/OWC, challenges remain to fully develop hybrid RF with wireless optical communications such as uniform waveform design for information transmission and detection. In this paper, an orthogonal frequency division multiplexing (OFDM) transmission scheme, which widely employed in RF communications, is developed for optical communications. The traditional high peak-to-average power ratio (PAPR) in OFDM is reduced to improve system performance. The proposed multi-carrier waveform is evaluated with a frequency-selective fading channel. The results demonstrate that bit error rate (BER) performance of our proposed optical OFDM transmission technique outperforms the traditional OWC on-off keying (OOK) transmission scheme.

  10. Diversity Techniques for Single-Carrier Packet Retransmissions over Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Inbar Fijalkow

    2009-01-01

    Full Text Available In data packet communication systems over multipath frequency-selective channels, hybrid automatic repeat request (HARQ protocols are usually used in order to ensure data reliability. For single-carrier packet transmission in slow fading environment, an identical retransmission of the same packet, due to a decoding failure, does not fully exploit the available time diversity in retransmission-based HARQ protocols. In this paper, we compare two transmit diversity techniques, namely, cyclic frequency-shift diversity and bit-interleaving diversity. Both techniques can be integrated in the HARQ scheme in order to improve the performance of the joint detector. Their performance in terms of pairwise error probability is investigated using maximum likelihood detection and decoding. The impact of the channel memory and the modulation order on the performance gain is emphasized. In practice, we use low complexity linear filter-based equalization which can be efficiently implemented in the frequency domain. The use of iterative equalization and decoding is also considered. The performance gain in terms of frame error rate and data throughput is evaluated by numerical simulations.

  11. The frequency of Tay-Sachs disease causing mutations in the Brazilian Jewish population justifies a carrier screening program

    Directory of Open Access Journals (Sweden)

    Roberto Rozenberg

    Full Text Available CONTEXT: Tay-Sachs disease is an autosomal recessive disease characterized by progressive neurologic degeneration, fatal in early childhood. In the Ashkenazi Jewish population the disease incidence is about 1 in every 3,500 newborns and the carrier frequency is 1 in every 29 individuals. Carrier screening programs for Tay-Sachs disease have reduced disease incidence by 90% in high-risk populations in several countries. The Brazilian Jewish population is estimated at 90,000 individuals. Currently, there is no screening program for Tay-Sachs disease in this population. OBJECTIVE: To evaluate the importance of a Tay-Sachs disease carrier screening program in the Brazilian Jewish population by determining the frequency of heterozygotes and the acceptance of the program by the community. SETTING: Laboratory of Molecular Genetics - Institute of Biosciences - Universidade de São Paulo. PARTICIPANTS: 581 senior students from selected Jewish high schools. PROCEDURE: Molecular analysis of Tay-Sachs disease causing mutations by PCR amplification of genomic DNA, followed by restriction enzyme digestion. RESULTS: Among 581 students that attended educational classes, 404 (70% elected to be tested for Tay-Sachs disease mutations. Of these, approximately 65% were of Ashkenazi Jewish origin. Eight carriers were detected corresponding to a carrier frequency of 1 in every 33 individuals in the Ashkenazi Jewish fraction of the sample. CONCLUSION: The frequency of Tay-Sachs disease carriers among the Ashkenazi Jewish population of Brazil is similar to that of other countries where carrier screening programs have led to a significant decrease in disease incidence. Therefore, it is justifiable to implement a Tay-Sachs disease carrier screening program for the Brazilian Jewish population.

  12. Prevalence of common MEFV mutations and carrier frequencies in a large cohort of Iranian populations

    Indian Academy of Sciences (India)

    MARYAM BEHESHTIAN; NASIM IZADI; GERNOT KRIEGSHAUSER; KIMIA KAHRIZI; ELHAM PARSI MEHR; MARYAM ROSTAM; MASOUMEH HOSSEINI; MARYAM AZAD; MONA MONTAJABINIAT; ARIANA KARIMINEJAD; STEFAN NEMETH; CHRISTIAN OBERKANINS; HOSSEIN NAJMABADI

    2016-09-01

    Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by mutations in the MEFV gene. The disease is especially common among Armenian, Turkish, Jewish and Middle East Arab populations. To identify the frequency and the spectrum of common MEFV mutations in different Iranian populations, we investigated a cohort of 208 unselected asymptomatic individuals and 743 FMF patients. Nine hundred and fifty-one samples were analysed for the presence of 12 MEFV mutations by PCR and reverse-hybridization (FMF StripAssay, ViennaLab, Vienna, Austria). Confirmatory dideoxy sequencing of allMEFV gene exons was performed for 39 patients. Fifty-seven (27.4%) healthy individual carried mutant MEFV alleles. Three hundred and ninety-one (52.6%) FMF patients were found positive for either one (172/743; 23.1%), two or threeMEFV mutations. Using dideoxy sequencing, three novel variants, A66P, R202W and H300Q, could be identified. Our analysis revealed an allele frequency and carrier rate of 15.6 and 27.4%, respectively, among healthy Iranians. Stillmoderate compared to neighbouring Armenia, but higher than in Turkey or Iraq, these data suggest that FMF is remarkably common among Iranian populations. E148Q was most frequent in the group of healthy individuals, whereas M694V wasthe most common mutation among FMF patients, thereby corroborating previous studies on MEFV mutational spectra in the Middle East. Accordingly,MEFV mutations are frequent in healthy Iranian individuals across different ethnic groups. Based on this finding, the awareness for FMF and the implementation of augmented carrier screening programmes considering the multiethnic nature of the Iranian population should be promoted.

  13. Carrier phase recovery performance for PN-spread TDRSS link with radio-frequency interference

    Science.gov (United States)

    Mckenzie, T. M.; Braun, W. R.

    1979-01-01

    The carrier-phase recovery performance of a Costas loop for a nonlinear satellite channel with uplink and downlink noise is analyzed, and the extension of these results to the case where uplink radio-frequency interference (RFI) is present is considered. The signal format here is binary phase-shift-keyed (BPSK) or unbalanced quaternary phase-shift-keyed (UQPSK), the signals being either the non-return-to-zero (NRZ) or biphase (Manchester) type. With UQPSK, at least one data stream must be PN-spread. The channel comprises additive white Gaussian noise (WGN), a wideband filter, a bandpass nonlinearity and more additive WGN. The RFI being considered is pulsed continuous-wave, pulsed WGN, or a combination of the two. It is noted that the Tracking and Data Relay Satellite System (TDRSS) will be subjected to RFI from certain locations, especially in the S-band of frequencies. The characteristics of this link are generalized to form the assumptions underlying this analysis. The analytical results given include the S-curve of the equivalent loop and the phase-error variance of the linearized loop.

  14. Power density, field intensity, and carrier frequency determinants of RF-energy-induced calcium-ion efflux from brain tissue

    Energy Technology Data Exchange (ETDEWEB)

    Joines, W.T.; Blackman, C.F.

    1980-01-01

    To explain a carrier frequency dependence reported for radiofrequency (RF)-induced calcium-ion efflux from brain tissue, a chick-brain hemisphere bathed in buffer solution is modeled as a sphere within the uniform field of the incident electromagnetic wave. Calculations on a spherical model show that the average electric-field intensity within the sample remains the same at different carrier frequencies if the incident power density (Pi) is adjusted by an amount that compensates for the change in complex permittivity (epsilon *r) and the change of wavelength, as a function of carrier frequency. The resulting formula for transforming Pi is seen to follow the pattern of both positive and negative demonstrations of calcium-ion efflux that have been observed at carrier frequencies of 50, 147, and 450 MHz. Indeed, all results obtained at these three frequencies, when related by Pi's that produce the same average electric-field intensity within the sample, are seen to be in agreement; no prediction is contradicted by an experiment.

  15. FPGA-Based Implementation of All-Digital QPSK Carrier Recovery Loop Combining Costas Loop and Maximum Likelihood Frequency Estimator

    Directory of Open Access Journals (Sweden)

    Kaiyu Wang

    2014-01-01

    Full Text Available This paper presents an efficient all digital carrier recovery loop (ADCRL for quadrature phase shift keying (QPSK. The ADCRL combines classic closed-loop carrier recovery circuit, all digital Costas loop (ADCOL, with frequency feedward loop, maximum likelihood frequency estimator (MLFE so as to make the best use of the advantages of the two types of carrier recovery loops and obtain a more robust performance in the procedure of carrier recovery. Besides, considering that, for MLFE, the accurate estimation of frequency offset is associated with the linear characteristic of its frequency discriminator (FD, the Coordinate Rotation Digital Computer (CORDIC algorithm is introduced into the FD based on MLFE to unwrap linearly phase difference. The frequency offset contained within the phase difference unwrapped is estimated by the MLFE implemented just using some shifter and multiply-accumulate units to assist the ADCOL to lock quickly and precisely. The joint simulation results of ModelSim and MATLAB show that the performances of the proposed ADCRL in locked-in time and range are superior to those of the ADCOL. On the other hand, a systematic design procedure based on FPGA for the proposed ADCRL is also presented.

  16. Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation

    Science.gov (United States)

    Cunningham, Michael T.; Anderson, Leonard A.; Wilt, Kyle R.; Chakraborty, Soumya; Saulnier, Gary J.; Scarton, Henry A.

    2016-05-01

    Acoustic-electric channels can be used to send data through metallic barriers, enabling communications where electromagnetic signals are ineffective. This paper considers an acoustic-electric channel that is formed by mounting piezoelectric transducers on metallic barriers that are separated by a thin water layer. The transducers are coupled to the barriers using epoxy and the barriers are positioned to axially-align the PZTs, maximizing energy transfer efficiency. The electrical signals are converted by the transmitting transducers into acoustic waves, which propagate through the elastic walls and water medium to the receiving transducers. The reverberation of the acoustic signals in these channels can produce multipath distortion with a significant delay spread that introduces inter-symbol interference (ISI) into the received signal. While the multipath effects can be severe, the channel does not change rapidly which makes equalization easier. Here we implement a 16-QAM system on this channel, including a method for obtaining accurate carrier frequency offset (CFO) estimates in the presence of the quasi-static multipath propagation. A raised-power approach is considered but found to suffer from excessive data noise resulting from the ISI. An alternative approach that utilizes a pilot tone burst at the start of a data packet is used for CFO estimation and found to be effective. The autocorrelation method is used to estimate the frequency of the received burst. A real-time prototype of the 16 QAM system that uses a Texas Instruments MSP430 microcontroller-based transmitter and a personal computer-based receiver is presented along with performance results.

  17. Blind Estimation of the Phase and Carrier Frequency Offsets for LDPC-Coded Systems

    Directory of Open Access Journals (Sweden)

    Houcke Sebastien

    2010-01-01

    Full Text Available Abstract We consider in this paper the problem of phase offset and Carrier Frequency Offset (CFO estimation for Low-Density Parity-Check (LDPC coded systems. We propose new blind estimation techniques based on the calculation and minimization of functions of the Log-Likelihood Ratios (LLR of the syndrome elements obtained according to the parity check matrix of the error-correcting code. In the first part of this paper, we consider phase offset estimation for a Binary Phase Shift Keying (BPSK modulation and propose a novel estimation technique. Simulation results show that the proposed method is very effective and outperforms many existing algorithms. Then, we modify the estimation criterion so that it can work for higher-order modulations. One interesting feature of the proposed algorithm when applied to high-order modulations is that the phase offset of the channel can be blindly estimated without any ambiguity. In the second part of the paper, we consider the problem of CFO estimation and propose estimation techniques that are based on the same concept as the ones presented for the phase offset estimation. The Mean Squared Error (MSE and Bit Error Rate (BER curves show the efficiency of the proposed estimation techniques.

  18. A review on the inter-frequency biases of GLONASS carrier-phase data

    Science.gov (United States)

    Geng, Jianghui; Zhao, Qile; Shi, Chuang; Liu, Jingnan

    2016-10-01

    GLONASS ambiguity resolution (AR) between inhomogeneous stations requires correction of inter-frequency phase biases (IFPBs) (a "station" here is an integral ensemble of a receiver, an antenna, firmware, etc.). It has been elucidated that IFPBs as a linear function of channel numbers are not physical in nature, but actually originate in differential code-phase biases (DCPBs). Although IFPBs have been prevalently recognized, an unanswered question is whether IFPBs and DCPBs are equivalent in enabling GLONASS AR. Besides, general strategies for the DCPB estimation across a large network of heterogeneous stations are still under investigation within the GNSS community, such as whether one DCPB per receiver type (rather than individual stations) suffices, as tentatively suggested by the IGS (International GNSS Service), and what accuracy we are able to and ought to achieve for DCPB products. In this study, we review the concept of DCPBs and point out that IFPBs are only approximate derivations from DCPBs, and are potentially problematic if carrier-phase hardware biases differ by up to several millimeters across frequency channels. We further stress the station and observable specific properties of DCPBs which cannot be thoughtlessly ignored as conducted conventionally. With 212 days of data from 200 European stations, we estimated DCPBs per stations by resolving ionosphere-free ambiguities of ˜ 5.3 cm wavelengths, and compared them to the presumed truth benchmarks computed directly with L1 and L2 data on ultra-short baselines. On average, the accuracy of our DCPB products is around 0.7 ns in RMS. According to this uncertainty estimates, we could unambiguously confirm that DCPBs can typically differ substantially by up to 30 ns among receivers of identical types and over 10 ns across different observables. In contrast, a DCPB error of more than 6 ns will decrease the fixing rate of ionosphere-free ambiguities by over 20 %, due to their smallest frequency spacing and

  19. Spectrotemporal modulation sensitivity for hearing-impaired listeners: dependence on carrier center frequency and the relationship to speech intelligibility.

    Science.gov (United States)

    Mehraei, Golbarg; Gallun, Frederick J; Leek, Marjorie R; Bernstein, Joshua G W

    2014-07-01

    Poor speech understanding in noise by hearing-impaired (HI) listeners is only partly explained by elevated audiometric thresholds. Suprathreshold-processing impairments such as reduced temporal or spectral resolution or temporal fine-structure (TFS) processing ability might also contribute. Although speech contains dynamic combinations of temporal and spectral modulation and TFS content, these capabilities are often treated separately. Modulation-depth detection thresholds for spectrotemporal modulation (STM) applied to octave-band noise were measured for normal-hearing and HI listeners as a function of temporal modulation rate (4-32 Hz), spectral ripple density [0.5-4 cycles/octave (c/o)] and carrier center frequency (500-4000 Hz). STM sensitivity was worse than normal for HI listeners only for a low-frequency carrier (1000 Hz) at low temporal modulation rates (4-12 Hz) and a spectral ripple density of 2 c/o, and for a high-frequency carrier (4000 Hz) at a high spectral ripple density (4 c/o). STM sensitivity for the 4-Hz, 4-c/o condition for a 4000-Hz carrier and for the 4-Hz, 2-c/o condition for a 1000-Hz carrier were correlated with speech-recognition performance in noise after partialling out the audiogram-based speech-intelligibility index. Poor speech-reception and STM-detection performance for HI listeners may be related to a combination of reduced frequency selectivity and a TFS-processing deficit limiting the ability to track spectral-peak movements.

  20. The method of «blind» carrier frequency estimation of radio signals with linear digital modulation

    Directory of Open Access Journals (Sweden)

    Nahornyuk О.А.

    2017-04-01

    Full Text Available Carrier frequency estimation in the conditions of a priori uncertainty of signal modulation and parameters is prerequisite for realization of frequency synchronization circuits in software-defined radio. To implement this operation the method of «blind» carrier frequency estimation of radio signals with amplitude, phase and quadrature-amplitude shift keying, which does not require prior information about modulation type, signal and communication channel parameters, is proposed in the article. The basis of method is calculation of constellation symbols cross-correlation and clock synchronization by Gardner method. As opposed to known approaches proposed method does not require two-dimensional objective function calculation which can reduce the number of computing operations. This is achieved by implementation of previous clock synchronization and reducing the two-dimensional objective function in one-dimensional. Verification of developed method is carried out by statistical modeling using more than 20 types of phase constellations. The practical significance of received results consists in reduction of carrier frequency estimation time and simplification of practical implementation at the expense of employment of approved clock synchronization circuits.

  1. Efficient and Robust Detection of GFSK Signals under Dispersive Channel, Modulation Index, and Carrier Frequency Offset Conditions

    Directory of Open Access Journals (Sweden)

    Stephan Weiss

    2005-09-01

    Full Text Available Gaussian frequency shift keying is the modulation scheme specified for Bluetooth. Signal adversities typical in Bluetooth networks include AWGN, multipath propagation, carrier frequency, and modulation index offsets. In our effort to realise a robust but efficient Bluetooth receiver, we adopt a high-performance matched-filter-based detector, which is near optimal in AWGN, but requires a prohibitively costly filter bank for processing of K bits worth of the received signal. However, through filtering over a single bit period and performing phase propagation of intermediate results over successive single-bit stages, we eliminate redundancy involved in providing the matched filter outputs and reduce its complexity by up to 90% (for K=9. The constant modulus signal characteristic and the potential for carrier frequency offsets make the constant modulus algorithm (CMA suitable for channel equalisation, and we demonstrate its effectiveness in this paper. We also introduce a stochastic gradient-based algorithm for carrier frequency offset correction, and show that the relative rotation between successive intermediate filter outputs enables us to detect and correct offsets in modulation index.

  2. Word frequency and content analysis approach to identify demand patterns in a virtual community of carriers of hepatitis C.

    Science.gov (United States)

    Vasconcellos-Silva, Paulo Roberto; Carvalho, Darlinton; Lucena, Carlos

    2013-07-04

    Orkut, a Brazilian virtual social network, is responsible for popularization of the Internet among people of low income and educational level. It's observed that rapid growth of virtual communities can be reached by low cost Internet access in community local area network houses. Orkut poses an important social resource for Brazilian patients with chronic conditions like hepatitis C virus (HCV) carriers, who face several obstacles in adapting to everyday difficulties. Identify Patterns of Recurring Demands (PRD) expressed in messages posted by members of virtual communities dedicated to HCV carriers. Pre-selection: we identified terms commonly associated to HCV on generic Internet searches (primary Keywords - Kps); Kps were used to identify the most representative HCV communities in a virtual community site (Orkut); all messages published along 8 years on all topics of the community were collected and tabulated; the word frequency was used to construct a "word cloud" (graphic representation of the word frequency) on which was applied a content analysis technique. The most cited terms expressed: search for information about medications (prescribed and "forbidden"); emphasis on counting time, which were interpreted as surviving expectations; frequent mention of God, doctors, and "husbands" (female carriers were 68%). These elements provided material for further research - they will be useful in the construction of categories in discourse analysis. The present work is a disclosure of preliminary findings considered original and promising. The word frequency/content analysis approach expressed needs of social support and material assistance that may provide subsidies for further qualitative approach and public health policies aimed to HCV carriers. The study of PRD by word frequency may be useful in identifying demands underestimated by other means.

  3. ANALYSIS OF REDUCTION IN COMPLEXITY OF MULTIPLE INPUT- MULTIPLE OUTPUT-ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEMS WITH CARRIER FREQUENCY OFFSET ESTIMATION AND CORRECTION

    Directory of Open Access Journals (Sweden)

    Sabitha Gauni

    2014-01-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM is a promising research area in Wireless Communication for high data rates. The Multiple Input-Multiple Output (MIMO technology when incorporated with the OFDM system promise a significant boost in the performance. But, the MIMO-OFDM systems are very sensitive to Carrier Frequency Offset (CFO as it deteriorates the system performance with the rise of Inter-Carrier-Interference (ICI. A theoretical analysis to evaluate the performance of Orthogonal Frequency Division Multiplexing (OFDM systems is done here, under the combined influence of Phase Offset and Frequency Offset over Rayleigh, Weibull and Nakagami fading channels using Binary Phase Shift Keying (BPSK Modulation. The analysis of increase in Bit Error Rate (BER caused by the presence of Phase Offset and Frequency Offset is evaluated assuming Gaussian probability density function. Hence the estimation and correction of CFO plays a vital role in MIMO-OFDM systems. A method for CFO estimation and correction is analyzed in the MIMO-OFDM system with 16-QAM modulation. In non-pilot-aided systems the CFO acquisition is done using Maximum Likelihood Estimation (MLE algorithm. The proposed scheme uses the same block for CFO correction of MIMO-OFDM symbols. Since the same phase calculation block is used for the ML estimation along with the acquisition, the computational cost and the complexity of implementation is reduced.

  4. Discrimination and Identification of Modulation-Frequency Using Noise, Tone, and Tonal-Complex Carriers

    Science.gov (United States)

    1988-05-23

    frequency. For these frequencies, identification performance was almost as good as discrimination performance. This " edge effect " is commonly...if the edge effect acts over a fixed frequency range, then the better relative performance at the lower frequencies may be due to the edge effect rather

  5. Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

    Directory of Open Access Journals (Sweden)

    Chin Francois

    2004-01-01

    Full Text Available Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on single-carrier cyclic prefix-assisted CDMA has been proposed to overcome the disadvantages of single-carrier CDMA and multicarrier modulation. The usefulness of the proposed approach for high-speed packet access with simplified channel estimation procedures are investigated in this paper. The paper also proposes a data-dependent pilot structure for the downlink transmission of the proposed system for enhancing pilot-assisted channel estimation in frequency domain. The performance of the proposed pilot structure is compared against the data-independent common pilot structure. The proposed system is extensively simulated for different channel parameters with different channel estimation and equalization methods and the results are compared against conventional multicarrier CDMA systems with identical system specifications.

  6. Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

    Directory of Open Access Journals (Sweden)

    Madhukumar A. S.

    2004-01-01

    Full Text Available Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on single-carrier cyclic prefix-assisted CDMA has been proposed to overcome the disadvantages of single-carrier CDMA and multicarrier modulation. The usefulness of the proposed approach for high-speed packet access with simplified channel estimation procedures are investigated in this paper. The paper also proposes a data-dependent pilot structure for the downlink transmission of the proposed system for enhancing pilot-assisted channel estimation in frequency domain. The performance of the proposed pilot structure is compared against the data-independent common pilot structure. The proposed system is extensively simulated for different channel parameters with different channel estimation and equalization methods and the results are compared against conventional multicarrier CDMA systems with identical system specifications.

  7. Performance Evaluation of WPMCM with Carrier Frequency Offset and Phase Noise

    NARCIS (Netherlands)

    Karamehmedovic, D.; Lakshmanan, M.K.; Nikookar, H.

    2009-01-01

    Wavelet Packet based Multi-Carrier Modulation (WPMCM) offers an alternative to the well-established OFDM as an efficient multicarrier modulation technique. It has strong advantage of being a generic transmission scheme whose actual characteristics can be widely customized to fulfill several requirem

  8. Generation of coherent and frequency-lock multi-carriers using cascaded phase modulators and recirculating frequency shifter for Tb/s optical communication.

    Science.gov (United States)

    Zhang, Junwen; Chi, Nan; Yu, Jianjun; Shao, Yufeng; Zhu, Jiangbo; Huang, Bo; Tao, Li

    2011-07-04

    We investigate to generate coherent and frequency-lock optical multi-carriers by using cascaded phase modulators and recirculating frequency shifter (RFS) based on an EDFA loop. The phase and amplitude relation of RF signals on two cascaded phase modulators and the impact of EDFA gain are investigated. Experimental results are in good agreement with the theoretical analysis. The performance of 113 coherent and frequency-lock subcarriers with tone-to-noise ratio larger than 26dB and amplitude difference of 5dB obtained after a tilt filter covering totally 22.6nm shows that this scheme is a promising technique for the coming Tb/s optical communication.

  9. Generation of tunable, high repetition rate frequency combs with equalized spectra using carrier injection based silicon modulators

    Science.gov (United States)

    Nagarjun, K. P.; Selvaraja, Shankar Kumar; Supradeepa, V. R.

    2016-03-01

    High repetition-rate frequency combs with tunable repetition rate and carrier frequency are extensively used in areas like Optical communications, Microwave Photonics and Metrology. A common technique for their generation is strong phase modulation of a CW-laser. This is commonly implemented using Lithium-Niobate based modulators. With phase modulation alone, the combs have poor spectral flatness and significant number of missing lines. To overcome this, a complex cascade of multiple intensity and phase modulators are used. A comb generator on Silicon based on these principles is desirable to enable on-chip integration with other functionalities while reducing power consumption and footprint. In this work, we analyse frequency comb generation in carrier injection based Silicon modulators. We observe an interesting effect in these comb generators. Enhanced absorption accompanying carrier injection, an undesirable effect in data modulators, shapes the amplitude here to enable high quality combs from a single modulator. Thus, along with reduced power consumption to generate a specific number of lines, the complexity has also been significantly reduced. We use a drift-diffusion solver and mode solver (Silvaco TCAD) along with Soref-Bennett relations to calculate the variations in refractive indices and absorption of an optimized Silicon PIN - waveguide modulator driven by an unbiased high frequency (10 Ghz) voltage signal. Our simulations demonstrate that with a device length of 1 cm, a driving voltage of 2V and minor shaping with a passive ring-resonator filter, we obtain 37 lines with a flatness better than 5-dB across the band and power consumption an order of magnitude smaller than Lithium-Niobate modulators.

  10. A Novel Multi-carrier Radar for High-speed Wide-bandwidth Stepped-Frequency GPR

    Science.gov (United States)

    Kyoo Kim, Dong; Choi, Young Woo; Kang, Do Wook

    2015-04-01

    the paved road. To make it fast, the frequency step or the dwell time can be varied. But, increasing the frequency step affects the scanning time range performance, and decreasing the dwell time reduces SNR. In this paper, we introduce a novel multi-carrier radar technique, the step frequency multi-carrier (SFMC) which sends multiple CW signals simultaneously to speed up the scanning operation, where no reduction of the frequency step and the dwell time is required. In this paper, we apply the orthogonal frequency division multiplexing technique to the simultaneous sending of multiple CW signals. The suggested technique is in the category of the stepped-frequency GPR in that they are based on the frequency domain measurement. They have theoretically almost the same accuracy and SNR. But the scanning time of the suggested technique is incomparably fast than stepped-frequency GPR; hundreds of CW signals can be radiated at one time. To get the nice property, we need to pay additional signal processing process for it. In this paper, we handle the signal processing about impairments such as DC frequency, phase discontinuity, channel estimation, and frequency-edge non-linearity problem. Some simulation and experimental results are shown to address the impairments and performance of the suggested technique.

  11. Digital coherent detection of multi-gigabit 40 GHz carrier frequency radio-over-fiber signals using photonic downconversion

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Tafur Monroy, Idelfonso

    Detection of high speed radio signals is a challenge for next generation radio-over-fiber links, requiring high bandwidth and linearity in the receiver. By using photonic downconversion in a coherent receiver, it is possible to detect signals exceeding the electrical bandwidth of the receiver......, by performing the mixing of the radio signal with a free-running local oscillator in the optical domain. In this paper we present the experimental emonstration of high bitrate 16-QAM signal detection, up to 4 Gb/s, at 40 GHz carrier frequency, using low bandwidth electronics....

  12. TURBO AIDED CYCLIC PREFIX RECONSTRUCTION FOR CODED SINGLE-CARRIER SYSTEMS WITH FREQUENCY-DOMAIN EQUALIZATION (SC-FDE)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, a Turbo aided Cyclic Prefix (CP) reconstruction scheme, termed Turbo-CPR, is proposed for Single-Carrier systems with Frequency-Domain Equalization (SC-FDE) that employ insufficient CP in the transmitter. In Turbo-CPR, the decoder output is incorporated in the process of equalization, i.e. Turbo equalizer is employed. It is shown in the simulation results that Turbo-CPR not only recovers the performance loss due to insufficiency of CP, but also provides extra gains over the lower bound of performance for conventional CP reconstruction schemes.

  13. Sub-carrier and band hopped orthogonal frequency division multiple access (OFDMA) systems

    DEFF Research Database (Denmark)

    Rahman, Muhammad Imadur; Reynisson, Ragnar Vidir; Figueiredo, Daniel Vaz Pato

    2009-01-01

    This article proposes a novel way of grouping users in an orthogonal frequency division multiplexing (OFDM) communication link based on predefined criteria. The total available spectrum is divided into a number of bands equal to the number of groups. For efficient time-frequency resource allocati...

  14. Carrier shock and frequency conversion of a few-cycle pulse laser propagating in a non-resonant two-level atom medium

    Institute of Scientific and Technical Information of China (English)

    肖健; 王中阳; 徐至展

    2002-01-01

    We have studied the spectral behaviour of few-cycle soliton pulses in a non-resonant two-level atom medium by solving the full Maxwell-Bloch equations. It is demonstrated further that the carrier effects play an important role in the propagation of the few-cycle pulse laser. When the frequency detuning is not very large, both the population distribution and the refractive index of the medium follow the oscillatory carrier field instantaneously; in this case,carrier-wave compression or carrier shock occurs, and a supercontinuum broader than that in the resonant medium may be generated. When the frequency detuning is large, the carrier shock is weak and the spectrum is not continuous, only showing an odd harmonic radiation.

  15. DWDM Fiber-Wireless Access System with Centralized Optical Frequency Comb-based RF Carrier Generation

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltrán, Marta; Sánchez, José;

    2013-01-01

    We propose and experimentally demonstrate an optical wireless DWDM system at 60 GHz with optical incoherent heterodyne up-conversion using an optical frequency comb. Multiple users with wireline and wireless services are simultaneously supported.......We propose and experimentally demonstrate an optical wireless DWDM system at 60 GHz with optical incoherent heterodyne up-conversion using an optical frequency comb. Multiple users with wireline and wireless services are simultaneously supported....

  16. Phase-stabilization of the carrier-envelope-offset frequency of a SESAM modelocked thin disk laser.

    Science.gov (United States)

    Klenner, Alexander; Emaury, Florian; Schriber, Cinia; Diebold, Andreas; Saraceno, Clara J; Schilt, Stéphane; Keller, Ursula; Südmeyer, Thomas

    2013-10-21

    We phase-stabilized the carrier-envelope-offset (CEO) frequency of a SESAM modelocked Yb:CaGdAlO₄ (CALGO) thin disk laser (TDL) generating 90-fs pulses at a center wavelength of 1051.6 nm and a repetition rate of 65 MHz. By launching only 2% of its output power into a photonic crystal fiber, we generated a coherent octave-spanning supercontinuum spectrum. Using a standard f-to-2f interferometer for CEO detection, we measured CEO beats with 33 dB signal-to-noise ratio in 100 kHz resolution bandwidth. We achieved a tight lock of the CEO frequency at 26.18 MHz by active feedback to the pump current. The residual in-loop integrated phase noise is 120 mrad (1 Hz-1 MHz). This is, to our knowledge, the first CEO-stabilized SESAM modelocked TDL. Our results show that a reliable lock of the CEO frequency can be achieved using standard techniques in spite of the strongly spatially multimode pumping scheme of TDLs. This opens the door towards fully-stabilized low-noise frequency combs with hundreds of watts of average power from table-top SESAM modelocked thin disk oscillators.

  17. Interference-Cancellation-Based Carrier Frequency Offset Estimation for OFDMA Uplink Transmissions

    Institute of Scientific and Technical Information of China (English)

    SU Huan; ZHANG Chao; LU Jianhua

    2009-01-01

    A carder frequency offset (CFO) estimator was developed based on an interference cancellation scheme for an orthogonal frequency division multiplex access uplink. An initial CFO estimate was first ob-tained based on the received training signals at each user's prescribed subcarder positions. Then, the re-ceived training signals were compensated by using the initial CFO estimates in the frequency domain and the multi-user interferences were estimated. Finally, the interference-cancelled training signals were used to reliably estimate each user's CFO. The CFO estimator performance was evaluated by the bit error rate per-formances of the CFO compensation-based receivers at the base station. Simulations show that with this optimal interference-cancellation-based CFO compensation receiver, the performance gain with the esti-mated CFO values is approximately 3 dB better at the 0.1% bit error rate than the initial CFO estimates.

  18. High-Frequency Link Inverter for Fuel Cells Based on Multiple-Carrier PWM

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    HIGH-FREQUENCY (I-IF) ac link inverter topologies, with or without soft switching, have important practical advantages compared to more conventional dc link inverters in terms of isolation, size of magnetics, and other properties. It is possible to obtain these basic advantages directly in a conventional PWM inverter with trans former-coupled output, but only if the transformer can handle the low modulating frequency. HF link topologies have not been common for medium power (1 to 20kW), largely because of the number of power stages and control complexity.

  19. Centralized optical-frequency-comb-based RF carrier generator for DWDM fiber-wireless access systems

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltran, Marta; Sanchez, Jose;

    2014-01-01

    In this paper, we report on a gigabit capacity fiber-wireless system that enables smooth integration between high-speed wireless networks and dense wavelength-division-multiplexing (DWDM) access networks. By employing a centralized optical frequency comb, both the wireline and the wireless services....... For demonstration, we transmit a 2.5 Gbit/s signal through the proposed system and successfully achieve a bit-error-rate (BER) performance well below the 7% overhead forward error correction limit of the BER of 2 × 10¿3 for both the wireline and the wireless signals in the 60 GHz band after 25 km single-mode fiber...... for each DWDM user can be simultaneously supported. Besides, each baseband channel can be transparently upconverted tomultiple radio-frequency (RF) bands for different wireless standards, which can be flexibly filtered at the end user to select the on-demand RF band, depending on the wireless applications...

  20. Low noise optical multi-carrier generation using optical-FIR filter for ASE noise suppression in re-circulating frequency shifter loop.

    Science.gov (United States)

    Lin, Jiachuan; Xi, Lixia; Li, Jianrui; Zhang, Xiaoguang; Zhang, Xia; Niazi, Shahab Ahmad

    2014-04-07

    In this paper, an improved multi-carrier generation scheme based on single-side-band recirculating frequency shifter with optical finite impulse response (FIR) filter for amplified spontaneous emission (ASE) noise suppression is proposed and experimentally demonstrated. The carrier-to-noise-ratio (CNR) instead of tone-to-noise-ratio (TNR) is introduced to more reasonably and exactly evaluate the signal-to-noise-ratio of a multi-carrier source with non-flat noise floor. We have experimentally attain the worst case CNR of 22.5dB and 19.1dB for generated 50 and 69 flat low noise carriers, which has shown significant improvement than the previous cited works based on recirculating frequency shifter.

  1. Effects of Carrier Frequency Offset, Timing Offset, and Channel Spread Factor on the Performance of Hexagonal Multicarrier Modulation Systems

    Directory of Open Access Journals (Sweden)

    Xu Kui

    2009-01-01

    Full Text Available Abstract Hexagonal multicarrier modulation (HMM system is the technique of choice to overcome the impact of time-frequency dispersive transmission channel. This paper examines the effects of insufficient synchronization (carrier frequency offset, timing offset on the amplitude and phase of the demodulated symbol by using a projection receiver in hexagonal multicarrier modulation systems. Furthermore, effects of CFO, TO, and channel spread factor on the performance of signal-to-interference-plus-noise ratio (SINR in hexagonal multicarrier modulation systems are further discussed. The exact SINR expression versus insufficient synchronization and channel spread factor is derived. Theoretical analysis shows that similar degradation on symbol amplitude and phase caused by insufficient synchronization is incurred as in traditional cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM transmission. Our theoretical analysis is confirmed by numerical simulations in a doubly dispersive (DD channel with exponential delay power profile and U-shape Doppler power spectrum, showing that HMM systems outperform traditional CP-OFDM systems with respect to SINR against ISI/ICI caused by insufficient synchronization and doubly dispersive channel.

  2. Effects of Carrier Frequency Offset, Timing Offset, and Channel Spread Factor on the Performance of Hexagonal Multicarrier Modulation Systems

    Directory of Open Access Journals (Sweden)

    Kui Xu

    2009-01-01

    Full Text Available Hexagonal multicarrier modulation (HMM system is the technique of choice to overcome the impact of time-frequency dispersive transmission channel. This paper examines the effects of insufficient synchronization (carrier frequency offset, timing offset on the amplitude and phase of the demodulated symbol by using a projection receiver in hexagonal multicarrier modulation systems. Furthermore, effects of CFO, TO, and channel spread factor on the performance of signal-to-interference-plus-noise ratio (SINR in hexagonal multicarrier modulation systems are further discussed. The exact SINR expression versus insufficient synchronization and channel spread factor is derived. Theoretical analysis shows that similar degradation on symbol amplitude and phase caused by insufficient synchronization is incurred as in traditional cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM transmission. Our theoretical analysis is confirmed by numerical simulations in a doubly dispersive (DD channel with exponential delay power profile and U-shape Doppler power spectrum, showing that HMM systems outperform traditional CP-OFDM systems with respect to SINR against ISI/ICI caused by insufficient synchronization and doubly dispersive channel.

  3. Multi-user interference cancellation schemes for carrier frequency offset compensation in uplink OFDMA

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; De Carvalho, Elisabeth; Prasad, Ramjee

    2014-01-01

    the system performance severely. In this paper, novel time-domain multi-user interference cancellation schemes for OFDMA uplink are proposed. They employ an architecture with multiple and numerical evaluations show that the proposed schemes achieve a significant performance gain compared to the conventional...... receiver and a reference frequency-domain multi-user interference cancellation scheme. In a particular scenario, a maximum CFO of up to 40% of the subcarrier spacing can be tolerated, and the CFO-free performance is maintained in the OFDMA uplink. The proposed schemes outperform the multi-user interference...

  4. Employing GPS L5 Carrier-Frequency in Precise Point Positioning

    Science.gov (United States)

    Spits, J.; Santos, M. C.

    2012-12-01

    Justine Spits and Marcelo C. Santos Dept. of Geodesy and Geomatics Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 Tel: (1-506) 453-4698, Email: msantos@unb.ca, jspits@unb.ca Precise Point Positioning (PPP) is a GNSS technique which, in most cases nowadays, makes use of Global Positioning System (GPS) dual-frequency signals. The increasing availability of the new GPS L5 signal brings about the question on how much can PPP benefit if it uses L5 in conjunction with the legacy L1 and L2 signals. This poster discusses this issue. It involves the study of the use of L5 in conjunction with the other GPS signals (L1 and L2) with emphasis on the potentialities associated with the various combinations, such as L1-L5, L2-L5 and L1-L2-L5. These combinations will bring benefits in different ways, for example, for ionospheric delay mitigation, ambiguity resolution, convergence time and accuracy. Simulated L5 data will be used to test the PPP algorithms. Performance will be compared against the current dual-frequency PPP methodology. Justine Spits: Ph.D. (Liège, Belgium); Post-Doctoral Fellow, University of New Brunswick Marcelo. C. Santos: Ph.D. (New Brunswick); Professor, University of New Brunswick

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

    Science.gov (United States)

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

    2017-04-01

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

  6. Theoretical analysis of polarization control for the stable output of multi-carrier source based on a re-circulating frequency shifter

    Institute of Scientific and Technical Information of China (English)

    Hao Zhou; Lixia Xi; Jianping Li; Xiaoguang Zhang; Na Liu

    2012-01-01

    Fluctuating polarization state-of-light in the optical loop is an important factor that seriously influences the output performance of a multi-carrier source based on re-circulating frequency shifter (RFS).The reason for output spectrum instability when no polarization controller (PC) is present in the loop is analyzed theoretically.Numerical simulations for the output spectra of the multi-carrier source with and without PC are conducted,and the trajectories of the several frequency components polarization states on the Poincare sphere with and without PC are compared.The results show that the performance of multi-carrier source based on a RFS can be improved effectively by adjusting the PC in the configuration properly.

  7. Carrier phase dependence in the ionization of Rydberg atoms by short radio-frequency pulses: A model system for high order harmonic generation

    NARCIS (Netherlands)

    Gurtler, A.; Robicheaux, F.; Vrakking, M.J.J.; Zande, W.J. van der; Noordam, L.D.

    2004-01-01

    We report time-resolved electron emission in experiments on ionization of rubidium Rydberg atoms (n=90) by few-cycle radio-frequency (RF) (1-10 MHz) pulses. The electron emission occurs in multiple bursts and strongly depends on the carrier-envelope phase as well as the duration and amplitude of the

  8. Cooperative Transmission in Mobile Wireless Sensor Networks with Multiple Carrier Frequency Offsets: A Double-Differential Approach

    Directory of Open Access Journals (Sweden)

    Kun Zhao

    2014-01-01

    Full Text Available As a result of the rapidly increasing mobility of sensor nodes, mobile wireless sensor networks (MWSNs would be subject to multiple carrier frequency offsets (MCFOs, which result in time-varying channels and drastically degrade the network performance. To enhance the performance of such MWSNs, we propose a relay selection (RS based double-differential (DD cooperative transmission scheme, termed RSDDCT, in which the best relay sensor node is selected to forward the source sensor node’s signals to the destination sensor node with the detect-and-forward (DetF protocol. Assuming a Rayleigh fading environment, first, exact closed-form expressions for the outage probability and average bit error rate (BER of the RSDDCT scheme are derived. Then, simple and informative asymptotic outage probability and average BER expressions at the large signal-to-noise ratio (SNR regime are presented, which reveal that the RSDDCT scheme can achieve full diversity. Furthermore, the optimum power allocation strategy in terms of minimizing the average BER is investigated, and simple analytical solutions are obtained. Simulation results demonstrate that the proposed RSDDCT scheme can achieve excellent performance over fading channels in the presence of unknown random MCFOs. It is also shown that the proposed optimum power allocation strategy offers substantial average BER performance improvement over the equal power allocation strategy.

  9. Relay Selection Based Double-Differential Transmission for Cooperative Networks with Multiple Carrier Frequency Offsets: Model, Analysis, and Optimization

    Science.gov (United States)

    Zhao, Kun; Zhang, Bangning; Pan, Kegang; Liu, Aijun; Guo, Daoxing

    2014-07-01

    Due to the distributed nature, cooperative networks are generally subject to multiple carrier frequency offsets (MCFOs), which make the channels time-varying and drastically degrade the system performance. In this paper, to address the MCFOs problem in detect-andforward (DetF) multi-relay cooperative networks, a robust relay selection (RS) based double-differential (DD) transmission scheme, termed RSDDT, is proposed, where the best relay is selected to forward the source's double-differentially modulated signals to the destination with the DetF protocol. The proposed RSDDT scheme can achieve excellent performance over fading channels in the presence of unknown MCFOs. Considering double-differential multiple phase-shift keying (DDMPSK) is applied, we first derive exact expressions for the outage probability and average bit error rate (BER) of the RSDDT scheme. Then, we look into the high signal-to-noise ratio (SNR) regime and present simple and informative asymptotic outage probability and average BER expressions, which reveal that the proposed scheme can achieve full diversity. Moreover, to further improve the BER performance of the RSDDT scheme, we investigate the optimum power allocation strategy among the source and the relay nodes, and simple analytical solutions are obtained. Numerical results are provided to corroborate the derived analytical expressions and it is demonstrated that the proposed optimum power allocation strategy offers substantial BER performance improvement over the equal power allocation strategy.

  10. GJB2 and mitochondrial A1555G gene mutations in nonsyndromic profound hearing loss and carrier frequencies in healthy individuals

    Indian Academy of Sciences (India)

    Elif Baysal; Yildirim A. Bayazit; Serdar Ceylaner; Necat Alatas; Buket Donmez; Gulay Ceylaner; Imran San; Baki Korkmaz; Akin Yilmaz; Adnan Menevse; Senay Altunyay; Bulent Gunduz; Nebil Goksu; Ahmet Arslan; Abdullah Ekmekci

    2008-04-01

    This study aimed to assess mutations in GJB2 gene (connexin 26), as well as A1555G mitochondrial mutation in both the patients with profound genetic nonsyndromic hearing loss and healthy controls. Ninety-five patients with profound hearing loss (>90 dB) and 67 healthy controls were included. All patients had genetic nonsyndromic hearing loss. Molecular analyses were performed for connexin 26 (35delG, M34T, L90P, R184P, delE120, 167delT, 235delC and IVS1+1 A → G) mutations, and for mitochondrial A1555G mutation. Twenty-two connexin 26 mutations were found in 14.7% of the patients, which were 35delG, R184P, del120E and IVS1+1 A → G. Mitochondrial A1555G mutation was not encountered. The most common GJB2 gene mutation was 35delG, which was followed by del120E, IVS1+1 A → G and R184P, and 14.3% of the patients segregated with DFNB1. In consanguineous marriages, the most common mutation was 35delG. The carrier frequency for 35delG mutation was 1.4% in the controls. 35delG and del120E populations, seems the most common connexin 26 mutations that cause genetic nonsyndromic hearing loss in this country. Nonsyndromic hearing loss mostly shows DFNB1 form of segregation.

  11. Reverse Link Outage Probabilities of Multicarrier CDMA Systems with Beamforming in the Presence of Carrier Frequency Offset

    Directory of Open Access Journals (Sweden)

    Xiaoyu Hu

    2007-11-01

    Full Text Available The outage probability of reverse link multicarrier (MC code-division multiple access (CDMA systems with beamforming in the presence of carrier frequency offset (CFO is studied. A conventional uniform linear array (ULA beamformer is utilized. An independent Nakagami fading channel is assumed for each subcarrier of all users. The outage probability is first investigated under a scenario where perfect beamforming is assumed. A closed form expression of the outage probability is derived. The impact of different types of beamforming impairments on the outage probability is then evaluated, including direction-of-arrival (DOA estimation errors, angle spreads, and mutual couplings. Numerical results show that the outage probability improves significantly as the number of antenna elements increases. The effect of CFO on the outage probability is reduced significantly when the beamforming technique is employed. Also, it is seen that small beamforming impairments (DOA estimation errors and angle spreads only affect the outage probability very slightly, and the mutual coupling between adjacent antenna elements does not affect the outage probability noticeably.

  12. Reverse Link Outage Probabilities of Multicarrier CDMA Systems with Beamforming in the Presence of Carrier Frequency Offset

    Directory of Open Access Journals (Sweden)

    Hu Xiaoyu

    2008-01-01

    Full Text Available The outage probability of reverse link multicarrier (MC code-division multiple access (CDMA systems with beamforming in the presence of carrier frequency offset (CFO is studied. A conventional uniform linear array (ULA beamformer is utilized. An independent Nakagami fading channel is assumed for each subcarrier of all users. The outage probability is first investigated under a scenario where perfect beamforming is assumed. A closed form expression of the outage probability is derived. The impact of different types of beamforming impairments on the outage probability is then evaluated, including direction-of-arrival (DOA estimation errors, angle spreads, and mutual couplings. Numerical results show that the outage probability improves significantly as the number of antenna elements increases. The effect of CFO on the outage probability is reduced significantly when the beamforming technique is employed. Also, it is seen that small beamforming impairments (DOA estimation errors and angle spreads only affect the outage probability very slightly, and the mutual coupling between adjacent antenna elements does not affect the outage probability noticeably.

  13. Time-Frequency Filtering and Carrier-Phase Ambiguity Resolution for GPS-Based TSPI Systems in Jamming Environment

    Science.gov (United States)

    2007-08-15

    34Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments," Journal of Geodesy 81, 149-156 (2007). * A...and S. Mahmood "Efficiency of carrier-phase integer ambiguity resolution for precise GPS positioning in noisy environments," Journal of Geodesy 81...was an active collaboration with Drs. S. Mohamod and J. Murchison at Eglin AFB. The activities resulted in one joint paper published in Journal of Geodesy . During

  14. GLONASS三种载波频率组合值研究%RESEARCH ON THREE KINDS OF CARRIER FREQUENCY COMBINATION VALUE OF GLONASS

    Institute of Scientific and Technical Information of China (English)

    徐军; 陶庭叶; 高飞

    2013-01-01

    研究了GLAONASS三种频率载波相位组合方法,以模糊度保持整数为前提,通过分析电离层延迟和观测噪声对三频组合观测值的影响,依据线性组合的长波长标准、弱电离层延迟标准、弱观测噪声标准,得出了一些新的线性组合,这些组合可以提高定位精度与定位速度.%The third carrier will be provided by modernized GLONASS satellites frequency program. With the GLONASS carrier phase observation model as a prerequisite, three frequency carrier phase combination of GLONASS method was researched. The effects of ionospheric delay and observation noise on the observations combined from three frequency were analyzed. According to long wavelength standard, weak ionospheric delay standards, weak observation noise standards, some useful linear combination was put forward to improve the positioning accuracy and speed.

  15. High-Frequency Link Inverter for Fuel Cells Based on Multiple-Carrier PWM (to continue)

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    C. Operation of a PWM Cycloconverter The concepts in Section Ⅱ-B, present a progression of solutions to known design difficulties. To incorporate these benefits and eliminate the redundant conversion step shown in Fig. 6, we propose the PWM cycloconverter shown in Fig. 7. It will be shown in Section Ⅲ. that the conventional PWM inverter can be unified through a multiple-carrier PWM framework. The control concept introduced is extended to demonstrate that multiple-carrier PWM methods lead to HF link inverters that are nearly as simple to control as conventional PWM inverters.

  16. 基于中心频率检测的应答机载波捕获技术%Transponder carrier acquisition technique based on center frequency detection

    Institute of Scientific and Technical Information of China (English)

    张朝杰; 金小军; 姜建文; 金仲和

    2011-01-01

    In the condition of second order phase locked loop using perfect integrator loop filter, the loop center frequency drifts in response to thermal noise when no useful input signal presents. To avoid the problem of loop center frequency drift, the satellite on board transponder's carrier acquisition technique was studied. On the basis of all digital carrier recovery loop receiver architecture using I/Q sub-sampling technique, a center frequency detector was used to control the loop. This architectural solution allows to close the carrier recovery loop only when the uplink carrier signal is detected by the center frequency detector, thus avoiding the drift of center frequency in response to thermal noise at the receiver input. The design method of center frequency detector was given, and the relationship between the probability of missed detection and the probability of false alarm was analyzed. The detector parameter selection was given based on the result of analysis.%针对基于理想型积分环路滤波器的二阶锁相环在无信号输入时,环路中心频率会随热噪声发生漂移的问题,研究了卫星星载测控应答机的载波捕获技术.为解决无信号输入下的环路中心频率漂移问题,在基于正交欠采样技术及全数字载波恢复环的接收机结构基础上,通过一级中心频率检测器控制环路.当检测到上行信号时闭合环路,避免了接收机中心频率在无信号输入时随热噪声发生漂移.给出了中心频率检测器的设计方法,分析了检测器漏检概率和误判概率之间的关系,并在此基础上给出了检测器的具体参数选择依据.

  17. On a simple attack, limiting the range transmission of secret keys in a system of quantum cryptography based on coding in a sub-carrier frequency

    Science.gov (United States)

    Klimov, A. N.; Kulik, S. P.; Molotkov, S. N.; Potapova, T. A.

    2017-03-01

    In the paper by Gleim et al (2016 Opt. Express 24 2619), it was declared that the system of quantum cryptography, exploiting quantum key distribution (QKD) protocol BB84 with the additional reference state and encoding in a sub-carrier, is able to distribute secret keys at a distance of 210 km. The following shows that a simple attack realized with a beam splitter results in a loss of privacy of the keys over substantially smaller distances. It turns out that the actual length of the secret key transmission for the QKD system encoding in the sub-carrier frequency is ten times less than that declared in Gleim et al (2016 Opt. Express 24 2619). Therefore it is impossible to safely use the keys when distributed at a larger length of the communication channel than shown below. The maximum communication distance does not exceed 22 km, even in the most optimistic scenario.

  18. Analysis and modeling of low voltage electrical network at power line carrier frequencies (3-148.5 kHz); Analyse et modelisation du reseau basse tension aux frequences courants porteurs (3 KHZ-148,5 KHZ)

    Energy Technology Data Exchange (ETDEWEB)

    Duval, G.

    1998-07-01

    Electricite de France (EdF) wishes to establish a physical communication link between his clients and the EdF centres. The final link, i.e. between the high/low voltage transformation substation and the residential clients, being ensured by carrier currents. With this aim, an analysis and a modeling of the low voltage network at the carrier frequencies (3 kHz - 148.5 kHz) has been performed. This work has been carried out in parallel with an experiment involving 3500 apparatuses that use carrier currents. The diversity of the French low voltage networks and the limitations imposed by the EN50065-1 standard about the use of carrier currents in Europe do not favour the development of such carrier current systems. Disturbing voltages and localized impedances represent the main difficulties to get round. Inside accommodations, domotic carrier currents have a reduced range but a higher disturbance amplitude because of the proximity of appliances. A differential mode to common mode conversion phenomenon has been evidenced which generates network couplings and important electromagnetic fields. Energy lines and cables have been analyzed using numerical models. Load peaks have been analyzed using statistical tools in order to take into account the daily fluctuations. The modeling of the network is made in two steps: a double-wire model is considered first. Then a three-phase model is developed which analyzes the inter-phases coupling and the effect of the distribution of clients' loads on each phase. The results of this model are conformable with measurements except for underground networks. As perspectives of future works and beyond todays standard framework, the techniques that allow a sensible increase of communication flow rates have been reviewed. (J.S.)

  19. Modeling of sheet carrier density and microwave frequency characteristics in Spacer based AlGaN/AlN/GaN HEMT devices

    Science.gov (United States)

    Mohanbabu, A.; Anbuselvan, N.; Mohankumar, N.; Godwinraj, D.; Sarkar, C. K.

    2014-01-01

    In this paper, we present a physics-based model for two-dimensional electron gas (2DEG) sheet carrier density ns and various microwave characteristics such as transconductance, cut-off frequency (ft) of the proposed Spacer layer based AlxGa1-xN/AlN/GaN High Electron Mobility Transistors (HEMTs) is modeled by considering the quasi-triangular quantum well. To obtain charge density ns, the variation of Fermi level with supply voltage and the formation of various energy sub-bands E0, E1 are considered. The obtained results are simple and easy to analyze the sheet carrier density, DC model and microwave frequency performance analysis for nanoscale Spacer layer based AlxGa1-xN/AlN/GaN HEMT power devices. The Spacer layer based AlGaN/AlN/GaN heterostructure HEMTs shows excellent promise as one of the candidates to substitute present AlGaN/GaN HEMTs for future high speed and high power applications. Derived model results for drain current, transconductance, current-gain cutoff frequency for different short and long gate length device are calibrated and verified with experimental data over a full range for gate and drain applied voltages and is useful for nanoscale and microwave analysis for circuit design.

  20. Higher frequency of certain cancers in LRRK2 G2019S mutation carriers with Parkinson disease: a pooled analysis.

    Science.gov (United States)

    Agalliu, Ilir; San Luciano, Marta; Mirelman, Anat; Giladi, Nir; Waro, Bjorg; Aasly, Jan; Inzelberg, Rivka; Hassin-Baer, Sharon; Friedman, Eitan; Ruiz-Martinez, Javier; Marti-Masso, Jose Felix; Orr-Urtreger, Avi; Bressman, Susan; Saunders-Pullman, Rachel

    2015-01-01

    Patients with Parkinson disease (PD) who harbor LRRK2 G2019S mutations may have increased risks of nonskin cancers. However, the results have been inconsistent across studies. To analyze pooled data from 5 centers to further examine the association between LRRK2 G2019S mutation and cancer among patients with PD and to explore factors that could explain discrepancies. Clinical, demographic, and genotyping data as well as cancer outcomes were pooled from 1549 patients with PD recruited across 5 movement disorders clinics located in Europe, Israel, and the United States. Associations between LRRK2 G2019S mutation and the outcomes were examined using mixed-effects logistic regression models to estimate odds ratios (ORs) and 95% CIs. Models were adjusted for age and ethnicity (Ashkenazi Jewish vs others) as fixed effects and study center as a random effect. All cancers combined, nonskin cancers, smoking-related cancers, hormone-related cancers, and other types of cancer. The overall prevalence of the LRRK2 G2019S mutation was 11.4% among all patients with PD. Mutation carriers were younger at PD diagnosis and more likely to be women (53.1%) and of Ashkenazi Jewish descent (76.8%) in comparison with individuals who were not mutation carriers. The LRRK2 G2019S mutation carriers had statistically significant increased risks for nonskin cancers (OR, 1.62; 95% CI, 1.04-2.52), hormone-related cancers (OR, 1.87; 95% CI, 1.07-3.26) and breast cancer (OR, 2.34; 95% CI, 1.05-5.22) in comparison with noncarriers. There were no associations with other cancers. There were no major statistically significant differences in the results when the data were stratified by Ashkenazi Jewish ethnicity; however, there was some evidence of heterogeneity across centers. This multinational study from 5 centers demonstrates that LRRK2 G2019S mutation carriers have an overall increased risk of cancer, especially for hormone-related cancer and breast cancer in women. Larger prospective cohorts or

  1. Block Iterative/Adaptive Frequency-Domain Channel Estimation for Cyclic-Prefixed Single-Carrier Broadband Wireless Systems

    Directory of Open Access Journals (Sweden)

    Jong-Seob Baek

    2008-01-01

    Full Text Available This paper presents a new block iterative/adaptive frequency-domain channel estimation scheme, in which a channel frequency response (CFR is estimated iteratively by the proposed weighted element-wise block adaptive frequency-domain channel estimation (WEB-CE scheme using the soft information obtained by a soft-input soft-output (SISO decoder. In the WEB-CE, an equalizer coefficient is calculated by minimizing a weighted conditional squared-norm of the a posteriori error vector with respect to its correction term. Simulation results verify the superiority of the WEB-CE in a time-varying typical urban (TU channel.

  2. Spectrum of genetic changes in patients with non-syndromic hearing impairment and extremely high carrier frequency of 35delG GJB2 mutation in Belarus.

    Science.gov (United States)

    Danilenko, Nina; Merkulava, Elena; Siniauskaya, Marina; Olejnik, Olga; Levaya-Smaliak, Anastasia; Kushniarevich, Alena; Shymkevich, Andrey; Davydenko, Oleg

    2012-01-01

    The genetic nature of sensorineural hearing loss (SNHL) has so far been studied for many ethnic groups in various parts of the world. The single-nucleotide guanine deletion (35delG) of the GJB2 gene coding for connexin 26 was shown to be the main genetic cause of autosomal recessive deafness among Europeans. Here we present the results of the first study of GJB2 and three mitochondrial mutations among two groups of Belarusian inhabitants: native people with normal hearing (757 persons) and 391 young patients with non-syndromic SNHL. We have found an extremely high carrier frequency of 35delG GJB2 mutation in Belarus -5.7%. This point deletion has also been detected in 53% of the patients with SNHL. The 312del14 GJB2 was the second most common mutation in the Belarus patient cohort. Mitochondrial A1555G mt-RNR1 substitution was found in two SNHL patients (0.55%) but none were found in the population cohort. No individuals carried the A7445G mutation of mitochondrial mt-TS1. G7444A as well as T961G substitutions were detected in mitochondrial mt-RNR1 at a rate of about 1% both in the patient and population cohorts. A possible reason for Belarusians having the highest mutation carrier frequency in Europe 35delG is discussed.

  3. Prolonged response to calling songs by the L3 auditory interneuron in female crickets (Acheta domesticus): possible roles in regulating phonotactic threshold and selectiveness for call carrier frequency.

    Science.gov (United States)

    Bronsert, Michael; Bingol, Hilary; Atkins, Gordon; Stout, John

    2003-03-01

    L3, an auditory interneuron in the prothoracic ganglion of female crickets (Acheta domesticus) exhibited two kinds of responses to models of the male's calling song (CS): a previously described, phasically encoded immediate response; a more tonically encoded prolonged response. The onset of the prolonged response required 3-8 sec of stimulation to reach its maximum spiking rate and 6-20 sec to decay once the calling song ceased. It did not encode the syllables of the chirp. The prolonged response was sharply selective for the 4-5 kHz carrier frequency of the male's calling songs and its threshold tuning matched the threshold tuning of phonotaxis, while the immediate response of the same neuron was broadly tuned to a wide range of carrier frequencies. The thresholds for the prolonged response covaried with the changing phonotactic thresholds of 2- and 5-day-old females. Treatment of females with juvenile hormone reduced the thresholds for both phonotaxis and the prolonged response by equivalent amounts. Of the 3 types of responses to CSs provided by the ascending L1 and L3 auditory interneurons, the threshold for L3's prolonged response, on average, best matched the same females phonotactic threshold. The prolonged response was stimulated by inputs from both ears while L3's immediate response was driven only from its axon-ipsilateral ear. The prolonged response was not selective for either the CS's syllable period or chirp rate.

  4. Research on Feature Extraction of Composite Pseudocode Phase Modulation-Carrier Frequency Modulation Signal Based on PWD Transform

    Institute of Scientific and Technical Information of China (English)

    LI Ming-zi; ZHAO Hui-chang

    2008-01-01

    The identification features of composite pseudocode phase modulation and carry frequency modulation signal in-clude pseudocode and modulation frequency. In this paper, PWD is used to extract these features. First, the feature of pseudocode is extracted using the amplitude output of PWD and the correlation filter technology. Then the feature of fre-quency modulation is extracted by way of PWD analysis on the signal processed by anti-phase operation according to the extracted feature of pseudo code, i.e. position information of changed abruptly point of phase. The simulation result shows that both the features of frequency modulation and phase change position caused by the pseudocode phase modula-tion can be extracted effectively for SNR = 3 dB.

  5. Cavity-enhanced optical Hall effect in two-dimensional free charge carrier gases detected at terahertz frequencies.

    Science.gov (United States)

    Knight, S; Schöche, S; Darakchieva, V; Kühne, P; Carlin, J-F; Grandjean, N; Herzinger, C M; Schubert, M; Hofmann, T

    2015-06-15

    The effect of a tunable, externally coupled Fabry-Perot cavity to resonantly enhance the optical Hall effect signatures at terahertz frequencies produced by a traditional Drude-like two-dimensional electron gas is shown and discussed in this Letter. As a result, the detection of optical Hall effect signatures at conveniently obtainable magnetic fields, for example, by neodymium permanent magnets, is demonstrated. An AlInN/GaN-based high-electron mobility transistor structure grown on a sapphire substrate is used for the experiment. The optical Hall effect signatures and their dispersions, which are governed by the frequency and the reflectance minima and maxima of the externally coupled Fabry-Perot cavity, are presented and discussed. Tuning the externally coupled Fabry-Perot cavity strongly modifies the optical Hall effect signatures, which provides a new degree of freedom for optical Hall effect experiments in addition to frequency, angle of incidence, and magnetic field direction and strength.

  6. Tunable, Low Frequency Microwave Generation from AWG Based Closely-Spaced Dual-Wavelength Single Longitudinal-Mode Fibre Laser

    Science.gov (United States)

    Ahmad, H.; Latif, A. A.; Talib, J. M.; Harun, S. W.

    2013-06-01

    Stable, closely-spaced Dual-Wavelength Fibre Lasers (DWFLs) have high potential for applications such as Radio-over-Fibre and optical sensing. In this work, a DWFL using two Arrayed Waveguide Gratings (AWGs) to generate a closely-spaced dual-wavelength output is proposed and demonstrated. A 1 m long highly doped Leikki Er80-8/125 Erbium Doped Fibre (EDF) is used as the linear gain medium, while two AWGs are used to generate the closely-spaced lasing wavelengths. A Mach-Zehnder modulator, driven at 180 kHz, splits the closely spaced wavelengths into two clearly defined wavelengths, while a 7 cm long un-pumped Leikki Er80-8/125 EDF and sub-ring cavity is used to suppress unwanted side-modes. Close spacing of between 0.01 to 0.03 nm are obtained, with beating frequencies of between 1.4 to 3.2 GHz. The output is highly stable, with almost no fluctuations over the test period.

  7. Differential carrier lifetime in InGaN-based light-emitting diodes obtained by small-signal frequency-domain measurements

    Science.gov (United States)

    Reklaitis, I.; Nippert, F.; Kudžma, R.; Malinauskas, T.; Karpov, S.; Pietzonka, I.; Lugauer, H. J.; Strassburg, M.; Vitta, P.; TomašiÅ«nas, R.; Hoffmann, A.

    2017-01-01

    Recently, a novel method for evaluation of recombination coefficients corresponding to Shockley-Read-Hall, radiative, and Auger recombination channels has been proposed, which combines measurements of the light emitting diode (LED) external quantum efficiency under continuous wave operation with the determination of non-equilibrium carrier differential life time (DLT) by small-signal time-resolved photoluminescence [Nippert et al., Jpn. J. Appl. Phys., Part 1 55, 05FJ01 (2016)]. In this work, we suggest an alternative technique, small-signal frequency-domain lifetime measurements, which is implemented more easily and capable of operating in a wider range of LED operating currents. The DLTs measured by both techniques are shown to agree well with each other, but saturate at low currents, contrary to the trend predicted by the well-known ABC-model. We discuss possible reasons for this deviation, as well as advantages and limitations of the measurement techniques.

  8. Low Frequency Noise Degradation in 45 nm High-k nMOSFETs due to Hot Carrier and Constant Voltage Stress

    Science.gov (United States)

    Rahman, M. Shahriar; ćelik-Butler, Zeynep; Quevedo-Lopez, M. A.; Shanware, Ajit; Colombo, Luigi

    2009-04-01

    Hafnium based materials are the leading candidates to replace conventional SiON as the gate dielectric in complementary metal-oxide-semiconductor devices. Hot carrier and constant voltage stress induced 1/f noise behavior is presented for HfSiON nMOSFETs. The additional low-frequency noise introduced through stressing was evaluated on nMOSFETs with TiN metal gate and HfSiON gate dielectric. Nitridation of HfSiO was achieved either by high temperature thermal nitridation or by relatively lower temperature plasma nitridation. The difference in stress induced noise behavior is attributed to the nitrogen profile across high-k/Si interface and bulk of high-k gate oxide caused by different nitridation techniques.

  9. Performance Analysis of the Low-Complexity Adaptive Channel Estimation over Non-Stationary Multipath Rayleigh Fading Channels Under Carrier Frequency Offsets

    CERN Document Server

    Hadei, Sayed A

    2011-01-01

    This paper provides analytical performance of the low-complexity family of affine projection algorithms on the estimation of multipath Rayleigh fading channels in the presence of carrier frequency offsets (CFO) and random channel variations. Our analysis is based on the calculation of the error correlation matrix of the estimation, the mean-square weight error (MSWE) and the mean-square estimation error (MSE) parameters. The analysis does not use strong assumptions like small or large step-size, and explicit closed-form expressions for the MSE of estimation are obtained only from common hypotheses in wireless communication context. In this paper, the optimum stepsize parameters minimizing the MSE of estimation are analytically derived without any simplified assumptions. For the sake of comparison with other analytical approaches, we also investigate the performance of the introduced algorithms by the energy conservation relation. Likewise for exact performance analysis, we evaluate all the moment terms that a...

  10. The frequency of Neisseria gonorrhoeae endocervical infection among female carrier and changing trends of antimicrobial susceptibility patterns in Kashan, Iran.

    Directory of Open Access Journals (Sweden)

    Shima Afrasiabi

    2014-06-01

    Full Text Available Neisseria gonorrhoeae is the second most sexually transmitted diseases agents in developing countries. Antimicrobial resistance strains have created serious health concern. The aim of this study was to determine the frequency of endocervical gonococcal infection and antimicrobial susceptibility of N. gonorrhoeae in Kashan, Iran.In this study, 294 endocervical swabs were collected from married women referred to the obstetrics and gynecology clinics in Kashan from December 2012 to May 2013. The samples were cultured in modified Thayer Martin in 37°C with 5-10% CO2 for 72 hours. Gram staining, oxidase, catalase and carbohydrate utilization tests were used to identify the isolated species. All isolates were tested for their susceptibilities to antimicrobials using the Kirby Bauer-disk diffusion techniques.N. gonorrhoeae was detected in 2.38% of studied cases (95% confidence interval [CI] 1.5-3.26%. All isolates were resistance to ceftriaxone, penicillin G, ciprofloxacin, cefepime, and two isolate (28.5% showed intermediate sensitivity to tetracycline.Continued monitoring of prevalence of N. gonorrhoeae is important for preventing the dissemination of this microorganism. The present study emphasizes the importance of surveillance of antimicrobial resistance of N. gonorrhoeae in order to manage the rate of resistant strains and to revise the treatment policies.

  11. 同频混合信号参数联合最大似然递归估计%Joint ML Iterative Estimation of Carrier Frequency, Phase, Channel for Co-Frequency Signals

    Institute of Scientific and Technical Information of China (English)

    瞿孟虹; 何晓霜; 游凌

    2015-01-01

    In order to improve the accuracy and simplify the produces of parameters estimation in paired carrier multiple access (PCMA), this paper proposes an algorithm of joint iterative estimation of carrier frequency, phase, and channel. Basing on maximum likelihood (ML) criterion, the joint estimator using data-aided technique is derived and the iterative resolution is given. The quantitative analysis of the joint estimator characteristics indicates that the accuracy the joint estimator almost achieves the Cramer-Rao bound (CRB), and therefore the algorithm fits for frequency selective channels. Computer simulation results show the validity of the algorithm.%为提高成对载波多址(PCMA)模式下参数估计精度,简化实现流程,提出一种混合信号条件下频偏、相偏、信道联合估计算法。该算法基于最大似然准则,利用数据辅助技术,推导出联合参数估计显性表达式,并给出递归求解方法。对该算法估计性能进行的定量分析表明,估计性能逼近混合信号条件下克拉美罗界(Cramer-Rao bound),能适应频率选择性信道。计算机仿真结果验证了该算法的有效性。

  12. A novel research approach on the dynamic properties of photogenerated charge carriers at Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films by a frequency-modulated surface photovoltage technology

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu; Zhang, Wei [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Xie, Tengfeng; Wang, Dejun [College of Chemistry, Jilin University, Changchun 130012 (China); Song, Xi-Ming, E-mail: songlab@lnu.edu.cn [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China)

    2013-09-01

    Graphical abstract: The changed SPV with chopping frequencies indicate the separation speeds of photogenerated charge carriers in different films. - Highlights: • Ag{sub 2}S-sensitized TiO{sub 2} films show good photoelectric responses in visible-light region. • Frequency-modulated SPV give dynamic information and evidence of Ag{sub 2}S QDSSCs’ performance. • Frequency-modulated SPV can supply complementary information in the study of Ag{sub 2}S ODSSCs. - Abstract: Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films with different amount of Ag{sub 2}S were fabricated by a successive ionic layer adsorption and reaction (SILAR) method. The separation and transport of photogenerated charge carriers at different spectral regions were studied by the frequency-modulated surface photovoltage technology. Some novel dynamic information of photogenerated charge carriers in a wide spectral range is found. The results indicate that the rate and direction of separation (diffusion) for photogenerated charge carriers are closely related to the performance of quantum-dots-sensitized solar cells (QDSSCs) based on the Ag{sub 2}S/TiO{sub 2} nano-structure.

  13. The performance of GPS time and frequency transfer: comment on ‘A detailed comparison of two continuous GPS carrier-phase time transfer techniques’

    Science.gov (United States)

    Petit, Gérard; Defraigne, Pascale

    2016-06-01

    The paper ‘A detailed comparison of two continuous GPS carrier-phase time transfer techniques’ (Yao et al 2015 Metrologia 52 666) presents the revised RINEX-shift (RRS) method, a technique using ‘classical precise point positioning (PPP)’ solutions on sliding batches and aiming at providing continuous time links. The authors claim the superiority of the RRS technique with respect to ‘classical PPP’ in terms of frequency stability and solving for discontinuities due to data gaps. It is shown here that these conclusions do not rely on physical principles, and are erroneous as they are driven by misinterpreted or corrupted PPP solutions. Using state-of-the-art PPP computation on the same data sets used in Yao et al’s paper (2015 Metrologia 52 666), we show that the stability of RRS is at best similar to that of ‘classical PPP’ (within statistical uncertainties). Furthermore, the RRS method of removing discontinuities in case of data gaps by interpolating the phase data should not be applied systematically as it can cause erroneous clock solutions when the data gaps are associated with a true phase discontinuity.

  14. Asymmetric Carrier Random PWM

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Lungeanu, Florin; Rasmussen, Peter Omand;

    2010-01-01

    This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on the measurements, it is shown that the spread effect of the discrete components from the motor current spectra is very effective independent of the modulation...... index. The flat motor current spectrum generates an acoustical noise close to the white noise, which may improve the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in open, as well...

  15. Aircraft Carriers

    DEFF Research Database (Denmark)

    Nødskov, Kim; Kværnø, Ole

    There are many indications that China is actively researching the design of an aircraft carrier. It is unknown whether China will initiate the actual acquisition of a carrier, but the indications that are available of their research into aircraft carriers and carrier-capable aircraft, as well...... as their purchases of aircraft carrier systems, makes it more than likely that the country is preparing such an acquisition. China has territorial disputes in the South China Sea over the Spratly Islands and is also worried about the security of its sea lines of communications, by which China transports the majority...... of its foreign trade, as well as its oil imports, upon which the country is totally dependent. China therefore has good reasons for acquiring an aircraft carrier to enable it to protect its national interests. An aircraft carrier would also be a prominent symbol of China’s future status as a great power...

  16. Low frequency of mutations in the core promoter and precore regions of hepatitis B virus in anti-HBe positive Brazilian carriers

    Directory of Open Access Journals (Sweden)

    Niel Christian

    2001-07-01

    Full Text Available Abstract Background Mutations in the core promoter and precore regions of the hepatitis B virus (HBV genome, notably the double substitution (AGG to TGA at nt positions 1762-1764 in the core promoter, and the precore stop codon mutation G to A at nt 1896, can often explain the anti-HBe phenotype in chronic carriers. However, the A1896 mutation is restricted to HBV isolates that have T at nt 1858. The double substitution at positions 1762-1764 has been described to occur preferentially in patients infected with strains showing C instead of T at nt 1858. Results HBV DNAs from 29 anti-HBe Brazilian samples were characterized by nucleotide sequencing of PCR products from precore region. Among them, 18 isolates presented C at nt 1858 (mostly genotype A strains. The 11 remaining isolates (genotypes D and F had T1858. The stop codon mutation at nt 1896 was found in seven isolates (24% of the total and 63% of the isolates that had T1858. The frequency of the double substitution at positions 1762-1764 was surprisingly low (20% among C1858 isolates. An association between A1896 and TGA 1762-1764 mutations was observed among genotype D isolates: these showed either none of the two mutations or both. Furthermore, strains mutated at positions 1896 and/or 1762-1764 also presented an elevated number of other, less common substitutions in the core promoter and precore regions. Conclusions The data reported here are not in accordance with some reports from other parts of the world. In half of the isolates, none of the mutations previously described could explain the anti-HBe phenotype.

  17. An Automatic Meter Reading System Based on Integrated Carrier and Power Frequency Technology%基于载波和工频混合组网技术的集中抄表系统

    Institute of Scientific and Technical Information of China (English)

    王智慧; 李建歧; 渠晓峰; 赵涛

    2011-01-01

    低压电力线载波信道的衰减、干扰以及随机时变性使得载波通信方式无法满足集中抄表系统全采集、全覆盖的建设要求.工频通信也是通过电力线传输信号,并使用50Hz工频信号作为载波,与3~500kHz的载波通信频率范围互不冲突.本文利用工频通信传输距离远、可靠性高、成本低廉的特点,在不增加额外设备的条件下,实现了载波与工频两种通信方式的混合组网.针对所给出的组网方案,详细论述了集中器和采集器的系统实现.现场测试表明,该系统抄收成功率高、通信效果好,有效解决了载波通信盲点问题.%Low- voltage power line carrier channel attenuation, interference and random dynamicity make the carrier communication can not satisfy automatic meter reading system whole collection and coverage construction requirements.TWACS also transmits signal by power line, and uses the 50Hz power frequency signal as its carrier frequency, which is not conflictive with the 3 ~ 500kHz carrier communication frequency range. Based on the long transmission distance,high communication reliability and low cost of TWACS, this paper realizes a mixing network composed of carrier and power frequency communication without any additional equipment. Then the system implementation of concentrator and acquisition terminal is discussed, aiming at the given networking scheme. The field test proved that the system effectively solves the carrier communication blind spot problem, with high reading success rate and good communication effect.

  18. Autonomous component carrier selection

    DEFF Research Database (Denmark)

    Garcia, Luis Guilherme Uzeda; Pedersen, Klaus; Mogensen, Preben

    2009-01-01

    in local areas, basing our study case on LTE-Advanced. We present extensive network simulation results to demonstrate that a simple and robust interference management scheme, called autonomous component carrier selection allows each cell to select the most attractive frequency configuration; improving...

  19. Research on LTE Carrier Aggregation with Compression Bandwidth and Sharing Frequency Application Between LTE and GSM%LTE压缩带宽载波聚合及与GSM频谱共享方案研究

    Institute of Scientific and Technical Information of China (English)

    王伟; 荣耀; 聂昌

    2016-01-01

    It proposes a scheme on the LTE carrier aggregation with compression bandwidth and sharing frequency between LTE and GSM. It realizes 20+10 MHz LTE carrier aggregation and GSM single frequency network with 12 carriers in 30 MHz bandwidth. The results of field test show that performance of the network is not lost by the compression bandwidth carrier aggregation. Moreover,there is little interference between LTE and GSM when co-location of their sites. LTE BS is interfered by GSM UE when co-existence of their sites. So,it is suggested that the proposed scheme can be implemented in co-location,or avoid using GSM carriers in the LTE bandwidth when co-existence.%提出了一种LTE压缩带宽载波聚合及与GSM频率共享的频率使用方案。在30 MHz带宽内实现20+10 MHz LTE载波聚合以及具有12个GSM频点的单频GSM网络。并通过实测的方式对该方案进行了网络性能验证。结果表明压缩带宽载波聚合在网络性能上基本没有损失。GSM与LTE在共站场景下,相互之间干扰甚微,可实现共存。在不共站场景下GSM终端对LTE基站存在干扰。建议该方案在共站场景下实施或避免在不共站场景下使用LTE带内的频点。

  20. Carrier Frequency Intelligent Power-Saving Technology Application in Td-Scdma LTE Communication Network%载频智能节电技术在TD-LTE通信网络中的应用

    Institute of Scientific and Technical Information of China (English)

    唐文良

    2015-01-01

    现今TD-LTE通信网络在人们身边无处不在,如中国移动联通等.基站的能耗在移动通信网络中占了一半以上.因此针对耗能这方面我们提出了载频智能节电技术.载频智能节电技术可达到节能减排的效果.文中先是介绍节能的意义以及为什么节能.然后我们了解具体载频基站的组成部分以及功耗比例.关断节能技术的原理以及实施方案,接着从各方面条件因素来完善智能节能技术.不同场景不同时段需要的功耗来制定不同的方案.对比不同的节能技术需要的条件因数以及外在的因数来评论载频智能节电技术.在这之前GSM系统中,就有从GSM网络的方面考虑,根据各方面的因数来考虑提出了两个各节能方法,其一是针对基站主设备其二是载频关断节能技术.根据TD-LTE系统基站主设备的运行原理来分析载频关断节能技术在基站系统中的实用性以及节能性.全方面的剖析载频智能节电技术在通信网络应用中意义.%nowadays the td-scdma LTE communication network in people around everywhere, such as China mobile, unicom, etc. The energy consumption of the base station in mobile communication network in the accounts for more than half. So for the con-sumption ways we carrier frequency intelligent power saving technology were put forward. Carrier frequency intelligent power sav-ing technology can achieve the effect of energy conservation and emissions reduction. Why in this paper, we first introduce the sig-nificance of energy saving and energy saving. Then we can know the specific carrier frequency part of base station and the power consumption ratio. Shut off the principle of energy saving technology and implementation plan, then factors from various aspects condition to improve the intelligent energy-saving technologies. Different at different times the power consumption of the need to develop different scenarios. Comparison of different energy saving

  1. SIMO信道下MPSK信号载波频率及相位联合估计%Joint Carrier frequencies and Phases Estimation for MPSK Signals over SIMO channels

    Institute of Scientific and Technical Information of China (English)

    杨珂; 于宏毅; 李鸥; 高吉

    2011-01-01

    To improve the estimation performance at low SNR, a joint blind estimator of carrier frequencies and phases for MPSK signals over single input multiple output (SIMO) channels is proposed. As the received signals in SIMO channels have the same data symbols, the proposed algorithm constructs several single tone signals by multiplying the received signals with different combinations, the carrier frequencies and phases of which are linear combination with that of the received signals. By estimation the carrier parameter of these single tone signals, overdetermined equations with the interested parameters are established. After removing the outlier data probably existed in the estimations of parameters of single tone signals, the carrier frequencies and phases estimation of MPSK over SIMO channels can be obtained by weighted least square methods. Simulations show that the proposed estimator improves the performance of carrier frequencies and phases estimation especially at low SNR levels and have a lower SNR threshold than estimators traditionally u-sing only one receive antenna.%为了提高低信噪比条件下MPSK信号载波参数的估计性能,提出了一种基于SIMO信道的MPSK信号载波频率与相位联合盲估计算法.该算法充分利用SIMO信道下多个接收信号间承载相同信息序列的特点,首先通过接收信号的不同组合构造多种乘积序列形成多个单音信号;通过对单音信号载波参数的估计,获得关于待估参数的超定方程组;然后利用最小二乘方法剔除单音信号参数估计中可能存在的“野值”点;最后,通过加权最小二乘解算实现对SIMO信道下MPSK信号载波频率与相位联合估计.仿真结果表明,与传统的单天线参数估计算法相比,在观测时间相同的条件下,本文算法在低信噪比条件下具有更加精确的参数估计性能;同时,频率估计“野值”现象出现的信噪比门限也较传统单天线方法显著下降.

  2. Carrier synchronization for STBC OFDM systems

    Institute of Scientific and Technical Information of China (English)

    Cai Jueping; Song Wentao; Li Zan; Ge Jianhua

    2005-01-01

    All-digital carrier synchronization strategies and algorithms for space-time block coding (STBC) orthogonal frequency division multiplexing (OFDM) are proposed in this paper. In our scheme, the continuous pilots (CP) are saved, and the complexity of carrier synchronization is reduced significantly by dividing the process into three steps. The coarse carrier synchronization and the fine carrier synchronization algorithms are investigated and analyzed in detail. Simulations show that the carrier can be locked into tracking mode quickly, and the residual frequency error satisfies the system requirement in both stationary and mobile environments.

  3. 残留频偏下LDPC-MSK系统码辅助载波同步算法%Code-aided carrier synchronization for LDPC-MSK systems in presence of residual frequency offset

    Institute of Scientific and Technical Information of China (English)

    赵旦峰; 周相超; 钱晋希; 付芳

    2012-01-01

    Regarding the carrier synchronization difficulty of low density parity check code-minimum shift keying (LDPC-MSK) systems existed at low signal-to-noise ratios (SNR), a new code-aided carrier synchronization algorithm is proposed. The soft decoding information is utilized to coarse synchronization based on cost function and fine synchronization based on maximum likelihood (ML) criterion. The reliable carrier synchronization is achieved by conducting the joint iteration of synchronizer, demodulator and decoder. Both the theoretical studies and the simulation results show that, at the low SNR, the efficient carrier synchronization can be achieved with large frequency and phase offset. Almost ideal performance is obtained with rather low system complexity.%针对低信噪比条件下低密度奇偶校验码-最小频移键控系统载波同步实现困难的问题,提出了一种新的码辅助载波同步算法.该算法将译码软信息分别运用到基于代价函数的载波粗同步和基于最大似然迭代的载波细同步之中,将同步器、解调器与译码器联合迭代,从而实现较理想的载波同步.理论研究和仿真结果表明,在低信噪比条件下,该算法能够在大频偏、大相偏范围内实现有效的载波同步,并以较低系统复杂度的代价,获得近似理想的系统性能.

  4. Analysis of the Effect of Carrier Frequency Offset on the Performance of Transform Domain Communication System%载波频率偏差对变换域通信系统性能的影响分析

    Institute of Scientific and Technical Information of China (English)

    王舒; 达新宇; 褚振勇; 谢铁城; 邹维

    2012-01-01

    Considering the situation that the received signals magnitude is decreased and inter-carrier interference (ICI) is induced by the carrier frequency offsets (CFO) , through establishing mathematical model, the analytical expression for the Bit Error Rate (BER) , which is derived from Transform Domain communication system (TDCS) , is obtained. Furthermore, the relationships between the BER and the correlated parameters are studied, as well as, the Signal Noise Ratio (SNR) loss. Finally, the analysis conclusions are verified by the simulation, the simulation result agrees well with the analysis conclusion. The quantitative analysis of the system performance caused by the frequency error of carrier is given. These researches illustrate that the frequency offset affect the BER performance seriously and there is error floor on the BER when the normalized frequency offset is more than 0. 6. To keep the system work around, the normalized frequency offset has to be less than 0. 05.%针对载波频率偏差导致变换域通信系统的接收信号幅度下降并产生载波间干扰的问题,通过建立系统模型,推导出了载波频偏存在情况下系统误码率的解析式,在此基础上,分析了子载波个数、频谱使用率以及载波频偏与系统输出信噪比的关系,以信噪比损失为度量,定量地给出了载波频偏对系统性能的影响,最后进行了仿真验证,仿真结果与数值分析高度吻合.仿真结果表明:频偏显著影响系统性能,且归一化载波频偏大于0.6时与误码率之间会出现地板效应;为避免系统性能恶化,归一化频偏应控制在0.05的范围内.

  5. A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP for a Single Frequency Global Position System (GPS + BeiDou Navigation Satellite System (BDS Receiver

    Directory of Open Access Journals (Sweden)

    Chuang Qian

    2016-12-01

    Full Text Available As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS + BeiDou Navigation Satellite System (BDS is proposed. The method uses a Time-differenced Carrier Phase (TDCP model, which eliminates the Inner-System Bias (ISB between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

  6. A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP) for a Single Frequency Global Position System (GPS) + BeiDou Navigation Satellite System (BDS) Receiver.

    Science.gov (United States)

    Qian, Chuang; Liu, Hui; Zhang, Ming; Shu, Bao; Xu, Longwei; Zhang, Rufei

    2016-12-05

    As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS) + BeiDou Navigation Satellite System (BDS) is proposed. The method uses a Time-differenced Carrier Phase (TDCP) model, which eliminates the Inner-System Bias (ISB) between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM) to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

  7. A Low-Frequency Tone Sweep Method for in-Service Fault Location in Sub-Carrier Multiplexed Optical Fiber Networks

    CERN Document Server

    Amaral, Gustavo C; Baldivieso, Andrea; Garcia, Joaquim Dias; Leibel, Renata G; Herrera, Luis E Y; Urban, Patryk J; von der Weid, Jean Pierre

    2016-01-01

    We demonstrate an optical fiber fault location method based on the frequency response of the modulated fiber optical backscattered signal in a steady state low-frequency step regime. Careful calibration and measurement allows for the reconstruction of the fiber transfer function, which, associated to its mathematical model, is capable of extracting the fiber characteristics. The technique is capable of identifying non-reflective fault events in an optical fiber link and is perfectly compatible with previous methods that focus on the reflective events. The fact that the recuperation of the complex signal is performed in the frequency domain and not via a Fourier Transform enables the measurements to overcome the spatial resolution limitation of Fourier Transform incoherent-OFDR measurements even with frequency sweep ranges down to 100-100000 Hz. This result is backed up by a less than 10 meters difference in fault location when compared to standard OTDR measurements.

  8. 对线性调频脉冲压缩雷达的多载波调制转发干扰%Multi-carrier Modulation Repeater Jamming against Linear Frequency Modulated Pulse-compression Radar

    Institute of Scientific and Technical Information of China (English)

    王杰贵; 张鹏程

    2015-01-01

    目前对线性调频(LFM)脉冲压缩雷达转发欺骗干扰主要通过移频调制转发和采样直接转发实现,常规转发干扰样式简单,干扰信号规律性强、复杂度低。该文提出一种基于间歇采样的多载波调制转发新型干扰样式。首先引用码片的概念对间歇采样过程重新建模,在此基础上,通过对当前采样码片附加不同移频量,结合多载波并行调制体制对其进行串并转换,利用不同次转发信号各子载波间的干扰累积,实现对LFM脉冲压缩雷达的数量、幅度、空间分布可控的逼真假目标干扰。仿真表明该干扰样式比移频干扰和直接转发干扰具有更好的干扰效果。%Repeater deception jamming against Linear Frequency Modulated (LFM) pulse-compression radar is realized by frequency-shift repeater and direct repeater jamming so far. Conventional repeater jamming type is simple. Regularity of jamming signal is strong and complexity is low. A new repeater jamming type with multi-carrier modulation based on intermittent sampling is proposed. Firstly, the model of intermittent sampling is rebuilt with the code chip concept. Based on this, lifelike false targets with the quantity, amplitude and space distribution which can be controlled are produced by attaching different frequency-shift component to the present sampling code chip, deserializing signal used multi-carrier parallel modulation system and utilizing the accumulation of different times repeater signal jamming effect among sub-carriers. The simulation results show that the new jamming type has better performance than frequency-shift jamming and direct repeater jamming.

  9. 基于布里渊载波相移的宽带可调谐二倍频微波信号生成*%Widely tunable frequency-doubling microwaves generated using Brillouin-assisted carrier phase shift

    Institute of Scientific and Technical Information of China (English)

    郑狄; 潘炜; 闫连山; 罗斌; 邹喜华; 刘新开; 易安林

    2014-01-01

    本文提出并实验验证了一种基于光纤中受激布里渊散射效应的光子二倍频微波信号生成技术。利用布里渊增益谱内的强色散特性,对光强度调制器产生的双边带调制信号的载波进行π/2相移,可实现载波与±1阶边带拍频仅生成二倍频微波信号。由于光纤中受激布里渊散射的窄带特性以及仅对双边带调制信号的载波进行相移,不影响调制信号两个边带的幅值和相位,因而生成的二倍频微波信号可实现宽带调谐,调谐范围仅受其他光器件的工作带宽限制。此外,信号光和产生受激布里渊散射的抽运光均来自同一光源,因而不受波长漂移的影响,系统具良好的稳定性。%An optically tunable frequency-doubling microwave generation technique based on stimulated Brillouin scattering (SBS) in optical fibers is proposed and experimentally demonstrated. Due to the strong dispersion characteristics in SBS, when a π/2 phase shift is imposed on the optical carrier of an amplitude-modulated signal by SBS, only a frequency-doubling microwave signal from the beating between the optical carrier and the ±1st sidebands is generated. Due to the inherent narrowband character of SBS and the phase shift being only imported on to the optical carrier while the sidebands are kept unchanged, the frequency-doubling with large frequency tunability is realized, the operational bandwidth is just limited by other optical device deployed. In addition, all the required optical signals and pumps can be generated from the same laser source, the influence from the wavelength drifting is eliminated, so the stability of the system is established.

  10. Hydrogen carriers

    Science.gov (United States)

    He, Teng; Pachfule, Pradip; Wu, Hui; Xu, Qiang; Chen, Ping

    2016-12-01

    Hydrogen has the potential to be a major energy vector in a renewable and sustainable future energy mix. The efficient production, storage and delivery of hydrogen are key technical issues that require improvement before its potential can be realized. In this Review, we focus on recent advances in materials development for on-board hydrogen storage. We highlight the strategic design and optimization of hydrides of light-weight elements (for example, boron, nitrogen and carbon) and physisorbents (for example, metal-organic and covalent organic frameworks). Furthermore, hydrogen carriers (for example, NH3, CH3OH-H2O and cycloalkanes) for large-scale distribution and for on-site hydrogen generation are discussed with an emphasis on dehydrogenation catalysts.

  11. 基于遗传算法的OFDM高精度盲频偏估计器%High Accuracy Blind Carrier Frequency Offset Estimator Based on Genetic Algorithm for OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    杨朝阳; 杨霄鹏; 李腾; 姚昆; 倪娟

    2014-01-01

    针对正交频分复用系统频偏估计问题,提出了一种基于遗传算法的高精度盲频偏估计器。该算法首先将带载波间干扰的正交频分复用系统视为正交码分多址接入系统,将载波间干扰系数视为码分多址接入系统的扩频码,利用估计的载波频偏构造扩频码,进而重建接收信号;然后利用重建信号跟实际接收信号最小重建误差原则构造了盲频偏估计的代价函数,并设计了对应于遗传算法的适应度函数;最后利用遗传算法强大的并行搜索和全局寻优能力,通过最小化代价函数求得最佳频偏估值。仿真结果表明,所提算法具有较高的估计精度,低信噪比下性能显著,有效降低了时间复杂度,且不受频偏估计范围和信号调制类型的限制。%For the frequency offset estimation in Orthogonal Frequency Division Multiplexing( OFDM) sys-tems,a high accuracy blind carrier frequency offset estimator is proposed. The OFDM system with inter-carrier interference( ICI) is considered as a multi-carrier CDMA system and the ICI coefficient matrix is considered as the spreading codes in CDMA system. The spreading code is designed with estimated fre-quency offset to reconstruct the received signal. The cost function is constructed based on minimum recon-struction error principle between the received signal and actual received signal,and the fitness function is also designed corresponding to the genetic algorithm ( GA ) . With the strong ability of parallel search and global optimization property of the genetic algorithm,the appropriate frequency offset value is achieved by minimizing the cost function. The simulation results show the proposed algorithm performs higher estimation accuracy than conventional methods,especially in low signal-to-noise ratio( SNR) condition,and it reduces time complexity effectively,without the limitation of frequency offset estimation range and modulation type.

  12. Single-antenna Blind Signal Separation Algorithm for Time-frequency Overlapped Digital Communication Signal with Distinct Carrier Frequency%单天线接收时频混叠的异频数字通信信号盲源分离算法

    Institute of Scientific and Technical Information of China (English)

    庞利会; 王军; 唐斌

    2015-01-01

    本文针对单天线接收时频混叠数字通信信号的盲源分离问题,基于源信号之间载波差异性,构建单天线接收信号虚拟多通道模型,实现了源信号分离与重构。该算法通过对单天线接收混合信号进行短时傅里叶变换,分析各个中心频率的源信号频域特性,提取各个源信号的幅度与相位信息。利用提取信息,实现源信号分离与重构。仿真结果表明,该算法可以有效的实现单天线接收时频混叠数字通信信号的盲源分离。%In this paper,based on the carrier frequency distinct feature among original sources,a blind signal separation method is proposed for the single-antenna time-frequency overlapped digital communication signal.The method changes the single-antenna recording into multi-channel model based the feature that the carrier frequency of original sources are differ-ent from each other.Then,the method analyzes spectral information obtained by the short time Fourier transform to extract amplitude and phase values at each center frequency of overlapped signals.Using those extracted information enables sig-nals from single-antenna data to be separated and reconstructed.The simulation tests demonstrate the feasible feasibility of the proposed approach for single-channel time-frequency overlapped digital communication signal separation.

  13. Carrier frequency of a nonsense mutation in the adenosine deaminase (ADA) gene implies a high incidence of ADA-deficient severe combined immunodeficiency (SCID) in Somalia and a single, common haplotype indicates common ancestry.

    Science.gov (United States)

    Sanchez, Juan J; Monaghan, Gemma; Børsting, Claus; Norbury, Gail; Morling, Niels; Gaspar, H Bobby

    2007-05-01

    Inherited adenosine deaminase (ADA) deficiency is a rare metabolic disorder that causes immunodeficiency, varying from severe combined immunodeficiency (SCID) in the majority of cases to a less severe form in a small minority of patients. Five patients of Somali origin from four unrelated families, with severe ADA-SCID, were registered in the Greater London area. Patients and their parents were investigated for the nonsense mutation Q3X (ADA c7C>T), two missense mutations K80R (ADA c239A>G) and R142Q (ADA c425G>A), and a TAAA repeat located at the 3' end of an Alu element (AluVpA) positioned 1.1 kb upstream of the ADA transcription start site. All patients were homozygous for the haplotype ADA-7T/ADA-239G/ADA-425G/AluVpA7. Among 207 Somali immigrants to Denmark, the frequency of ADA c7C>T and the maximum likelihood estimate of the frequency of the haplotype ADA-7T/ADA-239G/ADA-425G/AluVpA7 were both 0.012 (carrier frequency 2.4%). Based on the analysis of AluVpA alleles, the ADA c7C/T mutation was estimated to be approximately 7,100 years old. Approximately 1 out of 5 - 10000 Somali children will be born with ADA deficiency due to an ADA c7C/T mutation, although within certain clans the frequency may be significantly higher. ADA-SCID may be a frequent immunodeficiency disorder in Somalia, but will be underdiagnosed due to the prevailing socioeconomic and nutritional deprivation.

  14. Cognitive digital receiver for burst mode phase modulated radio over fiber links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Tafur Monroy, Idelfonso

    2010-01-01

    A novel cognitive receiver for modulation format recognition with reconfigurable carrier recovery scheme is proposed and experimentally demonstrated for phase modulated radio-over-fibre links. Demodulation of burst-mode mixed modulation formats (PSK and QAM) is demonstrated after 40km...

  15. Carrier mobility of highly transparent conductive Al-doped ZnO polycrystalline films deposited by radio-frequency, direct-current, and radio-frequency-superimposed direct-current magnetron sputtering: Grain boundary effect and scattering in the grain bulk

    Science.gov (United States)

    Nomoto, Junichi; Makino, Hisao; Yamamoto, Tetsuya

    2015-01-01

    The effects of using radio-frequency (RF)-superimposed direct-current (DC) magnetron sputtering deposition on the structural, electrical, and optical properties of aluminum-doped ZnO (AZO)-based highly transparent conducting oxide films have been examined. AZO films were deposited on heated non-alkaline glass substrates (200 °C) using ZnO:Al2O3 (2 wt. % Al2O3) ceramic oxide targets with the total power varied from 150 to 300 W, and at various RF to DC power ratios, AZO films deposited by a mixed approach with the RF to the total power ratio of 0.14 showed the lowest resistivity of 2.47 × 10-4 Ω cm with the highest carrier concentration of 6.88 × 1020 cm-3 and the highest Hall mobility (μH) of 36.8 cm2/Vs together with the maximum value of an average transmittance in the visible spectral range from 400 to 700 nm. From the analysis of optical data based on the simple Drude model combined with the Tauc-Lorentz model and the results of Hall effect measurements, the optical mobility (μopt) was determined. A comparison of μopt with μH clarified the effects of the mixed approach not only on the reduction of the grain boundary contribution to the carrier transport but also on retaining high carrier mobility of in-grains for the AZO films.

  16. Responsible implementation of expanded carrier screening.

    Science.gov (United States)

    Henneman, Lidewij; Borry, Pascal; Chokoshvili, Davit; Cornel, Martina C; van El, Carla G; Forzano, Francesca; Hall, Alison; Howard, Heidi C; Janssens, Sandra; Kayserili, Hülya; Lakeman, Phillis; Lucassen, Anneke; Metcalfe, Sylvia A; Vidmar, Lovro; de Wert, Guido; Dondorp, Wybo J; Peterlin, Borut

    2016-06-01

    This document of the European Society of Human Genetics contains recommendations regarding responsible implementation of expanded carrier screening. Carrier screening is defined here as the detection of carrier status of recessive diseases in couples or persons who do not have an a priori increased risk of being a carrier based on their or their partners' personal or family history. Expanded carrier screening offers carrier screening for multiple autosomal and X-linked recessive disorders, facilitated by new genetic testing technologies, and allows testing of individuals regardless of ancestry or geographic origin. Carrier screening aims to identify couples who have an increased risk of having an affected child in order to facilitate informed reproductive decision making. In previous decades, carrier screening was typically performed for one or few relatively common recessive disorders associated with significant morbidity, reduced life-expectancy and often because of a considerable higher carrier frequency in a specific population for certain diseases. New genetic testing technologies enable the expansion of screening to multiple conditions, genes or sequence variants. Expanded carrier screening panels that have been introduced to date have been advertised and offered to health care professionals and the public on a commercial basis. This document discusses the challenges that expanded carrier screening might pose in the context of the lessons learnt from decades of population-based carrier screening and in the context of existing screening criteria. It aims to contribute to the public and professional discussion and to arrive at better clinical and laboratory practice guidelines.

  17. Responsible implementation of expanded carrier screening

    Science.gov (United States)

    Henneman, Lidewij; Borry, Pascal; Chokoshvili, Davit; Cornel, Martina C; van El, Carla G; Forzano, Francesca; Hall, Alison; Howard, Heidi C; Janssens, Sandra; Kayserili, Hülya; Lakeman, Phillis; Lucassen, Anneke; Metcalfe, Sylvia A; Vidmar, Lovro; de Wert, Guido; Dondorp, Wybo J; Peterlin, Borut

    2016-01-01

    This document of the European Society of Human Genetics contains recommendations regarding responsible implementation of expanded carrier screening. Carrier screening is defined here as the detection of carrier status of recessive diseases in couples or persons who do not have an a priori increased risk of being a carrier based on their or their partners' personal or family history. Expanded carrier screening offers carrier screening for multiple autosomal and X-linked recessive disorders, facilitated by new genetic testing technologies, and allows testing of individuals regardless of ancestry or geographic origin. Carrier screening aims to identify couples who have an increased risk of having an affected child in order to facilitate informed reproductive decision making. In previous decades, carrier screening was typically performed for one or few relatively common recessive disorders associated with significant morbidity, reduced life-expectancy and often because of a considerable higher carrier frequency in a specific population for certain diseases. New genetic testing technologies enable the expansion of screening to multiple conditions, genes or sequence variants. Expanded carrier screening panels that have been introduced to date have been advertised and offered to health care professionals and the public on a commercial basis. This document discusses the challenges that expanded carrier screening might pose in the context of the lessons learnt from decades of population-based carrier screening and in the context of existing screening criteria. It aims to contribute to the public and professional discussion and to arrive at better clinical and laboratory practice guidelines. PMID:26980105

  18. New Concept of PLC Modems: Multi-Carrier System for Frequency Selective Slow-Fading Channels Based on Layered SCCC Turbocodes

    Directory of Open Access Journals (Sweden)

    J. Zavrtalek

    2015-09-01

    Full Text Available The article introduces a novel concept of a PLC modem as a complement to the existing G3 and PRIME standards for communications using medium- or high-voltage overhead or cable lines. The proposed concept is based on the fact that the levels of impulse noise and frequency selectivity are lower on high-voltage lines than on low-voltage ones. Also, the demands for “cost-effective” circuitry design are not so crucial as in the case of modems for low-voltage level. In contract to these positive conditions, however, there is the need to overcome much longer distances and to take into account low SNR on the receiving side. With respect to the listed reasons, our concept makes use of MCM, instead of OFDM. The assumption of low SNR is compensated through the use of an efficient channel coding based on a serially concatenated turbo code. In addition, MCM offers lower latency and PAPR compared to OFDM. Therefore, when using MCM, it is possible to excite the line with higher power. The proposed concept has been verified during experimental transmission of testing data over a real, 5 km long, 22kV overhead line.

  19. Orthogonal Frequency Division Multiplexing System with Frequency Offset Estimation

    Directory of Open Access Journals (Sweden)

    Meghashree D.Nimje

    2013-03-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM system, use a large number of parallel narrowband subcarriers instead of a single wide-band carrier to transport information. Orthogonal frequency division multiplexing is the modulation technique use in digital communication systems . Carrier frequency offset occurs due to Doppler effect or noise. Carrier frequency offsets (CFOs is the Offset between the transmitter and the receiver oscillators .CFO damages the orthogonality of the carries ,resulting in degradation of the systems performance. Carrier frequency offset estimation method is discussed in this paper. In this paper one complex training sequence use, which can effectively estimate carrier frequency offset in the time domain and frequency domain. Here fine and coarse frequency is estimated to improve the improve the system performance. This paper shows the estimation range for frequency offset can be improve to large extent..

  20. Loop Design of Digital Intermediate Frequency Receiving Machine Based on Carrier Track Technique of Frequency Lock Associated with Phase Lock%基于载波锁频锁相联合跟踪的数字中频接收机环路设计

    Institute of Scientific and Technical Information of China (English)

    王光鼎; 游福初; 房建成

    2012-01-01

    介绍了接收卫星信号的数字中频接收机载波同步跟踪关键技术,针对高机动环境下载波同步需要解决的捕获带宽、捕获速度与跟踪精度的矛盾,综合利用了传统数字锁频环路(DFLL)和数字锁相环路(DPLL)的优点,设计了一种适合高机动环境下数字中频接收机的锁频联合锁相环工作的环路方案。并利用计算机仿真分析结果,证明了该方案的可行性和优越性,为ADC+FPGA+DSP框架下卫星信号数字中频接收机软硬件实现提供了设计依据。%The carrier synchronization track technique of digital intermediate frequency receiving machine is introduced, which is important for receiving the signal of satellites. In the seriously dynamic situation, the inconsistency among the bandwidth, velocity and precision of capture for carrier synchronization should be resolved. Integrating the traditional FDLL and DPLL, a new loop project is designed, which frequency lock associated with phase lock, and it' s suitable for digital intermediate frequency receiving machine in seriously dynamic situation. The analysis and simulation by computer is carried out, and the feasibility and advantage are proved. Then the hardware framework with ADC + FPGA + DSP for digital intermediate frequency receiving machine of satellite signal is well-founded.

  1. 改进频率鉴别的载波跟踪环路及性能分析%Carrier tracking loop based on improved frequency detector and its performance analysis

    Institute of Scientific and Technical Information of China (English)

    王俊; 孙昕

    2012-01-01

    To meet the high dynamic environment, global navigation satellite system receivers often combine frequency-locked loop with phase-locked loop to track carrier. An improvement on cross-product automatic frequency control loop, which is commonly used, is proposed. The new loop adopts the switch between two identification methods. As a result, it can overcome the data ambiguity and expand the frequency discrimination range 4 times while maintaining the same tracking accuracy. The main factors affecting the tracking accuracy include noise tracking error and dynamic stress error. It is found that there is a greater gap between the traditional theory of thermal noise error and actual results. Using loop linear approximation and considering the relevance of noises in identification results, the new thermal noise tracking error equation is derived. The new value is less than one-fifth of traditional theoretical analysis. Finally, the analysis of frequency discrimination range and thermal noise tracking error is proved by simulation results.%为了适应高动态环境,导航接收机常采取锁频环和锁相环联合工作实现载波跟踪.对其中较常用的的叉积自动频率跟踪环提出改进,利用两种方法切换实现频率鉴别.改进后算法克服了数据位模糊,并且使鉴频范围扩大了4倍,同时保持跟踪精度不变.影响跟踪精度的因素主要包括热噪声误差和动态应力误差,经研究发现其中热噪声误差的传统理论分析结果与实际有较大差距.利用环路线性化近似处理,并且考虑鉴别噪声间的相关性,经重新推导得到锁频环路的热噪声跟踪误差低于传统理论分析结果的1/5.通过仿真对锁频环鉴频范围和热噪声跟踪误差分析的正确性进行了验证.

  2. 基于光载波抑制调制的星间微波光子下变频研究%Research on inter-satellite microwave photonic frequency down conversion based on optical carrier suppression modulation

    Institute of Scientific and Technical Information of China (English)

    李轩; 赵尚弘; 张薇; 朱子行; 韩磊; 赵静

    2013-01-01

    To solve the problem of optical handling of microwave signal in satellite communication,the inter-satellite microwave photonic frequency down conversion system is modeled,two parallel dual-electrode Mach-Zehnder modulators based on optical carrier suppression modulation are utilized to modulate the uplink microwave signal received by satellite and the local oscillator signal produced in satellite,respectively,and the microwave signal is optically amplified,transmitted and frequency-down converted in the inter-satellite optical link.The output signal and noise of system are analyzed with Bessel expansion,the local oscillator signal power is optimized,and the effects of modulator bias phase drift,phase shifter error and emission optical power on the system performance are simulated.The results show that the deterioration of output carrier to noise ratio (CNR) is under 0.05 dB while the modulator bias phase drift is less than 5 ℃,the output CNR deterioration is under 0.02 dB while the phase shifter error is less than 5 ℃,and the frequency down conversion system has high stability.When the emission optical power is 10.48 dB,the system output CNR is 31.33 dB,which can meet the practical requirement.The inter-satellite microwave photonic frequency down conversion system can be applied to the optical handling of microwave signal in the future satellite optical communications.%针对卫星通信中微波信号光学处理问题,建立了星间微波光子下变频系统模型,采用两个双电极马赫-曾德尔调制器(DE-MZM)并联形式,以光载波抑制(DCS)方式实现了星间微波信号的光域放大、传输和下变频.利用贝塞尔函数展开分析了下变频系统中信号和各噪声分量,对射频本振信号功率进行了优化,仿真研究了调制器直流偏置漂移、移相器相移误差和发射光功率对系统性能的影响.结果表明,调制器直流偏置相位漂移小于5℃时输出载噪比(CNR)恶化小于0.05 dB

  3. Maximum Likelihood TOA Estimation Algorithm Based on Multi-carrier Time-frequency Iteration%基于多载波时频迭代的最大似然TOA估计算法

    Institute of Scientific and Technical Information of China (English)

    程刘胜

    2015-01-01

    在合理布局井下无线网络基站的基础上,提出了一种基于多载波时频迭代的最大似然TOA(Time of Arrival)估计算法,通过将小数延时不断迭代来缩小估计误差,确定合适搜索步长,实现对信号的精确TOA估计。仿真结果表明:时频迭代的最大似然TOA估计算法具有更快的收敛速度;在信噪比较小时,采用时频迭代的最大似然TOA估计算法比经典TOA估计算法有效地提高了估计精度。%The influence of underground multipath, non-line of sight and the network time synchronization accuracy cause that delayed arrival time estimation deviation is bigger in the mining UWB high accuracy position system. This paper proposes a maximum likelihood TOA estimation algorithm based on multi-carrier time-frequency iteration by rationally distributing the underground wireless base stations to conform a suitable searching step length and find the exact TOA approximation estimation to the signal via fractional delay iterated to narrow the estimation error. The result shows that the time frequency iteration TOA estimation has a faster rate of convergence than the non-iteration algorithm.

  4. Integrated 10 Gb/s multilevel multiband passive optical network and 500 Mb/s indoor visible light communication system based on Nyquist single carrier frequency domain equalization modulation.

    Science.gov (United States)

    Wang, Yuanquan; Shi, Jianyang; Yang, Chao; Wang, Yiguang; Chi, Nan

    2014-05-01

    We propose and experimentally demonstrate a novel integrated passive optical network (PON) and indoor visible light communication (VLC) system based on Nyquist single carrier frequency domain equalization (N-SC-FDE) modulation with direct detection. In this system, a directly modulated laser and a commercially available red light emitting diode are served as the transmitters of the PON and VLC, respectively. To enable high spectral efficiency, high-speed transmission, and flexible multiple access with simplified optical network unit-side digital signal processing, multilevel, multiband quadrature amplitude modulations 128/64/16 are implemented here. VLC N-SC-FDE signals are successfully delivered a further 30 cm indoor distance after transmitting over a span of 40 km single mode fiber (SMF) together with 3 sub-band PON signals. As a proof of concept, a 10 Gb/s PON and 500 Mb/s VLC integrated system for three wired users and one wireless user is successfully achieved, which shows the promising potential and feasibility of this proposal to extend multiple services from metropolitan to suburban areas.

  5. Improved carrier frequency offset estimation algorithm for wireless sensor networks%无线传感网载波频率偏移估计方法的改进

    Institute of Scientific and Technical Information of China (English)

    王翔; 罗炬锋; 付耀先; 王营冠

    2011-01-01

    In wireless sensors networks, for low-power and low-cost requirements, the device should rapidly complete accurate carrier frequency offset estimation in low SNR environment to ensure reliable data transmission. It is necessary to develop the estimation algorithm of low SNR and large estimation range. Fitz algorithm is a classical method of frequency offset estimation, with advantage of high accuracy and low estimation SNR threshold. But it is inverse relationship between the estimation range and the estimation accuracy. This paper introduced a new iterative method to improve Fitz' s algorithm which unwrapped the angular of auto-correlation function to calculate the carrier frequency offset. The new algorithm expanded the estimate range while kept the advantages of high accuracy and low estimation thresh of Fitz algorithm. The simulation results show that the new algorithm' s estimation range close to ± 50% of the symbol period, the estimation accuracy close to lower limit of to the CRLB, and the estimation SNR threshold 2 dB lower than other algorithms. This algorithm can meet the accuracy and range re quirement of wireless sensor network at the same time.%无线传感网的低功耗、低成本等特性,要求设备能在低信噪比环境下快速完成突发通信的载波频偏估计,保证数据传输的正确性,因而需要对低信噪比和大频偏范围的频偏估计算法进行研究.Fitz算法是较为经典的载波频率偏移估计方法,具有算法精确度高和估计信噪比门限低等优点,但此算法的频偏估计范围与精度之间呈反比关系,频偏估计范围越大,估计精度越低.针对Fitz算法进行改进,利用迭代的方法展开信号自相关相位,代入Fitz算法估计载波频偏,在保持Fitz算法精确度高和估计信噪比门限低优点的同时,将其估计范围扩大了M倍,M为最大自相关阶数.实验结果表明,改进算法的频偏估计范围接近±50%的符号周期,估计精确度接近

  6. Simulation of dual transponder carrier ranging measurements

    Institute of Scientific and Technical Information of China (English)

    Xiang-yu ZHAO; Xiao-jun JIN; Zhong-he JIN

    2009-01-01

    The most dominant error source for microwave ranging is the frequency instability of the oscillator that generates the carrier phase signal. The oscillator noise is very difficult to filter due to its extremely low frequency. A dual transponder carrier ranging method can effectively minimize the oscillator noise by combing the reference phase and the to-and-fro measurement phase from the same single oscillator. This method does not require an accurate time tagging system, since it extracts phases on the same satellite. This paper analyzes the dual transponder carrier ranging system by simulation of the phase measurements with comprehensive error models. Both frequency domain and time domain noise transfer characteristics were simulated to compare them with dual one-way ranging. The simulation results in the two domains conformed to each other and demonstrated that a high level of accuracy can also be achieved by use of the dual transponder carrier ranging system, with relatively simple instruments.

  7. Triple-frequency carrier phase ambiguity resolution for BeiDou navigation satellite system%北斗系统三频载波相位整周模糊度快速解算

    Institute of Scientific and Technical Information of China (English)

    王兴; 刘文祥; 陈华明; 孙广富

    2015-01-01

    北斗导航定位系统播发三个频率观测值,有助于载波相位整周模糊度的快速、准确固定。传统的几何无关模型三频载波相位模糊度固定算法通常采用遍历整数搜索的方法确定载波相位-伪距组合系数,组合后的噪声因子较大,模糊度固定成功率不高。在分析了北斗系统伪距测量误差特性的基础上,给出了加权组合噪声因子的定义及其约束下的最优组合系数的求解方法。采用Hatch滤波提高电离层延时误差实时估计精度,成功固定三组线性无关组合系数对应整周模糊度,进而确定基础整周模糊度。利用北斗系统短基线、长基线实测数据对算法性能进行了验证,实验表明:提出的算法可优化超宽巷、宽巷组合噪声因子20%以上,模糊度固定成功率提高10%~18%左右,30s历元平滑后的基础模糊度固定成功率可达90%以上。%BeiDou navigation satellite system transmits triple-frequency signals which are benefit for the fast and accurate fixation of carrier phase integer ambiguity.Traditional TCAR (Three Carrier Ambiguity Resolution ) method based on geometry-free model finds the suitable combination coefficients of carrier phase and pseudo-range observations by using traversal integer search method,which makes the higher noise level and the lower success reliability.In the analysis of the error characteristics of the pseudo-range observations,the weighted combined noise level was defined and a new procedure within its constrains to select the optimal combination coefficients was introduced.With using Hatch filter to improve the real-time estimation accuracy of ionospheric delay,the integer ambiguity of three linearly independent combination coefficients was fixed successfully,thus the basic integer ambiguities were determined.Finally,the performances of the improved TCAR are showed both in short-baseline and long-baseline condition:compared with

  8. A Customized Finger Brachytherapy Carrier

    OpenAIRE

    Wadhwa, Supneet Singh; Duggal, Nidhi

    2013-01-01

    In recent years, radiation therapy has been used with increasing frequency in the management of neoplasms of the head and neck region. Brachytherapy is a method of radiation treatment in which sealed radioactive sources are used to deliver the dose a short distance by interstitial (direct insertion into tissue), intracavitary (placement within a cavity) or surface application (molds). Mold brachytherapy is radiation delivered via a custom-fabricated carriers, designed to provide a more consta...

  9. Carrier-dependent temporal processing in an auditory interneuron.

    Science.gov (United States)

    Sabourin, Patrick; Gottlieb, Heather; Pollack, Gerald S

    2008-05-01

    Signal processing in the auditory interneuron Omega Neuron 1 (ON1) of the cricket Teleogryllus oceanicus was compared at high- and low-carrier frequencies in three different experimental paradigms. First, integration time, which corresponds to the time it takes for a neuron to reach threshold when stimulated at the minimum effective intensity, was found to be significantly shorter at high-carrier frequency than at low-carrier frequency. Second, phase locking to sinusoidally amplitude modulated signals was more efficient at high frequency, especially at high modulation rates and low modulation depths. Finally, we examined the efficiency with which ON1 detects gaps in a constant tone. As reflected by the decrease in firing rate in the vicinity of the gap, ON1 is better at detecting gaps at low-carrier frequency. Following a gap, firing rate increases beyond the pre-gap level. This "rebound" phenomenon is similar for low- and high-carrier frequencies.

  10. Selection of Carrier Waveforms for PWM Inverter

    Institute of Scientific and Technical Information of China (English)

    陈国呈; 屈克庆; 许春雨; 孙承波

    2003-01-01

    In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonancetrigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.

  11. Hiding secret data into a carrier image

    OpenAIRE

    Ovidiu COSMA

    2012-01-01

    The object of steganography is embedding hidden information in an appropriate multimedia carrier, e.g., image, audio, or video. There are several known methods of solving this problem, which operate either in the space domain or in the frequency domain, and are distinguished by the following characteristics: payload, robustness and strength. The payload is the amount of secret data that can be embedded in the carrier without inducing suspicious artefacts, robustness indicates the degree in wh...

  12. A Novel Bind Carrier Frequency Offset Estimation Method in SCM-OFDM Systems%SCM-OFDM系统中一种新型的盲频偏估计方法

    Institute of Scientific and Technical Information of China (English)

    彭涛; 肖悦; 叶敏; 李少谦

    2013-01-01

    A Carrier Frequency Offset (CFO) estimation method is proposed based on signal detection in Superposition Coded Modulation (SCM)-OFDM systems. This method reconstructs first the received signal by decision symbols from the SCM iterative detector, and then estimates the CFO by employing the Minimum Mean Squared Error (MMSE) criterion. It is an efficient blind CFO estimation method without the aid of extra training sequences or pilot symbols. Furthermore, an improved method is proposed to estimate CFO in this paper. In the improved method, a joint CFO estimation and signal detection receiver is realized by an iterative process. Thus data detection and CFO estimation need to be implemented in each iteration process. And the receiver can compensate the CFO by the last estimated value during signal detection. Simulation results show that the proposed CFO estimation methods can significantly and accurately estimate the CFO for SCM-OFDM systems.%  该文提出了一种用于重叠码调制-正交频分复用(SCM-OFDM)系统中基于信号检测的频偏估计方法。这种估计方法首先利用SCM迭代检测器输出的判决符号重构接收信号,再利用最小均方误差准则对频偏进行估计。该方法不需要额外的训练序列或导频符号,是一种高效的盲频偏估计方法。此外,该文还提出了一种改进的频偏估计方法。在改进的方法中,接收机将频偏估计与信号检测进行联合迭代;这样在每一次迭代过程中,信号检测和频偏估计都需要执行一次,并且接收机在信号检测时可以利用上一次得到的频偏估计值进行频偏补偿。仿真结果表明,该文提出的基于信号检测的频偏估计方法能够高效并准确地估计出SCM-OFDM系统的频偏。

  13. An Efficient Inter Carrier Interference Cancellation Schemes for OFDM Systems

    Directory of Open Access Journals (Sweden)

    B. Sathish Kumar

    2009-12-01

    Full Text Available Orthogonal Frequency Division Multiplexing (OFDM has recently been used widely in wireless communication systems. OFDM is very effective in combating inter-symbol interference and can achieve high data rate in frequency selective channel. For OFDM communication systems, the frequency offsets in mobile radio channels distort the orthogonality between subcarriers resulting in Inter Carrier Interference (ICI. ICI causes power leakage among subcarriers thus degrading the system performance. A well-known problem of OFDM is its sensitivity to frequency offset between the transmitted and received carrier frequencies. There are two deleterious effects caused by frequency offset one is the reduction of signal amplitude in the output of the filters matched to each of the carriers and the second is introduction of ICI from the other carriers. This research work investigates three effective methods for combating the effects of ICI: ICI Self Cancellation (SC, Maximum Likelihood (ML estimation, and Extended Kalman Filter (EKF method. These three methods are compared in terms of bit error rate performance and bandwidth efficiency. Through simulations, it is shown that the three techniques are effective in mitigating the modulation schemes, the ML and EKF methods perform better than the SC method.Keywords- Orthogonal frequency Division Multiplexing (OFDM; Inter Carrier Interference(ICI; Carrier to Interference Power Ratio (CIR;Self Cancellation(SC;Carrier Frequency Offset (CFO; Maximum Likelihood(ML; Extended Kalman Filtering(EKF.

  14. Carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool

    Science.gov (United States)

    Cai, Yu; Sha, Shuang

    2016-09-01

    This paper proposes a new carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool used in a cylindrical borehole environment during oil-based mud drilling processes. The new tool is an orthogonal frequency division multiplexing access-based contactless multi-measurand detection tool. The tool can measure formation resistivity in different azimuthal angles and elevational depths. It can measure many more measurands simultaneously in a specified bandwidth than the legacy frequency division multiplexing multi-measurand tool without a channel-select filter while avoiding inter-carrier interference. The paper also shows that formation resistivity is not sensitive to frequency in certain frequency bands. The average resistivity collected from N subcarriers can increase the measurement of the signal-to-noise ratio (SNR) by N times given no amplitude clipping in the current-injection electrode. If the clipping limit is taken into account, with the phase rotation of each single carrier, the amplitude peak-to-average ratio can be reduced by 3 times, and the SNR can achieve a 9/N times gain over the single-carrier system. The carrier-interleaving technique is also introduced to counter the carrier frequency offset (CFO) effect, where the CFO will cause inter-pad interference. A qualitative analysis and simulations demonstrate that block-interleaving performs better than tone-interleaving when coping with a large CFO. The theoretical analysis also suggests that increasing the subcarrier number can increase the measurement speed or enhance elevational resolution without sacrificing receiver performance. The complex orthogonal multi-pad multi-carrier resistivity logging tool, in which all subcarriers are complex signals, can provide a larger available subcarrier pool than other types of transceivers.

  15. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    2015-01-01

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  16. The carrier-generating analysis of MEMS gyroscope interface circuit

    Directory of Open Access Journals (Sweden)

    GuangMin Yuan

    2014-03-01

    Full Text Available In this paper, the main factors which influence the noise ratio of gyroscope output signal were analysed, according to the MEMS gyro interface circuit technology. A working principle of a carrier in the gyroscope circuit was discussed, the process formula of the carrier amplitude and frequency in the interface circuit of modulation and demodulation was deduced, and the error components lead-in from carrier to gyroscope circuit was distinguished. Several commonly used carrier-generating circuit schemes were analysed and compared, and a carrier-generating program in the interface circuits of the micro-gyroscope was designed, which was applied in a MEMS gyro developed by our laboratory. The measurement results show that the amplitude stability and frequency stability is 1.3 ppm and 12 ppm, respectively, meeting the performance requirements of carrier generating in the MEMS gyro circuit.

  17. The carrier-generating analysis of MEMS gyroscope interface circuit

    Science.gov (United States)

    Yuan, GuangMin; Yuan, Weizheng; Zhu, Xiaobo; Chang, HongLong

    2014-03-01

    In this paper, the main factors which influence the noise ratio of gyroscope output signal were analysed, according to the MEMS gyro interface circuit technology. A working principle of a carrier in the gyroscope circuit was discussed, the process formula of the carrier amplitude and frequency in the interface circuit of modulation and demodulation was deduced, and the error components lead-in from carrier to gyroscope circuit was distinguished. Several commonly used carrier-generating circuit schemes were analysed and compared, and a carrier-generating program in the interface circuits of the micro-gyroscope was designed, which was applied in a MEMS gyro developed by our laboratory. The measurement results show that the amplitude stability and frequency stability is 1.3 ppm and 12 ppm, respectively, meeting the performance requirements of carrier generating in the MEMS gyro circuit.

  18. Terahertz carrier dynamics and dielectric properties of GaN epilayers with different carrier concentrations

    Science.gov (United States)

    Guo, H. C.; Zhang, X. H.; Liu, W.; Yong, A. M.; Tang, S. H.

    2009-09-01

    Using terahertz time-domain spectroscopy, we measured the complex conductivity and dielectric function of n-type GaN with various carrier concentrations on sapphire substrate. The measured complex conductivity, which is due to the free carriers, is well fitted by simple Drude model. The contribution from the lattice vibration to the complex dielectric function increases with the decrease in free carrier concentration. A better fitting of the frequency-dependent complex dielectric response was obtained by considering both of the Drude and the classical damped oscillator model.

  19. Composite cam carrier

    Energy Technology Data Exchange (ETDEWEB)

    Wicks, Christopher Donald; Madin, Mark Michael

    2017-03-14

    A cam carrier assembly includes a cylinder head having valves and a camshaft having lobes. A cam carrier has a first side coupled with the cylinder head engaging around the valves and a second side with bearing surfaces supporting the camshaft. A series of apertures extend between the first and second sides for the lobes to interface with the valves. The cam carrier is made of carbon fiber composite insulating the camshaft from the cylinder head and providing substantial weight reduction to an upper section of an associated engine.

  20. Joint Iterative Carrier Synchronization and Signal Detection Employing Expectation Maximization

    DEFF Research Database (Denmark)

    Zibar, Darko; de Carvalho, Luis Henrique Hecker; Estaran Tolosa, Jose Manuel

    2014-01-01

    In this paper, joint estimation of carrier frequency, phase, signal means and noise variance, in a maximum likelihood sense, is performed iteratively by employing expectation maximization. The parameter estimation is soft decision driven and allows joint carrier synchronization and data detection...

  1. Cardiac involvement in carriers of Duchenne and Becker muscular dystrophy

    NARCIS (Netherlands)

    Hoogerwaard, EM; van der Wouw, PA; Wilde, AAM; Bakker, E; Ippel, PF; Oosterwijk, JC; Majoor-Krakauer, DF; van Essen, AJ; Leschot, NJ; de Visser, M

    1999-01-01

    A cross-sectional study in a cohort of DNA proven carriers of Duchenne (DMD) and Becker (BMD) muscular dystrophy was undertaken with the following objectives: (1) to estimate the frequency of electrocardiographic (ECG) and echocardiographic abnormalities; (2) to establish the proportion of carriers

  2. Spread Spectrum Modulation by Using Asymmetric-Carrier Random PWM

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Lungeanu, Florin; Sera, Dezso;

    2012-01-01

    This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on simulations and experimental measurements, it is shown that the spread effect of the discrete components from the motor current spectra and acoustic spectra i...

  3. 多普勒频率变化率快速最大似然估计辅助的高动态载波跟踪环路%Carrier Tracking Loop in High Dynamic Environment Aided by Fast Maximum Likelihood Estimation of Doppler Frequency Rate-of-change

    Institute of Scientific and Technical Information of China (English)

    郇浩; 陶选如; 陶然; 程小康; 董朝; 李鹏飞

    2014-01-01

    To reach a compromise between efficient dynamic performance and high tracking accuracy of carrier tracking loop in high-dynamic circumstance which results in large Doppler frequency and Doppler frequency rate-of-change, a fast maximum likelihood estimation method of Doppler frequency rate-of-change is proposed in this paper, and the estimation value is utilized to aid the carrier tracking loop. First, it is pointed out that the maximum likelihood estimation method of Doppler frequency and Doppler frequency rate-of-change is equivalent to the Fractional Fourier Fransform (FrFT). Second, the estimation method of Doppler frequency rate-of-change, which combines the instant self-correlation and the segmental Discrete Fourier Transform (DFT) is proposed to solve the large two-dimensional search calculation amount of the Doppler frequency and Doppler frequency rate-of-change, and the received coarse estimation value is applied to narrow down the search range. Finally, the estimation value is used in the carrier tracking loop to reduce the dynamic stress and improve the tracking accuracy. Theoretical analysis and computer simulation show that the search calculation amount falls to 5.25 percent of the original amount with Signal to Noise Ratio (SNR)-30 dB, and the Root Mean Sguare Error(RMSE) of frequency tracked is only 8.46 Hz/s, compared with the traditional carrier tracking method the tracking sensitivity can be improved more than 3 dB.%高动态环境下接收信号含有较大的多普勒频率及其变化率,传统载波跟踪方法难以在高动态应力和跟踪精度两方面取得较好折中,针对这一问题该文提出一种多普勒频率变化率快速最大似然估计方法,并利用估计值辅助载波跟踪环路。首先指出了多普勒频率及其变化率的最大似然估计可等效采用分数阶傅里叶变换(FrFT)来实现;其次,针对频率及其变化率2维搜索运算量大的问题,提出一种瞬时自相关与分段离

  4. Dispersion and polarization dependence of mobile carrier optical nonlinearities

    Science.gov (United States)

    Rustagi, K. C.

    1984-06-01

    Based on the author's earlier work, it is shown that the proper inclusion of carrier scattering should strongly modify the frequency and polarization dependence of optical nonlinearities due to mobile carriers in semiconductors. When the momentum relaxation is much faster than the energy relaxation, the intensity dependent refractive index is enhanced, the induced birefringence becomes a sharp function of the difference frequency ωa-ωb, and a collision induced stimulated Raman effect becomes important.

  5. Photoinduced Transformation between Charge Carrier and Spin Carrier in Polymers

    Institute of Scientific and Technical Information of China (English)

    MEI Yuan; ZHAO Chang; SUN Xin

    2006-01-01

    By dynamical simulations, we show a transforming process between neutral soliton (spin carrier) and charged soliton (charge carrier) in polymers via photo-excitation, taking a polaron as the transitional bridge. It is photoinduced transformation between spin carrier and charge carrier. In this way, we demonstrate an access for polymers to be applied to spintronics.

  6. 47 CFR 25.202 - Frequencies, frequency tolerance and emission limitations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Frequencies, frequency tolerance and emission... CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25.202 Frequencies, frequency tolerance and emission limitations. (a)(1) Frequency band. The following frequencies are available for use...

  7. Transmission line model for strained quantum well lasers including carrier transport and carrier heating effects.

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H

    2016-03-01

    This paper reports a new model for strained quantum well lasers, which are based on the quantum well transmission line modeling method where effects of both carrier transport and carrier heating have been included. We have applied this new model and studied the effect of carrier transport on the output waveform of a strained quantum well laser both in time and frequency domains. It has been found that the carrier transport increases the turn-on, turn-off delay times and damping of the quantum well laser transient response. Also, analysis in the frequency domain indicates that the carrier transport causes the output spectrum of the quantum well laser in steady state to exhibit a redshift which has a narrower bandwidth and lower magnitude. The simulation results of turning-on transients obtained by the proposed model are compared with those obtained by the rate equation laser model. The new model has also been used to study the effects of pump current spikes on the laser output waveforms properties, and it was found that the presence of current spikes causes (i) wavelength blueshift, (ii) larger bandwidth, and (iii) reduces the magnitude and decreases the side-lobe suppression ratio of the laser output spectrum. Analysis in both frequency and time domains confirms that the new proposed model can accurately predict the temporal and spectral behaviors of strained quantum well lasers.

  8. PAPR Reduction in OFDM Systems with Large Number of Sub-Carriers by Carrier Interferometry Approaches

    Institute of Scientific and Technical Information of China (English)

    HE Jian-hui; QUAN Zi-yi; MEN Ai-dong

    2004-01-01

    High Peak-to-Average Power Ratio (PAPR) is one of the major drawbacks of Orthogonal Frequency Division Multiplexing ( OFDM) systems. This paper presents the structures of the particular bit sequences leading to the maximum PAPR (PAPRmax) in Carrier-Interferometry OFDM (CI/OFDM) and Pseudo Orthogonal Carrier-Interferometry OFDM (PO-CI/OFDM) systems for Binary Phase Shift Keying (BPSK) modulation. Furthermore, the simulation and analysis of PAPRmax and PAPR cumulative distribution in CI/OFDM and PO-CI/OFDM systems with 2048 sub-carriers are presented in this paper. The results show that the PAPR of OFDM system with large number of sub-carriers reduced evidently via CI approaches.

  9. The value of energy carriers

    NARCIS (Netherlands)

    Gool, W. van

    1987-01-01

    The value of energy carriers can be described thermodynamically by the amount of heat (enthalpy method) or work (exergy or availability method) that can be obtained from the carriers. Prices for energy carriers are used in economics to express their values. The prices for energy carriers are often r

  10. 载噪比加权的GPS单频单历元定姿算法%Carrier to Noise Ratio Weighted Algorithm in GPS Single Epoch Single Frequency Attitude Determination

    Institute of Scientific and Technical Information of China (English)

    金天; 原青; 郑光辉; 张立杨; 张军

    2014-01-01

    In GPS attitude determination system to deal with the problem that the traditional elevation weighted algorithm can’t reflect the situation of occlusion effectively,the accuracy of carrier phase by the satellite carrier to noise ratio of receiver is analyzed in this paper,and a new algorithm based on weighted matrixW is proposed.In the new algorithm,the leastGsquares (ILS)are used to estimate ambiguity and baseline vector.The proposed algorithm can improve the success rate under situation when satellite signal is weak and precision of carrier phase is low.By comparative experiments,it is verified the rationality and effectiveness of the proposed algorithm.Simulation results show that the proposed CN0 weighted algorithm can increase the success rate of single epoch attitude determination by 5 percent compared to the traditional algorithm,1~2 percent compared to the elevation weighted algorithm.%针对GPS定姿系统中,传统的利用高度角的加权不能有效反映遮挡情况的问题,从接收机的卫星载噪比出发,对载波相位精度进行分析,提出新的权重矩阵W,对观测模型进行加权。加权后模型根据最小二乘得到整周模糊度和基线矢量的浮点解。加权方法能够降低弱信号卫星的载波相位观测值对姿态测量成功率的影响。通过对比试验验证了加权算法的合理性和有效性。部分试验结果表明,相比于未加权算法,载噪比加权算法可以使单历元定姿成功率提高5个百分点;相比于高度角加权算法,载噪比加权可以使成功率提高1~2个百分点。

  11. Hiding secret data into a carrier image

    Directory of Open Access Journals (Sweden)

    Ovidiu COSMA

    2012-06-01

    Full Text Available The object of steganography is embedding hidden information in an appropriate multimedia carrier, e.g., image, audio, or video. There are several known methods of solving this problem, which operate either in the space domain or in the frequency domain, and are distinguished by the following characteristics: payload, robustness and strength. The payload is the amount of secret data that can be embedded in the carrier without inducing suspicious artefacts, robustness indicates the degree in which the secret data is affected by the normal processing of the carrier e.g., compression, and the strength indicate how easy the presence of hidden data can be detected by steganalysis techniques. This paper presents a new method of hiding secret data into a digital image compressed by a technique based on the Discrete Wavelet Transform (DWT [2] and the Set Partitioning In Hierarchical Trees (SPIHT subband coding algorithm [6]. The proposed method admits huge payloads and has considerable strength.

  12. Carrier transport uphill. I. General

    DEFF Research Database (Denmark)

    Rosenberg, T; Wilbrandt, W

    1963-01-01

    A quantitative treatment of a carrier pump operating with two carrier forms C and Z is presented. Asymmetric metabolic reactions are assumed to transform Z into C on one and C into Z on the other side of the membrane, establishing a carrier cycle. The kinetical consequences of this mechanism...... concords with equilibrating carrier systems in all characteristic kinetical features is taken to indicate that the carrier mechanism contributes more to the characteristic transport features than the connection with metabolism....

  13. Carrier dynamics and gain spectra at room-temperature in epitaxial ZNO thin films

    DEFF Research Database (Denmark)

    Yu, Ping; Hvam, Jørn Märcher; Wong, K. S.

    1999-01-01

    Carrier dynamics of epitaxial ZnO thin film was investigated using a frequency up-conversion tehcnique. At lower carrier densities, the decay time of free exciton recombination was measured to be 24 ps. Rapid decay times of a few picoseconds were observed at higher carrier densities, which show a...

  14. Extracting hot carriers from photoexcited semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang

    2014-12-10

    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.

  15. Intestinal solute carriers

    DEFF Research Database (Denmark)

    Steffansen, Bente; Nielsen, Carsten Uhd; Brodin, Birger

    2004-01-01

    A large amount of absorptive intestinal membrane transporters play an important part in absorption and distribution of several nutrients, drugs and prodrugs. The present paper gives a general overview on intestinal solute carriers as well as on trends and strategies for targeting drugs and/or pro...

  16. Performance Analysis of MC-CDMA in the Presence of Carriers Phase Errors

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper presents the effect of carriers phase error on MC-CDMA performance in downlink mobile communications. Signal-to-Noise Ratio (SNR) and Bit-Error-Rate (BER) are analyzed taking into account the effect of carrier phase errors. It is shown that the MC-CDMA system is very sensitive to a carrier frequency offset, the system performance rapidly degrades and strongly depends on the number of carriers. For a maximal load, the degradation caused by carrier phase jitter is independent of the number of the carriers.

  17. [The normotensive carriers of the MTHFR 677T allele, displaying the increased risk of development of the abdominal aortic aneurysm (AAA), occur at the highest frequency among the smoking patients].

    Science.gov (United States)

    Strauss, Ewa; Waliszewski, Krzysztof; Pawlak, Andrzej L

    2004-01-01

    Abdominal aortic aneurysm (AAA) presents itself as a progressive dilation of the abdominal aorta, leading--if untreated--to rupture. It is a common disease of the elderly, with a complex etiology. Smoking, hypertension and several genetic factors are recognized as relevant for the pathogenesis of AAA. We studied association between the polymorphism of the MTHFR (methylenetetrahydrofolate reductase) gene within the fourth exon (677C>T) and the occurrence of hypertension and smoking status in the group of 74 male patients with AAA. In the patients group, the smoking hypertensive persons represented the largest subgroup (43%). We determined the the MTHFR 677C>T polymorphism in AAA patients and compared it to that in 71 healthy normotensive males. The frequencies of the 677T allele and MTHFR 677C>T genotypes were similar in both groups, but the subgroup of normotensive AAA patients (n=29) displayed significantly increased frequencies of 677T allele (0.4) and of 677CT and TT genotypes (69%), as compared to those in the control group (0.28 and 46%, respectively). This corresponds to the 3.3-fold greater risk of AAA in normotensive subjects with the 677T allele of MTHFR, as compared to the homo-zygotes 677CC (p<0.03; 95% CI=1.2-9.2). The highest frequencies of MTHFR 677T allele (0.43) and 677CT and TT genotypes (73%) were found in the subgroup of normotensive smoking patients (n=22).

  18. DESIGN OF WAVELET PACKET BASED MODEL FOR MULTI CARRIER MODULATION

    Directory of Open Access Journals (Sweden)

    MIHIR NARAYAN MOHANTY

    2012-04-01

    Full Text Available In current scenario Multi-Carrier modulation (MCM is considered an effective technique for both wire and wireless communications. It divides the entire bandwidth into several parallel sub-channels. This splitting is by dividing the transmit data into several parallel low-bit-rate data streams and then to modulate the carrierscorresponding to those sub-channels. Though MCM technique uses Orthogonal Frequency Division Multiplexing (OFDM model, it is very sensitive to Carrier Frequency Offset (CFO, that leads to a severedistortion in subcarrier orthogonality and causes inter channel interference (ICI. In this paper, Wavelet Packet Transform is designed for the model of MCM as a novel alternative to the most exiting Orthogonal Frequency Division Multiplexing (OFDM technique, because of its time frequency representation and lower side lobes intransmitted signals, that reduces inter carrier interference (ICI, and inter symbol interference (ISI. Performance analysis is investigated for such model. Simulation results show a significant enhancement in terms of spectral efficiency.

  19. Development of Passenger Air Carriers

    Directory of Open Access Journals (Sweden)

    Igor Diminik

    2006-09-01

    Full Text Available The work presents the development of carriers in passengerair traffic, and the focus is on the development and operationsof carriers in chartered passenger transport. After the SecondWorld War, there were only scheduled air carriers. The need formass transport of tourists resulted in the development of chartercarriers or usage of scheduled carriers under different commercialconditions acceptable for tourism. Eventually also low-costcarriers appeared and they realize an increasing share in thepassenger transport especially in the aviation developed countries.

  20. 47 CFR 80.375 - Radiodetermination frequencies.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Radiodetermination frequencies. 80.375 Section... SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Radiodetermination § 80.375 Radiodetermination frequencies. This section describes the carrier frequencies assignable to radiodetermination stations....

  1. Multiple frequency atmospheric radar techniques

    Science.gov (United States)

    Stitt, Gary Richard

    The use of multiple frequency coding to improve the vertical resolution of pulsed-Doppler very high frequency atmospheric radars, especially with regards to the two-frequency techniques known as frequency domain interferometry (FDI), is presented. This technique consists of transmitting alternate pulses on two distinct carrier frequencies. The two resulting time series are used to evaluate the normalized cross-correlation function, whose magnitude and phase are related to the thickness and position of a scattering layer. These same time series are also used to evaluate cross-spectra, which yield magnitude and phase values for each Doppler frequency component of the return signal.

  2. Maintainable substrate carrier for electroplating

    Science.gov (United States)

    Chen, Chen-An [Milpitas, CA; Abas, Emmanuel Chua [Laguna, PH; Divino, Edmundo Anida [Cavite, PH; Ermita, Jake Randal G [Laguna, PH; Capulong, Jose Francisco S [Laguna, PH; Castillo, Arnold Villamor [Batangas, PH; Ma,; Xiaobing, Diana [Saratoga, CA

    2012-07-17

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  3. Maintainable substrate carrier for electroplating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen-An; Abas, Emmanuel Chua; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor; Ma, Diana Xiaobing

    2016-08-02

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The carrier includes a non-conductive carrier body on which the substrates are placed and conductive lines embedded within the carrier body. A plurality of conductive clip attachment parts are attached in a permanent manner to the conductive lines embedded within the carrier body. A plurality of contact clips are attached in a removable manner to the clip attachment parts. The contact clips hold the substrates in place and conductively connecting the substrates with the conductive lines. Other embodiments, aspects and features are also disclosed.

  4. Glycosylation of solute carriers

    DEFF Research Database (Denmark)

    Pedersen, Nis Borbye; Carlsson, Michael C; Pedersen, Stine Helene Falsig

    2016-01-01

    as their posttranslational regulation, but only relatively little is known about the role of SLC glycosylation. Glycosylation is one of the most abundant posttranslational modifications of animal proteins and through recent advances in our understanding of protein-glycan interactions, the functional roles of SLC......Solute carriers (SLCs) are one of the largest groups of multi-spanning membrane proteins in mammals and include ubiquitously expressed proteins as well as proteins with highly restricted tissue expression. A vast number of studies have addressed the function and organization of SLCs as well...

  5. Terahertz transport dynamics of graphene charge carriers

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due

    The electronic transport dynamics of graphene charge carriers at femtosecond (10-15 s) to picosecond (10-12 s) time scales are investigated using terahertz (1012 Hz) time-domain spectroscopy (THz-TDS). The technique uses sub-picosecond pulses of electromagnetic radiation to gauge the electrodynamic...... response of thin conducting films at up to multi-terahertz frequencies. In this thesis THz-TDS is applied towards two main goals; (1) investigation of the fundamental carrier transport dynamics in graphene at femtosecond to picosecond timescales and (2) application of terahertz time-domain spectroscopy...... to rapid and non-contact electrical characterization of large-area graphene, relevant for industrial integration. We show that THz-TDS is an accurate and reliable probe of graphene sheet conductance, and that the technique provides insight into fundamental aspects of the nanoscopic nature of conduction...

  6. Nanostructured lipid carriers: versatile oral delivery vehicle.

    Science.gov (United States)

    Poonia, Neelam; Kharb, Rajeev; Lather, Viney; Pandita, Deepti

    2016-09-01

    Oral delivery is the most accepted and economical route for drug administration and leads to substantial reduction in dosing frequency. However, this route still remains a challenge for the pharmaceutical industry due to poorly soluble and permeable drugs leading to poor oral bioavailability. Incorporating bioactives into nanostructured lipid carriers (NLCs) has helped in boosting their therapeutic functionality and prolonged release from these carrier systems thus providing improved pharmacokinetic parameters. The present review provides an overview of noteworthy studies reporting impending benefits of NLCs in oral delivery and highlights recent advancements for developing engineered NLCs either by conjugating polymers over their surface or modifying their charge to overcome the mucosal barrier of GI tract for active transport across intestinal membrane.

  7. LIQUIFIED NATURAL GAS (LNG CARRIERS

    Directory of Open Access Journals (Sweden)

    Daniel Posavec

    2010-12-01

    Full Text Available Modern liquefied natural gas carriers are double-bottom ships classified according to the type of LNG tank. The tanks are specially designed to store natural gas cooled to -161°C, the boiling point of methane. Since LNG is highly flammable, special care must be taken when designing and operating the ship. The development of LNG carriers has begun in the middle of the twentieth century. LNG carrier storage space has gradually grown to the current maximum of 260000 m3. There are more than 300 LNG carriers currently in operation (the paper is published in Croatian.

  8. A digital instantaneous frequency measurement technique utilising high speed analogue to digital converters and field programmable gate arrays

    CSIR Research Space (South Africa)

    Herselman, PLR

    2007-09-01

    Full Text Available In modern information and sensor systems, the timely estimation of the carrier frequency of received signals is of critical importance. This paper presents a digital instantaneous frequency measurement (DIFM) technique, which can measure the carrier...

  9. GUI Application for ATCA-based LLRF Carrier Board Management

    CERN Document Server

    Wychowaniak, Jan; Predki, Pawel; Napieralski, Andrzej

    2011-01-01

    The Advanced Telecommunications Computing Architecture (ATCA) standard describes an efficient and powerful platform, implementation of which was adopted to be used as a base for control systems in high energy physics. The ATCA platform is considered to be applied for the X-ray Free Electron Laser (X-FEL), being built at Deutsches Electronen- Synchrotron (DESY) in Hamburg, Germany. The Low Level Radio Frequency (LLRF) control system is composed of a few ATCA Carrier Boards. Carrier Board hosts Intelligent Platform Management Controller (IPMC), which is developed in compliance with the PICMG specifications. IPMC is responsible for management and monitoring of sub-modules installed on Carrier Boards and pluggable Advanced Mezzanine Card (AMC) modules. The ATCA Shelf Manager is the main control unit of a single ATCA crate, responsible for all power and fan modules and Carrier Boards installed in ATCA shelf. The device provides a system administrator with a set of control and diagnostic capabilities regarding the ...

  10. The benefits of convergence.

    Science.gov (United States)

    Chang, Gee-Kung; Cheng, Lin

    2016-03-06

    A multi-tier radio access network (RAN) combining the strength of fibre-optic and radio access technologies employing adaptive microwave photonics interfaces and radio-over-fibre (RoF) techniques is envisioned for future heterogeneous wireless communications. All-band radio spectrum from 0.1 to 100 GHz will be used to deliver wireless services with high capacity, high link speed and low latency. The multi-tier RAN will improve the cell-edge performance in an integrated heterogeneous environment enabled by fibre-wireless integration and networking for mobile fronthaul/backhaul, resource sharing and all-layer centralization of multiple standards with different frequency bands and modulation formats. In essence, this is a 'no-more-cells' architecture in which carrier aggregation among multiple frequency bands can be easily achieved with seamless handover between cells. In this way, current and future mobile network standards such as 4G and 5G can coexist with optimized and continuous cell coverage using multi-tier RoF regardless of the underlying network topology or protocol. In terms of users' experience, the future-proof approach achieves the goals of system capacity, link speed, latency and continuous heterogeneous cell coverage while overcoming the bandwidth crunch in next-generation communication networks. © 2016 The Author(s).

  11. 42 CFR 421.200 - Carrier functions.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Carrier functions. 421.200 Section 421.200 Public...) MEDICARE PROGRAM MEDICARE CONTRACTING Carriers § 421.200 Carrier functions. A contract between CMS and a carrier specifies the functions to be performed by the carrier. The contract may include any or all of...

  12. Temporal modulation transfer functions obtained using sinusoidal carriers with normally hearing and hearing-impaired listeners.

    Science.gov (United States)

    Moore, B C; Glasberg, B R

    2001-08-01

    Temporal modulation transfer functions were obtained using sinusoidal carriers for four normally hearing subjects and three subjects with mild to moderate cochlear hearing loss. Carrier frequencies were 1000, 2000 and 5000 Hz, and modulation frequencies ranged from 10 to 640 Hz in one-octave steps. The normally hearing subjects were tested using levels of 30 and 80 dB SPL. For the higher level, modulation detection thresholds varied only slightly with modulation frequency for frequencies up to 80 Hz, but decreased for high modulation frequencies. The decrease can be attributed to the detection of spectral sidebands. For the lower level, thresholds varied little with modulation frequency for all three carrier frequencies. The absence of a decrease in the threshold for large modulation frequencies can be explained by the low sensation level of the spectral sidebands. The hearing-impaired subjects were tested at 80 dB SPL, except for two cases where the absolute threshold at the carrier frequency was greater than 70 dB SPL; in these cases a level of 90 dB was used. The results were consistent with the idea that spectral sidebands were less detectable for the hearing-impaired than for the normally hearing subjects. For the two lower carrier frequencies, there were no large decreases in threshold with increasing modulation frequency, and where decreases did occur, this happened only between 320 and 640 Hz. For the 5000-Hz carrier, thresholds were roughly constant for modulation frequencies from 10 to 80 or 160 Hz, and then increased monotonically, becoming unmeasurable at 640 Hz. The results for this carrier may reflect "pure" effects of temporal resolution, without any influence from the detection of spectral sidebands. The results suggest that temporal resolution for deterministic stimuli is similar for normally hearing and hearing-impaired listeners.

  13. Basic Stand Alone Carrier Line Items PUF

    Data.gov (United States)

    U.S. Department of Health & Human Services — This release contains the Basic Stand Alone (BSA) Carrier Line Items Public Use Files (PUF) with information from Medicare Carrier claims. The CMS BSA Carrier Line...

  14. Parallelized unscented Kalman filters for carrier recovery in coherent optical communication.

    Science.gov (United States)

    Jignesh, Jokhakar; Corcoran, Bill; Lowery, Arthur

    2016-07-15

    We show that unscented Kalman filters can be used to mitigate local oscillator phase noise and to compensate carrier frequency offset in coherent single-carrier optical communication systems. A parallel processing architecture implementing the unscented Kalman filter is proposed, improving upon a previous parallelized linear Kalman filter (LKF) implementation.

  15. Joint impact of quantization and clipping on single- and multi-carrier block transmission systems

    NARCIS (Netherlands)

    Yang, H.; Schenk, T.C.W.; Smulders, P.F.M.; Fledderus, E.R.

    2008-01-01

    This work investigates the joint impact of quantization and clipping, caused by analog-to-digital converters (ADCs) with low bit resolutions, on single- and multi-carrier block transmission systems in wireless multipath environments. We consider single carrier block transmission with frequency domai

  16. Content Distribution for Telecom Carriers

    Directory of Open Access Journals (Sweden)

    Ben Falchuk

    2006-08-01

    Full Text Available Distribution of digital content is a key revenue opportunity for telecommunications carriers. As media content moves from analog and physical media-based distribution to digital on-line distribution, a great opportunity exists for carriers to claim their role in the media value chain and grow revenue by enhancing their broadband “all you can eat” high speed Internet access offer to incorporate delivery of a variety of paid content. By offering a distributed peer to peer content delivery capability with authentication, personalization and payment functions, carriers can gain a larger portion of the revenue paid for content both within and beyond their traditional service domains. This paper describes an approach to digital content distribution that leverages existing Intelligent Network infrastructure that many carriers already possess, as well as Web Services.

  17. Methionine synthase A2756G and reduced folate carrier1 A80G ...

    African Journals Online (AJOL)

    Maha Moustafa

    2015-10-09

    Oct 9, 2015 ... folate carrier (RFC1) A80G gene polymorphisms on the maternal risk for DS. Patients: This study ..... To our knowledge, studies concerning the frequency of .... acid efficiency increases chromosomal instability, chromosome 21.

  18. 47 CFR 74.661 - Frequency tolerance.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Frequency tolerance. 74.661 Section 74.661... Stations § 74.661 Frequency tolerance. Stations in this service shall maintain the carrier frequency of... band(MHz) Frequency tolerance (%) 2,025 to 2,110 1 0.005 2,450 to 2,483.5 2 0.001 6,425 to 6,525...

  19. Optical Fibre Based Frequency Shifters Project

    Science.gov (United States)

    1991-01-28

    A fibre optic frequency shifter can be used to replace the Bragg cell acousto-optic modulator, currently used to generate low frequency optical...carriers, in fibre optic communications and sensor systems. This new form of frequency shifter, being an all fibre device, in which the propagating optical...large number of workers in recent years, (for example references [2-81 and those contained therein). The main elements of a fibre - optic frequency

  20. Carrier-phonon interaction in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Seebeck, Jan

    2009-03-10

    In recent years semiconductor quantum dots have been studied extensively due to their wide range of possible applications, predominantly for light sources. For successful applications, efficient carrier scattering processes as well as a detailed understanding of the optical properties are of central importance. The aims of this thesis are theoretical investigations of carrier scattering processes in InGaAs/GaAs quantum dots on a quantum-kinetic basis. A consistent treatment of quasi-particle renormalizations and carrier kinetics for non-equilibrium conditions is presented, using the framework of non-equilibrium Green's functions. The focus of our investigations is the interaction of carriers with LO phonons. Important for the understanding of the scattering mechanism are the corresponding quasi-particle properties. Starting from a detailed study of quantum-dot polarons, scattering and dephasing processes are discussed for different temperature regimes. The inclusion of polaron and memory effects turns out to be essential for the description of the carrier kinetics in quantum-dot systems. They give rise to efficient scattering channels and the obtained results are in agreement with recent experiments. Furthermore, a consistent treatment of the carrier-LO-phonon and the carrier-carrier interaction is presented for the optical response of semiconductor quantum dots, both giving rise to equally important contributions to the dephasing. Beside the conventional GaAs material system, currently GaN based light sources are of high topical interest due to their wide range of possible emission frequencies. In this material additionally intrinsic properties like piezoelectric fields and strong band-mixing effects have to be considered. For the description of the optical properties of InN/GaN quantum dots a procedure is presented, where the material properties obtained from an atomistic tight-binding approach are combined with a many-body theory for non

  1. Digital instantaneous frequency measurement technique utilising high-speed ADC’s and FPGA’s

    CSIR Research Space (South Africa)

    Herselman, PL

    2006-02-27

    Full Text Available This paper presents the Digital Instantaneous Frequency Measurement (DIFM) technique, which can measure the carrier frequency of a received waveform within a fraction of a microsecond. The resulting frequency range, resolution and accuracy...

  2. Widely Tunable Infrared Antennas Using Free Carrier Refraction.

    Science.gov (United States)

    Lewi, Tomer; Iyer, Prasad P; Butakov, Nikita A; Mikhailovsky, Alexander A; Schuller, Jon A

    2015-12-01

    We demonstrate tuning of infrared Mie resonances by varying the carrier concentration in doped semiconductor antennas. We fabricate spherical silicon and germanium particles of varying sizes and doping concentrations. Single-particle infrared spectra reveal electric and magnetic dipole, quadrupole, and hexapole resonances. We subsequently demonstrate doping-dependent frequency shifts that follow simple Drude models, culminating in the emergence of plasmonic resonances at high doping levels and long wavelengths. These findings demonstrate the potential for actively tuning infrared Mie resonances by optically or electrically modulating charge carrier densities, thus providing an excellent platform for tunable metamaterials.

  3. Addressing Carrier Aggregation with Narrow-band Tunable Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert F.

    2016-01-01

    Enhancing the operating bandwidth of antennas is particularly challenging when the antenna is confined in a very restricted volume, as is the case for mobile phones. However, increasing the bandwidth provides higher data rates to the users. Consequently, the carrier aggregation technology has been...... standardized. This paper proposes an antenna design that can address the bandwidth issue of new radio frequency standards, while coping with carrier aggregation requirements. Specifically, the paper presents a dual-antenna system, where each antenna exhibits a dual resonance. The low-bands of the radio...

  4. A Single Carrier Frequency Division Multiplex Access System Based on Discret Sine Transform and its Performance Analysis%基于离散正弦变换的单载波频分多址系统及其性能分析

    Institute of Scientific and Technical Information of China (English)

    周瑜; 庄陵; 邵凯; 王光宇

    2013-01-01

    To analyze the influence of Discrete Fourier Transform(DFT)and Discrete Sine Transform(DST)on the performance of a Single Carrier Frequency Division Multiple Access(SC-FDMA)system,a DST-based SC-FDMA system is introduced. The structure of SC-FDMA system based on DST is described. Then,the time do-main expressions of the DST IFDMA signal and DST LFDMA signal are derived and analyzed. Finally,the Peak-to-Average Power Ratio(PAPR)and impulse response of different pulse shaping filter are discussed. The simulation results show that the proposed DST SC-FDMA system has a better bit performance than the conven-tional DFT SC-FDMA and Orthogonal Frequency Division Multiple Access(OFDMA)system. Furthermore,the PAPR of DST SC-FDMA signals is closed to that of DFT SC-FDMA signals and lower than that of OFDMA.%  为分析离散傅里叶变换(DFT)与离散正弦变换(DST)对单载波频分多址(SC-FDMA)系统某些性能的影响,提出了一种基于离散正弦变换的单载波频分多址系统.给出了基于DST的SC-FD-MA系统的结构框图,接着重点推导和分析了DST IFDMA和DST LFDMA信号的时域表达式,最后讨论了系统的峰值平均功率比( PAPR)和不同脉冲成形滤波器的冲激响应.仿真结果表明,基于DST的SC-FDMA系统比传统的基于DFT的SC-FDMA系统和正交频分多址接入(OFDMA)系统有更好的比特误码率.此外,DST SC-FDMA信号的PAPR性能接近于DFT SC-FDMA且优于OFDMA.

  5. Carrier Phase Error Detection Method and Synchronization Control of Parallel-Connected PWM Inverters without Signal Line

    Science.gov (United States)

    Kohara, Tatsuya; Noguchi, Toshihiko; Kondo, Seiji

    In recent years, parallel-operation of inverters is employed to increase reliability and capacity in an uninterruptible power supply (UPS) system. A phase error in PWM carrier-signals of each inverter causes high frequency loop current between inverters. Therefore, the PWM carrier-signal of each inverter should be adjusted in phase. This paper proposes a detection method of phase error in PWM carrier-signal and its application to synchronization control for parallel-connected inverters. A simple definite-integral circuit achieves the detection of carrier phase error from high frequency loop current using no signal line between inverters. The detected carrier phase error is applied to synchronize the PWM carrier-signal through a PI-compensator, and then the high frequency loop current can be suppressed. Several experimental test-results show the validity of the proposed detection method and synchronization control.

  6. Bacterial Carriers for Glioblastoma Therapy

    Directory of Open Access Journals (Sweden)

    Nalini Mehta

    2017-03-01

    Full Text Available Treatment of aggressive glioblastoma brain tumors is challenging, largely due to diffusion barriers preventing efficient drug dosing to tumors. To overcome these barriers, bacterial carriers that are actively motile and programmed to migrate and localize to tumor zones were designed. These carriers can induce apoptosis via hypoxia-controlled expression of a tumor suppressor protein p53 and a pro-apoptotic drug, Azurin. In a xenograft model of human glioblastoma in rats, bacterial carrier therapy conferred a significant survival benefit with 19% overall long-term survival of >100 days in treated animals relative to a median survival of 26 days in control untreated animals. Histological and proteomic analyses were performed to elucidate the safety and efficacy of these carriers, showing an absence of systemic toxicity and a restored neural environment in treated responders. In the treated non-responders, proteomic analysis revealed competing mechanisms of pro-apoptotic and drug-resistant activity. This bacterial carrier opens a versatile avenue to overcome diffusion barriers in glioblastoma by virtue of its active motility in extracellular space and can lead to tailored therapies via tumor-specific expression of tumoricidal proteins.

  7. Low-cost carriers fare competition effect

    NARCIS (Netherlands)

    Carmona Benitez, R.B.; Lodewijks, G.

    2010-01-01

    This paper examines the effects that low-cost carriers (LCC’s) produce when entering new routes operated only by full-service carriers (FSC’s) and routes operated by low-cost carriers in competition with full-service carriers. A mathematical model has been developed to determine what routes should b

  8. Prospects of carrier screening of aspartylglucosaminuria in Finland.

    Science.gov (United States)

    Hietala, M; Grön, K; Syvänen, A C; Peltonen, L; Aula, P

    1993-01-01

    The frequency of carriers of the AGUFin mutation, the predominant mutation causing aspartylglucosaminuria in Finland, was determined in a population sample comprising 553 newborns from a delivery hospital in southern Finland, and 607 from a hospital in northern Finland. The AGUFin point mutation was identified from cord blood samples using the PCR-based, solid-phase minisequencing method. Nineteen carriers of the AGUFin mutation were detected, 8 (1:69) in the sample from the southern and 11 (1:55) from the northern population, respectively. The solid-phase minisequencing method proved to be rapid and convenient for the detection of the AGUFin mutation, and can readily be applied in large-scale carrier screening at the population level.

  9. Fast Frequency Offset Acquisition and Accurate Tracking in OFDM Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong-shan; ZHAO Ming; LIU Yuan-an

    2004-01-01

    A new carrier frequency offset estimation scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems is proposed. The carrier frequency offset estimation includes acquisition and tracking. The acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth. Comparison of the proposed scheme with Schmidl's algorithm by computer simulation illustrates the superior performance of the proposed scheme with regard to estimation accuracy in both AWGN channel and multipath channels.

  10. Hybrid nanostructured drug carrier with tunable and controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Depan, D.; Misra, R.D.K., E-mail: dmisra@louisiana.edu

    2012-08-01

    We describe here a transformative approach to synthesize a hybrid nanostructured drug carrier that exhibits the characteristics of controlled drug release. The synthesis of the nanohybrid architecture involved two steps. The first step involved direct crystallization of biocompatible copolymer along the long axis of the carbon nanotubes (CNTs), followed by the second step of attachment of drug molecule to the polymer via hydrogen bonding. The extraordinary inorganic-organic hybrid architecture exhibited high drug loading ability and is physically stable even under extreme conditions of acidic media and ultrasonic irradiation. The temperature and pH sensitive characteristics of the hybrid drug carrier and high drug loading ability merit its consideration as a promising carrier and utilization of the fundamental aspects used for synthesis of other promising drug carriers. The higher drug release response during the application of ultrasonic frequency is ascribed to a cavitation-type process in which the acoustic bubbles nucleate and collapse releasing the drug. Furthermore, the study underscores the potential of uniquely combining CNTs and biopolymers for drug delivery. - Graphical abstract: Block-copolymer crystallized on carbon nanotubes (CNTs). Nanohybrid drug carrier synthesized by attaching doxorubicin (DOX) to polymer crystallized CNTs. Crystallized polymer on CNTs provide mechanical stability. Triggered release of DOX. Highlights: Black-Right-Pointing-Pointer The novel synthesis of a hybrid nanostructured drug carrier is described. Black-Right-Pointing-Pointer The drug carrier exhibits high drug loading ability and is physically stable. Black-Right-Pointing-Pointer The high drug release is ascribed to a cavitation-type process.

  11. 75 FR 2923 - Motor Carrier Safety Advisory Committee Public Meeting

    Science.gov (United States)

    2010-01-19

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety Advisory Committee Meeting. SUMMARY: FMCSA announces that its Motor Carrier Safety Advisory Committee (MCSAC)...

  12. 75 FR 72863 - Motor Carrier Safety Advisory Committee Public Meeting

    Science.gov (United States)

    2010-11-26

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration, DOT. ACTION: Notice of Motor Carrier Safety Advisory Committee Meeting. SUMMARY: FMCSA announces that the Agency's Motor Carrier Safety Advisory Committee...

  13. 76 FR 12214 - Motor Carrier Safety Advisory Committee Public Meeting

    Science.gov (United States)

    2011-03-04

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration, DOT. ACTION: Notice: Announcement of Motor Carrier Safety Advisory Committee meeting; request for comment. SUMMARY: The Federal Motor Carrier Safety...

  14. 75 FR 29384 - Motor Carrier Safety Advisory Committee Public Meeting

    Science.gov (United States)

    2010-05-25

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety Advisory Committee meeting. SUMMARY: FMCSA announces that its Motor Carrier Safety Advisory Committee (MCSAC)...

  15. Comparison of methods to detect Pasteurella multocida in carrier waterfowl

    Science.gov (United States)

    Samuel, M.D.; Shadduck, D.J.; Goldberg, D.R.; Johnson, W.P.

    2003-01-01

    We conducted laboratory challenge trials using mallard ducks (Anas platyrhynchos) to compare methods for detecting carriers of Pasteurella multocida, the bacterium that causes avian cholera, in wild birds. Birds that survived the initial infection were euthanized at 2-4 wk intervals up to 14 wk post challenge. Isolates of P. multocida were obtained at necropsy from 23% of the birds that survived initial infection. We found that swab samples (oral, cloacal, nasal, eye, and leg joint) were most effective for detecting carrier birds up to 14 wk post infection. No detectable differences in isolation were observed for samples stored in either 10% dimethysulfoxide or brain heart infusion broth. The frequency of detecting carriers in our challenge trials appeared to be related to mortality rates observed during the trial, but was not related to a number of other factors including time after challenge, time delays in collecting tissues postmortem, and route of infection. In our trials, there was little association between antibody levels and carrier status. We concluded that swabs samples collected from recently dead birds, stored in liquid nitrogen, and processed using selective broth provide a feasible field method for detecting P. multocida carriers in wild waterfowl.

  16. ISS qualified thermal carrier equipment

    Science.gov (United States)

    Deuser, Mark S.; Vellinger, John C.; Jennings, Wm. M.

    2000-01-01

    Biotechnology is undergoing a period of rapid and sustained growth, a trend which is expected to continue as the general population ages and as new medical treatments and products are conceived. As pharmaceutical and biomedical companies continue to search for improved methods of production and, for answers to basic research questions, they will seek out new avenues of research. Space processing on the International Space Station (ISS) offers such an opportunity! Space is rapidly becoming an industrial laboratory for biotechnology research and processing. Space bioprocessing offers exciting possibilities for developing new pharmaceuticals and medical treatments, which can be used to benefit mankind on Earth. It also represents a new economic frontier for the private sector. For over eight years, the thermal carrier development team at SHOT has been working with government and commercial sector scientists who are conducting microgravity experiments that require thermal control. SHOT realized several years ago that the hardware currently being used for microgravity thermal control was becoming obsolete. It is likely that the government, academic, and industrial bioscience community members could utilize SHOT's hardware as a replacement to their current microgravity thermal carrier equipment. Moreover, SHOT is aware of several international scientists interested in utilizing our space qualified thermal carrier. SHOT's economic financing concept could be extremely beneficial to the international participant, while providing a source of geographic return for their particular region. Beginning in 2000, flight qualified thermal carriers are expected to be available to both the private and government sectors. .

  17. Design of Data Converters for Dual-carrier Orthogonal Frequency-Division Multiplexing Ultra-wideband System%适用于双载波-正交频分复用超宽带系统的数据转换器设计

    Institute of Scientific and Technical Information of China (English)

    夏杰峰; 哈钱钱; 林宇婧; 叶凡; 任俊彦

    2012-01-01

    Dual-carrier orthogonal frequency-division multiplexing (DC-OFDM) is adopted in China as the ultra-wideband (UWB) national standard. Two data converters are designed based on this UWB system standard, including a four-channel 650 MS/s 8 bit current-steering digital-to-analog converter (DAC) and a four- channel 300 MS/s 6 bit folding-and-interpolating analog-to-digital converter (ADC). Both of them are integrated on a printed circuit board (PCB). The DAC has focused on the matching of current sources and its dynamic performance is improved by reducing the voltage swing of the switch transistors. Testing result shows that one sub-DAC can achieve over 52 dB spurious-free dynamic range (SFDR) locating at 68 MHz input. The ADC adopts inter-stage pipelined switches to relax amplifiers' bandwidth, utilizes active interpolators to further mitigate the offset of the comparators and keeps the signal-to-noise-and-distortion ration (SNDR) of sub-ADC over 32 dB in the entire Nyquist band.%国家超宽带(UWB)标准采用了双载波-正交频分复用技术(DC-OFDM),此设计基于该标准的超宽带系统中用数据转换器,包括一个单片集成4通道650 MS/s 8 bit电流舵数模转换器(DAC)和一个单片集成4通道300 MS/s 6 bit折叠内插模数转换器(ADC),在印刷电路板(PCB)上实现集成.DAC设计着重考虑电流源的匹配,并且采用降摆幅电路提高动态性能,当输入频率为68 MHz时,单个子DAC无杂散动态范围(SFDR)可以达到51dB以上;ADC采用级间流水线开关降低放大器建立要求,采用有源内插进一步降低比较器失调影响,单个子ADC信噪失真比(SNDR)在整个奈奎斯特频带内都保持在32 dB以上.

  18. Hot carrier degradation in semiconductor devices

    CERN Document Server

    2015-01-01

    This book provides readers with a variety of tools to address the challenges posed by hot carrier degradation, one of today’s most complicated reliability issues in semiconductor devices.  Coverage includes an explanation of carrier transport within devices and book-keeping of how they acquire energy (“become hot”), interaction of an ensemble of colder and hotter carriers with defect precursors, which eventually leads to the creation of a defect, and a description of how these defects interact with the device, degrading its performance. • Describes the intricacies of hot carrier degradation in modern semiconductor technologies; • Covers the entire hot carrier degradation phenomenon, including topics such as characterization, carrier transport, carrier-defect interaction, technological impact, circuit impact, etc.; • Enables detailed understanding of carrier transport, interaction of the carrier ensemble with the defect precursors, and an accurate assessment of how the newly created defects imp...

  19. Targeted carrier screening for four recessive disorders: high detection rate within a founder population.

    Science.gov (United States)

    Mathijssen, Inge B; Henneman, Lidewij; van Eeten-Nijman, Janneke M C; Lakeman, Phillis; Ottenheim, Cecile P E; Redeker, Egbert J W; Ottenhof, Winnie; Meijers-Heijboer, Hanne; van Maarle, Merel C

    2015-03-01

    In a genetically isolated community in the Netherlands four severe recessive genetic disorders occur at relatively high frequency (pontocerebellar hypoplasia type 2 (PCH2), fetal akinesia deformation sequence (FADS), rhizomelic chondrodysplasia punctata type 1 (RCDP1), and osteogenesis imperfecta (OI) type IIB/III. Over the past decades multiple patients with these disorders have been identified. This warranted the start of a preconception outpatient clinic, in 2012, aimed at couples planning a pregnancy. The aim of our study was to evaluate the offer of targeted genetic carrier screening as a method to identify high-risk couples for having affected offspring in this high-risk subpopulation. In one year, 203 individuals (92 couples and 19 individuals) were counseled. In total, 65 of 196 (33.2%) tested individuals were carriers of at least one disease, five (7.7%) of them being carriers of two diseases. Carrier frequencies of PCH2, FADS, RCDP1, and OI were 14.3%, 11.2%, 6.1%, and 4.1% respectively. In individuals with a positive family history for one of the diseases, the carrier frequency was 57.8%; for those with a negative family history this was 25.8%. Four PCH2 carrier-couples were identified. Thus, targeted (preconception) carrier screening in this genetically isolated population in which a high prevalence of specific disorders occurs detects a high number of carriers, and is likely to be more effective compared to cascade genetic testing. Our findings and set-up can be seen as a model for carrier screening in other high-risk subpopulations and contributes to the discussion about the way carrier screening can be offered and organized in the general population.

  20. CaSCADE: Compressed Carrier and DOA Estimation

    OpenAIRE

    Stein, Shahar; Yair, Or; Cohen, Deborah; Eldar, Yonina C.

    2016-01-01

    Spectrum sensing and direction of arrival (DOA) estimation have been thoroughly investigated, both separately and as a joint task. Estimating the support of a set of signals and their DOAs is crucial to many signal processing applications, such as Cognitive Radio (CR). A challenging scenario, faced by CRs, is that of multiband signals, composed of several narrowband transmissions spread over a wide spectrum each with unknown carrier frequencies and DOAs. The Nyquist rate of such signals is hi...

  1. Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals

    Science.gov (United States)

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

    2014-05-20

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  2. Methods and apparatuses using filter banks for multi-carrier spread spectrum signals

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A.

    2016-06-14

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  3. Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals

    Science.gov (United States)

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

    2014-10-14

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  4. Methods and apparatuses using filter banks for multi-carrier spread spectrum signals

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

    2017-01-31

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  5. A Carrier Synchronization Algorithm for IEEE 802.11a System

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-guang; ZHOU Zheng

    2004-01-01

    A new Carrier Frequency Offset (CFO) estimation algorithm for IEEE 80211a system is proposed. The extended Kalman filter (EKF) is applied to estimate the frequency offset in the acquisition stage and the cyclic prefix (CP) is used to correct the residual CFO in the tracking stage. Simulation results demonstrate the super performance of the proposed algorithm compared to Maximum-Likelihood (ML) approach.

  6. Moving target detection for frequency agility radar by sparse reconstruction

    Science.gov (United States)

    Quan, Yinghui; Li, YaChao; Wu, Yaojun; Ran, Lei; Xing, Mengdao; Liu, Mengqi

    2016-09-01

    Frequency agility radar, with randomly varied carrier frequency from pulse to pulse, exhibits superior performance compared to the conventional fixed carrier frequency pulse-Doppler radar against the electromagnetic interference. A novel moving target detection (MTD) method is proposed for the estimation of the target's velocity of frequency agility radar based on pulses within a coherent processing interval by using sparse reconstruction. Hardware implementation of orthogonal matching pursuit algorithm is executed on Xilinx Virtex-7 Field Programmable Gata Array (FPGA) to perform sparse optimization. Finally, a series of experiments are performed to evaluate the performance of proposed MTD method for frequency agility radar systems.

  7. Fatigue reliability for LNG carrier

    Institute of Scientific and Technical Information of China (English)

    Xiao Taoyun; Zhang Qin; Jin Wulei; Xu Shuai

    2011-01-01

    The procedure of reliability-based fatigue analysis of liquefied natural gas (LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method (FEM). Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis, Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory, fatigue damage is characterized by an S-N relationship, and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.

  8. Preventative maintenance of straddle carriers

    Directory of Open Access Journals (Sweden)

    Si Li

    2015-02-01

    Full Text Available Background: Robotic vehicles such as straddle carriers represent a popular form of cargo handling amongst container terminal operators.Objectives: The purpose of this industry-driven study is to model preventative maintenance (PM influences on the operational effectiveness of straddle carriers.Method: The study employs historical data consisting of 21 273 work orders covering a 27-month period. Two models are developed, both of which forecast influences of PM regimes for different types of carrier.Results: The findings of the study suggest that the reliability of the straddle fleet decreases with increased intervals of PM services. The study also finds that three factors – namely resources, number of new straddles, and the number of new lifting work centres – influence the performances of straddles.Conclusion: The authors argue that this collaborative research exercise makes a significant contribution to existing supply chain management literature, particularly in the area of operations efficiency. The study also serves as an avenue to enhance relevant management practice.

  9. Robust GPS carrier tracking under ionospheric scintillation

    Science.gov (United States)

    Susi, M.; Andreotti, M.; Aquino, M. H.; Dodson, A.

    2013-12-01

    Small scale irregularities present in the ionosphere can induce fast and unpredictable fluctuations of Radio Frequency (RF) signal phase and amplitude. This phenomenon, known as scintillation, can degrade the performance of a GPS receiver leading to cycle slips, increasing the tracking error and also producing a complete loss of lock. In the most severe scenarios, if the tracking of multiple satellites links is prevented, outages in the GPS service can also occur. In order to render a GPS receiver more robust under scintillation, particular attention should be dedicated to the design of the carrier tracking stage, that is the receiver's part most sensitive to these types of phenomenon. This paper exploits the reconfigurability and flexibility of a GPS software receiver to develop a tracking algorithm that is more robust under ionospheric scintillation. For this purpose, first of all, the scintillation level is monitored in real time. Indeed the carrier phase and the post correlation terms obtained by the PLL (Phase Locked Loop) are used to estimate phi60 and S4 [1], the scintillation indices traditionally used to quantify the level of phase and amplitude scintillations, as well as p and T, the spectral parameters of the fluctuations PSD. The effectiveness of the scintillation parameter computation is confirmed by comparing the values obtained by the software receiver and the ones provided by a commercial scintillation monitoring, i.e. the Septentrio PolarxS receiver [2]. Then the above scintillation parameters and the signal carrier to noise density are exploited to tune the carrier tracking algorithm. In case of very weak signals the FLL (Frequency Locked Loop) scheme is selected in order to maintain the signal lock. Otherwise an adaptive bandwidth Phase Locked Loop (PLL) scheme is adopted. The optimum bandwidth for the specific scintillation scenario is evaluated in real time by exploiting the Conker formula [1] for the tracking jitter estimation. The performance

  10. 14 CFR Section 04 - Air Carrier Groupings

    Science.gov (United States)

    2010-01-01

    ... Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC... carrier to a specific group of carriers will be reviewed periodically by the Director, Office of Airline... Office of Airline Statistics will issue an updated listing of the carrier groups on an annual basis. A...

  11. Spacelab carrier complement thermal design and performance

    Science.gov (United States)

    Bancroft, S.; Key, R.; Kittredge, S.

    1992-01-01

    The present discussion of the Spacelab carrier complement, which encompasses a Module Carrier, a Module-Pallet Carrier, and a Multiplexer/Demultiplexer Pallet, gives attention to both active and passive thermal performance capabilities, and presents ground testing and analytical results obtained to date. An account is given of the prospective use of a Spacelab Multipurpose Experiment Support Structure.

  12. 7 CFR 33.4 - Carrier.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Carrier. 33.4 Section 33.4 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... ISSUED UNDER AUTHORITY OF THE EXPORT APPLE ACT Definitions § 33.4 Carrier. Carrier means any common...

  13. Frequency standards

    CERN Document Server

    Riehle, Fritz

    2006-01-01

    Of all measurement units, frequency is the one that may be determined with the highest degree of accuracy. It equally allows precise measurements of other physical and technical quantities, whenever they can be measured in terms of frequency.This volume covers the central methods and techniques relevant for frequency standards developed in physics, electronics, quantum electronics, and statistics. After a review of the basic principles, the book looks at the realisation of commonly used components. It then continues with the description and characterisation of important frequency standards

  14. Blood Pressure Levels in Male Carriers of Arg82Cys in CD300LG

    DEFF Research Database (Denmark)

    Støy, Julie; Grarup, Niels; Hørlyck, Arne

    2014-01-01

    (122 mmHg versus 115; p = 0.01) and diastolic blood pressure (77 mmHg versus 72; pgroups. Metalloproteinase-9 level was higher in CT-carriers than in CC-carriers (P... found to be associated with fasting HDL-cholesterol and triglyceride levels. The polymorphism has not been detected in hypertension GWAS potentially due to its low frequency, but CD300LG has been linked to blood pressure as CD300LG knockout mice have changes in blood pressure. Twenty......-four-hour ambulatory blood pressure was obtained in human CD300LG CT-carriers to follow up on these observations. METHODS: Twenty healthy male CD300LG rs72836561 CT-carriers matched for age and BMI with 20 healthy male CC-carriers. Office blood pressure, 24-hour ambulatory blood pressure, carotid intima...

  15. A Novel Ultra-Wide Band Signal Generation Scheme Based on Carrier Interference and Dynamics Suppression

    Directory of Open Access Journals (Sweden)

    Zhang Luyong

    2010-01-01

    Full Text Available This paper initiatively puts forward a novel synthesis design for generating UWB narrow pulse by using CI (Carrier Interference subcarrier waveform synthesis and Bessel function expansion. Through adaptively adjusting the initial phases of multiple sub-carriers according to the location information, CI (Carrier Interference sub-carrier waveform synthesis signal could achieve better performance. More specifically, when the carrier arrives at the receiver with a particular phase, the dynamic change of this signal amplitude can be significantly reduced by introducing sinusoidal frequency modulation signals. The method has significance for improving the overall performance of UWB communication system. This paper gives theoretical analysis and computer simulation results as well as the functional block diagram.

  16. Performance Analysis of Downlink Inter-band Carrier Aggregation in LTE-Advanced

    DEFF Research Database (Denmark)

    Wang, Hua; Rosa, Claudio; Pedersen, Klaus

    2011-01-01

    . With CA, it is possible to schedule a user equipment (UE) on multiple CCs simultaneously. From radio resource management (RRM) perspective, CC selection plays an important role in optimizing the system performance, especially in the case of inter-band CA where the radio propagation characteristics of each......Carrier aggregation (CA) is one of the most distinct features for LTE-Advanced systems, which can support a much wider transmission bandwidth up to 100 MHz by aggregating two or more individual component carriers (CCs) belonging to the same (intra-band) or different (inter-band) frequency bands...... CC can be different. In this paper, we investigate the downlink resource allocation for inter-band CA, i.e., how to assign carrier(s) to different UEs. A simple yet effective G-factor based carrier selection algorithm, which takes both traffic load and radio channel characteristics...

  17. 49 CFR 376.22 - Exemption for private carrier leasing and leasing between authorized carriers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Exemption for private carrier leasing and leasing... MOTOR CARRIER SAFETY REGULATIONS LEASE AND INTERCHANGE OF VEHICLES Exemptions for the Leasing Regulations § 376.22 Exemption for private carrier leasing and leasing between authorized carriers....

  18. A graphene based frequency quadrupler

    Science.gov (United States)

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

    2017-04-01

    Benefit from exceptional electrical transport properties, graphene receives worldwide attentions, especially in the domain of high frequency electronics. Due to absence of effective bandgap causing off-state the device, graphene material is extraordinarily suitable for analog circuits rather than digital applications. With this unique ambipolar behavior, graphene can be exploited and utilized to achieve high performance for frequency multipliers. Here, dual-gated graphene field-effect transistors have been firstly used to achieve frequency quadrupling. Two Dirac points in the transfer curves of the designed GFETs can be observed by tuning top-gate voltages, which is essential to generate the fourth harmonic. By applying 200 kHz sinusoid input, arround 50% of the output signal radio frequency power is concentrated at the desired frequency of 800 kHz. Additionally, in suitable operation areas, our devices can work as high performance frequency doublers and frequency triplers. Considered both simple device structure and potential superhigh carrier mobility of graphene material, graphene-based frequency quadruplers may have lots of superiorities in regards to ultrahigh frequency electronic applications in near future. Moreover, versatility of carbon material system is far-reaching for realization of complementary metal-oxide-semiconductor compatible electrically active devices.

  19. Frequency synthesiser

    NARCIS (Netherlands)

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram

    2016-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  20. Low-cost carriers fare competition effect

    OpenAIRE

    Carmona Benitez, R.B.; Lodewijks, G.

    2010-01-01

    This paper examines the effects that low-cost carriers (LCC’s) produce when entering new routes operated only by full-service carriers (FSC’s) and routes operated by low-cost carriers in competition with full-service carriers. A mathematical model has been developed to determine what routes should be operated by a low-cost carrier with better possibilities to subsist. The proposed model in this paper was set up by analyzing The United States domestic air transport market 2005 year database fr...

  1. Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors

    OpenAIRE

    Farmer, Damon B.; Chiu, Hsin-Ying; Lin, Yu-Ming; Jenkins, Keith A.; Xia, Fengnian; Avouris, Phaedon

    2009-01-01

    We utilize an organic polymer buffer layer between graphene and conventional gate dielectrics in top-gated graphene transistors. Unlike other insulators, this dielectric stack does not significantly degrade carrier mobility, allowing for high field-effect mobilities to be retained in top-gate operation. This is demonstrated in both two-point and four-point analysis, and in the high-frequency operation of a graphene transistor. Temperature dependence of the carrier mobility suggests that phono...

  2. Salmonella carriers among expatriate workers in Al-Qatif area

    Directory of Open Access Journals (Sweden)

    Albreiki Hassan

    2004-01-01

    Full Text Available Background: Salmonella infection and diarrhoeal diseases are major causes of morbidity and mortality in the developing world. All expatriates applying for work permits in the Kingdom of Saudi Arabia (KSA have to undergo a governmental compulsory health check program. Aim of the study: To estimate the number of salmonella carriers who had previously been diagnosed as free of infection. Subjects and methods: Over a period of two years, a total of 17, 918 workers in Al-Qatif area, in the Eastern Province were tested for salmonella on stool samples. Results: Three hundred and twenty eight were found to be asymptomatic carriers of salmonella. The highest frequency was found among workers from Egypt (13.1 % while Filipinos and Indians were the lowest carriers (1.2%. Salmonella serogroups E, C 1 and C2 were most common ( 29%, 29% and 23.5% respectively followed by serogroups B, D and C (13%, 3.7% and 1% respectively. No Shigella species were isolated. All carriers were given antibiotics and were instructed in prophylactic hygiene measures. After completing the course of antibiotics, they were retested and found to be clear of infection. Conclusion: The health check system in this area will contribute towards the prevention of outbreaks of infection by salmonella

  3. Robust frequency stabilization of multiple spectroscopy lasers with large and tunable offset frequencies.

    Science.gov (United States)

    Nevsky, A; Alighanbari, S; Chen, Q-F; Ernsting, I; Vasilyev, S; Schiller, S; Barwood, G; Gill, P; Poli, N; Tino, G M

    2013-11-15

    We have demonstrated a compact, robust device for simultaneous absolute frequency stabilization of three diode lasers whose carrier frequencies can be chosen freely relative to the reference. A rigid ULE multicavity block is employed, and, for each laser, the sideband locking technique is applied. A small lock error, computer control of frequency offset, wide range of frequency offset, simple construction, and robust operation are the useful features of the system. One concrete application is as a stabilization unit for the cooling and trapping lasers of a neutral-atom lattice clock. The device significantly supports and improves the clock's operation. The laser with the most stringent requirements imposed by this application is stabilized to a line width of 70 Hz, and a residual frequency drift less than 0.5 Hz/s. The carrier optical frequency can be tuned over 350 MHz while in lock.

  4. BER Performance of IEEE 802.11ad for Single Carrier and Multi Carrier

    Directory of Open Access Journals (Sweden)

    Abhishek Kumar Gupta

    2012-05-01

    Full Text Available In present scenario 802.11n is one of the fastest standards which is widely popular. It provides a theoretical maximum of 450 megabits per second (Mbps, with a typical throughput of 100Mbps. As we know, there is high demand for higher speed due to an increasing of high definition (HD video on smart phone usage and home entertainment. As 802.11n is not able to provide the required speed needed for these uses, thus there is need for technologies which can meet therequirement. IEEE 802.11ad is one of such standards which meet the requirement needed for the above. IEEE 802.11ad standard operates at 60 GHz frequency, promise to deliver from 1 to 7 Gbps. 60 GHz band is one of the largest unlicensed bandwidth with availability of at least 5 GHz of continuous bandwidth worldwide. In this paper we have tested the IEEE 802.11ad system model Bits Error Rate (BER for different modulation technique under several coding scheme for both Single Carrier and Multi Carriers. In this model the modulation technique mainly used are Binary Phase Shift Keying (BPSK, Quaternary Phase Shift Keying (QPSK, 16-Quadrature Amplitude Modulation (QAM, 64-Quadrature Amplitude Modulation (QAM and the coding scheme used is Low Density Parity Check (LDPC code with different code rate.

  5. Non-permeable substrate carrier for electroplating

    Energy Technology Data Exchange (ETDEWEB)

    Abas, Emmanuel Chua; Chen, Chen-An; Ma, Diana Xiaobing; Ganti, Kalyana Bhargava

    2012-11-27

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  6. Non-permeable substrate carrier for electroplating

    Energy Technology Data Exchange (ETDEWEB)

    Abas, Emmanuel Chua; Chen, Chen-an; Ma, Diana Xiaobing; Ganti, Kalyana; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor

    2015-12-29

    One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

  7. SMA carrier testing: a meta-analysis of differences in test performance by ethnic group.

    Science.gov (United States)

    MacDonald, William Kim; Hamilton, David; Kuhle, Stefan

    2014-12-01

    Spinal muscular atrophy (SMA) is a severe autosomal recessive genetic disease that occurs in about one in every 10 000 births. Prenatal carrier testing is available for SMA, and the utility of universal screening is actively debated. The aim of this study was to perform a systematic review and meta-analysis of SMA genotype frequency, carrier frequency, and carrier test performance in different ethnic groups. We performed a systematic review of the literature for studies on SMA carrier screening test performance. Ethnicity-specific allele frequencies, carrier rates, and screening test performance were determined from data of 169 000 individuals in 14 published studies. Pooled estimates were calculated for each ethnic group using a random effects meta-analysis. The detection rate of SMA screening in the non-Black population was 87-95%; however, detection rates fell to 71% among the Black population. These results highlight that although SMA carrier testing generally performs well and could be considered as a routine prenatal screen, SMA testing should be used cautiously in the Black population. © 2014 John Wiley & Sons, Ltd.

  8. At What Cost a Carrier?

    Science.gov (United States)

    2013-03-01

    brushed At What Cost a Carrier?M A R C H 2 0 1 3 4 | with interest, consequently pushing to convert the coal supply ship Jupiter into an American aircra...began to pay o!. By 1999 only 4 tons of bombs were needed to accomplish the mission, regardless of the weather at the target. Couple this fact with...there, how many bombs does it drop? | 7 #e &rst fact that needs to be understood in answer- ing these questions is that piloting an aircra" onto the

  9. Wuestite - a solar energy carrier

    Energy Technology Data Exchange (ETDEWEB)

    Weidenkaff, A.; Nueesch, P.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Reller, A. [Hamburg Univ., Hamburg (Germany)

    1997-06-01

    Hydrogen is produced when Wuestite (Fe{sub 1-y}O) is oxidised by water. This reaction is part of a two-step thermochemical metal oxide cycle for the storage of solar energy in the form of chemical energy carriers, characterised by a high chemical potential. The reaction was studied in a tubular furnace with on-line gas analysis and further characterised in detail by DTA und high-temperature X-ray powder diffraction. The influence of non-stoichiometry, morphology and temperature on the mechanism and kinetics of the water-splitting reaction was determined. (author) 3 figs., tabs., 3 refs.

  10. Hydrogen - A sustainable energy carrier

    Directory of Open Access Journals (Sweden)

    Kasper T. Møller

    2017-02-01

    Full Text Available Hydrogen may play a key role in a future sustainable energy system as a carrier of renewable energy to replace hydrocarbons. This review describes the fundamental physical and chemical properties of hydrogen and basic theories of hydrogen sorption reactions, followed by the emphasis on state-of-the-art of the hydrogen storage properties of selected interstitial metallic hydrides and magnesium hydride, especially for stationary energy storage related utilizations. Finally, new perspectives for utilization of metal hydrides in other applications will be reviewed.

  11. Radio-frequency transparent demodulation for broadband hybrid wireless-optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Sambaraju, Rakesh; Alemany, Ruben

    2010-01-01

    A novel demodulation technique which is transparent to radio-frequency (RF) carrier frequency is presented and experimentally demonstrated for multigigabit wireless signals. The presented demodulation technique employs optical single-sideband filtering, coherent detection, and baseband digital si...

  12. 78 FR 66801 - Motor Carrier Safety Advisory Committee; Charter Renewal

    Science.gov (United States)

    2013-11-06

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee; Charter Renewal AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Announcement of advisory... Committee that provides the Agency with advice and recommendations on motor carrier safety programs...

  13. Spread Spectrum Communication with Chaotic Frequency Modulation

    Science.gov (United States)

    Volkovskii, Alexander R.; Tsimring, Lev S.; Rulkov, Nikolai F.; Langmore, Ian; Young, Stephen C.

    We describe two different approaches to employ chaotic signals in spread-spectrum (SS) communication systems with phase and frequency modulation. In the first one a chaotic signal is used as a carrier. We demonstrate that using a feedback loop controller, the local chaotic oscillator in the receiver can be synchronized to the transmitter. The information can be transmitted using phase or frequency modulation of the chaotic carrier signal. In the second system the chaotic signal is used for frequency modulation of a voltage controlled oscillator (VCO) to provide a SS signal similar to frequency hopping systems. We show that in a certain parameter range the receiver VCO can be synchronized to the transmitter VCO using a relatively simple phase lock loop (PLL) circuit. The same PLL is used for synchronization of the chaotic oscillators. The information signal can be transmitted using a binary phase shift key (BPSK) or frequency shift key (BFSK) modulation of the frequency modulated carrier signal. Using an experimental circuit operating at radio frequency band and a computer modeling we study the bit error rate (BER) performance in a noisy channel as well as multiuser capability of the system.

  14. Frequency conversion of structured light.

    Science.gov (United States)

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

    2016-02-15

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

  15. Carrier Bulk-Lifetime Measurements

    Directory of Open Access Journals (Sweden)

    M. Solcansky

    2012-01-01

    Full Text Available For the measurement of the minority carrier bulk-lifetime the characterization method MW-PCD is used, where the result of measurement is the effective carrier lifetime, which is very dependent on the surface recombination velocity and therefore on the quality of a silicon surface passivation. This work deals with an examination of a different solution types for the chemical passivation of a silicon surface. Various solutions are tested on silicon wafers for their consequent comparison. The main purpose is to find optimal solution, which suits the requirements of a time stability and start-up velocity of passivation, reproducibility of the measurements and a possibility of a perfect cleaning of a passivating solution remains from a silicon surface, so that the parameters of a measured silicon wafer will not worsen and there will not be any contamination of the other wafers series in the production after a repetitive return of the measured wafer into the production process. The cleaning process itself is also a subject of a development.

  16. Apparatus and methods of measuring minority carrier lifetime using a liquid probe

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian

    2016-04-12

    Methods and apparatus for measuring minority carrier lifetimes using liquid probes are provided. In one embodiment, a method of measuring the minority carrier lifetime of a semiconductor material comprises: providing a semiconductor material having a surface; forming a rectifying junction at a first location on the surface by temporarily contacting the surface with a conductive liquid probe; electrically coupling a second junction to the semiconductor material at a second location, wherein the first location and the second location are physically separated; applying a forward bias to the rectifying junction causing minority carrier injection in the semiconductor material; measuring a total capacitance as a function of frequency between the rectifying junction and the second junction; determining an inflection frequency of the total capacitance; and determining a minority lifetime of the semiconductor material from the inflection frequency.

  17. Silicon ball grid array chip carrier

    Science.gov (United States)

    Palmer, David W.; Gassman, Richard A.; Chu, Dahwey

    2000-01-01

    A ball-grid-array integrated circuit (IC) chip carrier formed from a silicon substrate is disclosed. The silicon ball-grid-array chip carrier is of particular use with ICs having peripheral bond pads which can be reconfigured to a ball-grid-array. The use of a semiconductor substrate such as silicon for forming the ball-grid-array chip carrier allows the chip carrier to be fabricated on an IC process line with, at least in part, standard IC processes. Additionally, the silicon chip carrier can include components such as transistors, resistors, capacitors, inductors and sensors to form a "smart" chip carrier which can provide added functionality and testability to one or more ICs mounted on the chip carrier. Types of functionality that can be provided on the "smart" chip carrier include boundary-scan cells, built-in test structures, signal conditioning circuitry, power conditioning circuitry, and a reconfiguration capability. The "smart" chip carrier can also be used to form specialized or application-specific ICs (ASICs) from conventional ICs. Types of sensors that can be included on the silicon ball-grid-array chip carrier include temperature sensors, pressure sensors, stress sensors, inertia or acceleration sensors, and/or chemical sensors. These sensors can be fabricated by IC processes and can include microelectromechanical (MEM) devices.

  18. Carrier-envelope Phase Drift Detection of Picosecond Pulses

    Directory of Open Access Journals (Sweden)

    Cormier E.

    2013-03-01

    Full Text Available A bandwidth-independent, linear and scalable method for carrier-envelope phase drift measurement demonstrated. Our experiments reveal that carrier-envelope phase drift of a picosecond pulse train can be directly obtained from the spectrally resolved interference pattern of a length-stabilized multiple-beam interferometer. The retrieved phase from the pattern correlates well with the strongly CEP-sensitive coupling signal between the frequency combs of the picosecond oscillator and an ultra-high finesse Fabry-Perot interferometer. Our results can lead to the generation of a robust CEP-stabilized seed pulse train for high resolution comb spectroscopy as well as to compact Compton X-ray and gamma-ray sources

  19. Efficient Parallel Carrier Recovery for Ultrahigh Speed Coherent QAM Receivers with Application to Optical Channels

    Directory of Open Access Journals (Sweden)

    Pablo Gianni

    2013-01-01

    Full Text Available This work presents a new efficient parallel carrier recovery architecture suitable for ultrahigh speed intradyne coherent optical receivers (e.g., ≥100 Gb/s with quadrature amplitude modulation (QAM. The proposed scheme combines a novel low-latency parallel digital phase locked loop (DPLL with a feedforward carrier phase recovery (CPR algorithm. The new low-latency parallel DPLL is designed to compensate not only carrier frequency offset but also frequency fluctuations such as those induced by mechanical vibrations or power supply noise. Such carrier frequency fluctuations must be compensated since they lead to higher phase error variance in traditional feedforward CPR techniques, significantly degrading the receiver performance. In order to enable a parallel-processing implementation in multigigabit per second receivers, a new approximation to the DPLL computation is introduced. The proposed technique reduces the latency within the feedback loop of the DPLL introduced by parallel processing, while at the same time it provides a bandwidth and capture range close to those achieved by a serial DPLL. Simulation results demonstrate that the effects caused by frequency deviations can be eliminated with the proposed low latency parallel carrier recovery architecture.

  20. Differential Analysis of the Nasal Microbiome of Pig Carriers or Non-Carriers of Staphylococcus aureus

    DEFF Research Database (Denmark)

    Espinosa-Gongora, Carmen; Larsen, Niels; Schonning, Kristian;

    2016-01-01

    pathogen in animal carriers. The aim of this study was to determine whether the nasal microbiome of pig S. aureus carriers differs from that of non-carriers. The V3-V5 region of the 16S rRNA gene was sequenced from nasal swabs of 44 S. aureus carriers and 56 non-carriers using the 454 GS FLX titanium...... microbiome of pigs that are not colonized with S. aureus harbours several species/taxa that are significantly less abundant in pig carriers, suggesting that the nasal microbiota may play a role in the individual predisposition to S. aureus nasal carriage in pigs. Further research is warranted to isolate...

  1. Carriers of the astronomical 2175 ? extinction feature

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, J; Dai, Z; Ernie, R; Browning, N; Graham, G; Weber, P; Smith, J; Hutcheon, I; Ishii, H; Bajt, S; Floss, C; Stadermann, F

    2004-07-20

    The 2175 {angstrom} extinction feature is by far the strongest spectral signature of interstellar dust observed by astronomers. Forty years after its discovery the origin of the feature and the nature of the carrier remain controversial. The feature is enigmatic because although its central wavelength is almost invariant its bandwidth varies strongly from one sightline to another, suggesting multiple carriers or a single carrier with variable properties. Using a monochromated transmission electron microscope and valence electron energy-loss spectroscopy we have detected a 5.7 eV (2175 {angstrom}) feature in submicrometer-sized interstellar grains within interplanetary dust particles (IDPs) collected in the stratosphere. The carriers are organic carbon and amorphous silicates that are abundant and closely associated with one another both in IDPs and in the interstellar medium. Multiple carriers rather than a single carrier may explain the invariant central wavelength and variable bandwidth of the astronomical 2175 {angstrom} feature.

  2. Impact of carriers in oral absorption

    DEFF Research Database (Denmark)

    Gram, Luise Kvisgaard; Rist, Gerda Marie; Lennernäs, Hans

    2009-01-01

    (APP) was not described by carrier kinetics. However, glipizide is affecting exsorption for ES, due to interactions on basolateral carrier. The study confirms that estrone-3-sulfate can be used to characterize anionic carrier kinetics. Furthermore it is suggested that estrone-3-sulfate may be used to identify compounds......Carriers may mediate the permeation across enterocytes for drug substances being organic anions. Carrier mediated permeation for the organic anions estrone-3-sulfate (ES) and glipizide across Caco-2 cells were investigated kinetically, and interactions on involved carriers evaluated. Initial...... uptakes (P(UP)) at apical and basolateral membranes, apparent permeabilities (P(APP)) and corresponding intracellular end-point accumulations (P(EPA)) of radioactive labeled compounds were studied. Possible effects of other anionic compounds were investigated. Apical P(UP) and absorptive P(APP) for ES...

  3. Ultrafast carriers dynamics in filled-skutterudites

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liang; Xu, Xianfan, E-mail: xxu@purdue.edu [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Salvador, James R. [Chemical and Materials Systems Laboratory, GM Global R and D, Warren, Michigan 48090 (United States)

    2015-06-08

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4–0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  4. Ultrafast carriers dynamics in filled-skutterudites

    Science.gov (United States)

    Guo, Liang; Xu, Xianfan; Salvador, James R.

    2015-06-01

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4-0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  5. New Dimensions of Moving Bed Biofilm Carriers

    OpenAIRE

    Piculell, Maria

    2016-01-01

    The moving bed biofilm reactor (MBBR) is a biological wastewater treatment process in which microorganisms grow as biofilms on suspended carriers. Conventionally, MBBRs are mainly designed and optimized based on the carrier surface area, neglecting the dynamic relationship between carrier design, reactor operation and biofilm characteristics, such as biofilm thickness and the composition of the microbial community. The purpose of this research project was to learn more about the roles of the ...

  6. Distributed optical multiplexing with precise frequency allocation using fiber frequency conversion

    Science.gov (United States)

    Kato, Tomoyuki; Okabe, Ryo; Watanabe, Shigeki

    2013-12-01

    Effective utilization of fiber capacity in optical communication networks is required to keep up with the increasing traffic demand. Precise optical frequency allocation among carriers is essential for improving the spectral efficiency to utilize the limited spectral resource. In this paper, we show a distributed optical multiplexing scheme, in which data signals are sequentially multiplexed by frequency-division multiplexing on a single-wavelength optical carrier using fiber frequency conversion with locally provided optical subcarrier signals. The scheme achieves dense packing of distributed multi-channel signals with precise frequency allocation using free-running lasers. Using the scheme we demonstrate a precise multiplexing of coherent-optical orthogonal frequency-division multiplexing and Nyquist wavelength-division multiplexing.

  7. Carriers by chemical vapor deposition

    Science.gov (United States)

    Mronga, Norbert; Adel, J.; Czech, Erwin

    1990-07-01

    Printed materials are affecting people's lives in a variety of ways and to a constantly increasing extent, both in the private and in the business spheres. In particular, the predicted reduction of printed materials resulting from electronic data processing - the so-called "paperless electronic office" - has not occured, indeed quite the reverse. In recent years electrophotographic reprography has established itself successfully as a competitor to conventional printing processes. In the office a photocopier is now a part of the standard equipment. Because of BASF's traditional intensive involvement with pigments and colored printing inks its interest in new technologies in these areas is especially great. BASF has therefore been engaged in research on carriers for some years now.

  8. Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion

    Science.gov (United States)

    Kamaraju, N.; Kumar, Sunil; Anija, M.; Sood, A. K.

    2010-11-01

    We report femtosecond time-resolved reflectivity measurements of coherent phonons in tellurium performed over a wide range of temperatures (3-296 K) and pump-laser intensities. A totally symmetric A1 coherent phonon at 3.6 THz responsible for the oscillations in the reflectivity data is observed to be strongly positively chirped (i.e., phonon time period decreases at longer pump-probe delay times) with increasing photoexcited carrier density, more so at lower temperatures. We show that the temperature dependence of the coherent phonon frequency is anomalous (i.e, increasing with increasing temperature) at high photoexcited carrier density due to electron-phonon interaction. At the highest photoexcited carrier density of ˜1.4×1021cm-3 and the sample temperature of 3 K, the lattice displacement of the coherent phonon mode is estimated to be as high as ˜0.24Å . Numerical simulations based on coupled effects of optical absorption and carrier diffusion reveal that the diffusion of carriers dominates the nonoscillatory electronic part of the time-resolved reflectivity. Finally, using the pump-probe experiments at low carrier density of 6×1018cm-3 , we separate the phonon anharmonicity to obtain the electron-phonon coupling contribution to the phonon frequency and linewidth.

  9. Difference-frequency combs in cold atom physics

    CERN Document Server

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

    2016-01-01

    Optical frequency combs provide the clockwork to relate optical frequencies to radio frequencies. Hence, combs allow to measure optical frequencies with respect to a radio frequency where the accuracy is limited only by the reference signal. In order to provide a stable link between the radio and optical frequencies, the two parameters of the frequency comb must be fixed: the carrier envelope offset frequency $f_{\\rm ceo}$ and the pulse repetition-rate $f_{\\rm rep}$. We have developed the first optical frequency comb based on difference frequency generation (DFG) that eliminates $f_{\\rm ceo}$ by design - specifically tailored for applications in cold atom physics. An $f_{\\rm ceo}$-free spectrum at 1550 nm is generated from a super continuum spanning more than an optical octave. Established amplification and frequency conversion techniques based on reliable telecom fiber technology allow generation of multiple wavelength outputs. In this paper we discuss the frequency comb design, characterization, and optical...

  10. THE DIFFUSE INTERSTELLAR BANDS AND ANOMALOUS MICROWAVE EMISSION MAY ORIGINATE FROM THE SAME CARRIERS

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, L. S.; Cline, J. A. [Spectral Sciences, Inc., 4 Fourth Avenue, Burlington, MA 01803 (United States); Clark, F. O. [Wopeco Research 125 South Great Road, Lincoln, MA 01773 (United States); Lynch, D. K., E-mail: larry@spectral.com, E-mail: jcline@spectral.com, E-mail: frank.clark@gmail.com, E-mail: dave@thulescientific.com [Thule Scientific, P.O. Box 953, Topanga, CA 90290 (United States)

    2015-11-10

    We argue that the observed spectroscopic and statistical properties of the diffuse interstellar band (DIB) carriers are those that are needed to produce the anomalous microwave emission (AME). We explore this idea using a carrier-impartial model for AME based on the observed DIB statistical properties. We show that an observed distribution of profile widths for narrow DIBs can be mapped into an AME spectrum. The mapping model is applied to width distributions observed for HD 204827 and HD 183143, selected because their spectroscopic and statistical properties bracket those for most other sight lines. The predicted AME spectra for these sight lines agree well with the range of spectral shapes, and peak frequencies, ∼23–31 GHz, typically observed for AME. We use the AME spectral profiles to derive a strong constraint between the average carrier size and its rotational temperature. The constraint is applied to a variety of postulated molecular carrier classes, including polycyclic aromatic hydrocarbons, fulleranes, hydrocarbon chains, and amorphous hydrocarbon clusters. The constraint favors small, cold carriers with average sizes of ∼8–15 carbon atoms, and average rotational temperatures of ∼3–10 K, depending on carrier type. We suggest new observations, analyses, and modeling efforts to help resolve the ambiguities with regard to carrier size and class, and to further clarify the DIB–AME relationship.

  11. 14 CFR 399.82 - Passing off of carrier identity by affiliation between carriers.

    Science.gov (United States)

    2010-01-01

    ... carrier shall not engage in joint public relations activities at points served by both carriers which tend... specified area or point, in relation to services such as the following: Solicitation and sale of passenger... name of the other carrier as to emphasize the limited role of the agent; (4) Telephone facilities at...

  12. Assessment of GPS carrier-phase stability for time-transfer applications.

    Science.gov (United States)

    Larson, K M; Levine, J; Nelson, L M; Parker, T E

    2000-01-01

    We have conducted global positioning system (GPS) carrier-phase time-transfer experiments between the master clock (MC) at the U.S. Naval Observatory (USNO) in Washington, DC and the alternate master clock (AMC) at Schriever Air Force Base near Colorado Springs, Colorado. These clocks are also monitored on an hourly basis with two-way satellite time-transfer (TWSTT) measurements. We compared the performance of the GPS carrier phase and TWSTT systems over a 236-d period. Because of power problems and data outages during the carrier-phase experiment, the longest continuous time span is 96 d. The data from this period show agreement with TWSTT within +/-1 ns, apart from an overall constant time offset (caused by unknown delays in the GPS hardware at both ends). For averaging times of a day, the carrier-phase and TWSTT systems have a frequency uncertainty of 2.5 and 5.5 parts in 10(15), respectively.

  13. Statistical characteristics of L1 carrier phase observations from four low-cost GPS receivers

    DEFF Research Database (Denmark)

    Cederholm, Jens Peter

    2010-01-01

    Statistical properties of L1 carrier phase observations from four low-cost GPS receivers are investigated through a case study. The observations are collected on a zero baseline with a frequency of 1 Hz and processed with a double difference model. The carrier phase residuals from an ambiguity...... mean value close to zero and the sample variance is time invariant. The residuals from one type of receiver deviate from being normally distributed, whereas the residuals from the remaining receivers are close to being normally distributed. Two of the receivers deliver uncorrelated carrier phase...... observations. Some of the carrier phase observations from the other two receivers are serially correlated. The correlation is receiver specific and is related to the individual channels of the receivers....

  14. 5 CFR 890.1308 - Carrier participation.

    Science.gov (United States)

    2010-01-01

    ... 890.1308 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES HEALTH BENEFITS PROGRAM Department of Defense Federal Employees Health Benefits Program Demonstration Project § 890.1308 Carrier participation. (a) All carriers who participate in the...

  15. Providing resilience for carrier ethernet multicast traffic

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2009-01-01

    This paper presents an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we detail how multicast traffic, which is essential for e.g. IPTV can be protected. We present Carrier Ethernet resilience methods for linear and ring networks and show by simulation...... that the availability of a multicast connection can be significantly increased by applying relevant resilience techniques....

  16. Providing resilience for carrier ethernet multicast traffic

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2009-01-01

    This paper presents an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we detail how multicast traffic, which is essential for e.g. IPTV can be protected. We present Carrier Ethernet resilience methods for linear and ring networks and show by simulation...

  17. Protection switching for carrier ethernet multicast

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Berger, Michael Stübert

    2010-01-01

    This paper addresses network survivability for IPTV multicast transport in Carrier Ethernet networks. The impact of link failures is investigated and suggestions for intelligent multicast resilience schemes are proposed. In particular, functions of the multicast tree are integrated with the Carrier...

  18. Preparation and application of functionalized nano drug carriers

    Directory of Open Access Journals (Sweden)

    Rudong Gong

    2016-05-01

    Full Text Available Objective: Targeting at category memory characteristics and preparation methods of functionalized nano drugs, preparation technology of functionalized nano drug carriers is studied, and then important role of functionalized nano drug carrier in preparation of medicine is studied. Methods: Carry out the relevant literature search with computer, change limited language in the paper to Chinese and necessarily remove repetitive studies. Results: After first review of 1260 retrieved literature, it can be found that nano drug is with accurate quantity, relatively good targeting, specificity and absorbency. Necessary research of nano drug carriers can prevent and treat disease to a certain extent. Conclusion: Preparation of functionalized nanocarrier is simple and convenient, which can improve frequency of use of nano preparation technology and provide better development space for medical use. Therefore, nanocarriers should be combined with drugs with relatively strong specificity in clinics, in order to be able to conduct effective research on nanometer intelligent drug, effectively promote long-term development of nano biotechnology, and then provide favorable, reliable basis for clinical diagnosis and treatment.

  19. Multi-carrier Modulation (MCM) Signaling using OFDM Technique

    Science.gov (United States)

    Umadevi, H.; Gowda, Chandrakanth H.; Gurumurthy, K. S.

    2011-12-01

    OFDM is novel multicarrier modulation (MCM) technique. It has strong advantage of being a generic transmission scheme whose actual characteristics can be widely customized to fulfill several requirements and constraints of an advanced communication system. It adopts wavelet packet function as carriers which have the characteristic of good orthogonality and time-frequency localization. It can be seen from both theoretical analysis and software simulation that multi-carrier modulation and demodulation technique based on wavelet packet transform has unique advantage and great potential in improving the performance of communication system. This paper demonstrates the operation of a Wavelet Packet based multi-carrier modulation (WP-MCM) scheme. The wavelet packets are derived from multistage tree-structured paraunitary filter banks by choosing the right tree structure which would minimize the bit error between the desired and received signal for a particular channel condition. The performance of the system is simulated and analyzed for the AWGN channel. Through simulation results, we demonstrate the efficacy and the flexibility of the proposed wavelet packet based mechanism. The Bit Error rate (BER) performance is shown to be comparable, and even at times better, to conventional Fourier based OFDM. Comparison of different family of wavelets has been carried out and Meyer wavelet seems to be the most suitable wavelet through simulation results.

  20. The Kinetics of Carrier Transport Inhibition

    DEFF Research Database (Denmark)

    Rosenberg, T.; Wilbrandt, Robert Walter

    1962-01-01

    The kinetical treatment of enzymatic carrier transports as given in previous communications has been extended to conditions of inhibition. Various possible types of inhibitors have been considered differing in the site of attack (enzyme or carrier), in the mode of action (competing...... with the substrate for the enzyme or the carrier or for both, competing with the carrier for the enzyme, or non-competitive) and in the ability of penetrating the membrane. Experiments are reported on the inhibition of glucose and fructose transport across the human red cell membrane by phlorizine, phloretine...... the first order asymmetry severalfold (“second order asymmetry”). It was shown that a substrate competitive mode of action involving competition both for the enzyme and for the enzyme-bound carrier will result in a behaviour resembling the observed “second order asymmetry”. It is felt, therefore...

  1. Modeling of Carrier Dynamics in Electroabsorption Modulators

    DEFF Research Database (Denmark)

    Højfeldt, Sune

    2002-01-01

    and a phenomenological model for the carrier sweep-out dynamics, we investigate all-optical wavelength conversion, all-optical signal regeneration, and all-optical demultiplexing. A detailed drift-diffusion type model for the sweerp-out of photo-excited carriers in electroabsorption modulators is presented. We use...... the model to calclulate absorption spectra and steady-state carrier distributions in different modulator structures. This allows us to investigate a number of important properties of electroabsorption modulators, such as the electroabsorption effect and th saturation properties. We also investigate...... the influence that carrier recapture has on the device properties, and we discuss the recapture process on a more fundamental level. The model is also used to investigate in detail the carrier sweep-out process in electroabsorption modulators. We investigate how the intrinsic-region width, the separate...

  2. A novel mutation in the HEXA gene specific to Tay-Sachs disease carriers of Jewish Iraqi origin.

    Science.gov (United States)

    Karpati, M; Peleg, L; Gazit, E; Akstein, E; Goldman, B

    2000-05-01

    An increased frequency of carriers of 1:140, as defined by reduced hexosaminidase A (HexA) activity, was observed among Iraqi Jews participating in the Tay-Sachs disease (TSD) carrier detection program. Prior to this finding, TSD among Jews had been restricted to those of Eastern European (Ashkenazi) and Moroccan descent with carrier frequencies of 1:29 and 1:110 for Jews of Ashkenazi and Moroccan extraction, respectively. A general, pan-ethnic frequency of approximately 1:280 has been observed among other Jewish Israeli populations. Analysis of 48 DNA samples from Iraqi Jews suspected, by enzymatic assay, to be carriers revealed a total of five mutations, one of which was novel. In nine carriers (19%), a known mutation typical to either Ashkenazi or Moroccan Jews was identified. DeltaF304/ 305 was detected in four individuals, and + 1278TATC in three. G269S and R170Q each appeared in a single person. The new mutation, G749T, resulting in a substitution of glycine to valine at position 250 has been found in 19 of the DNA samples (40%). This mutation was not detected among 100 non-carrier, Iraqi Jews and 65 Ashkenazi enzymatically determined carriers. Aside from Ashkenazi and Moroccan Jews, a specific mutation in the HEXA gene has now also been identified in Jews of Iraqi descent.

  3. Pan-ethnic carrier screening and prenatal diagnosis for spinal muscular atrophy: clinical laboratory analysis of >72,400 specimens.

    Science.gov (United States)

    Sugarman, Elaine A; Nagan, Narasimhan; Zhu, Hui; Akmaev, Viatcheslav R; Zhou, Zhaoqing; Rohlfs, Elizabeth M; Flynn, Kerry; Hendrickson, Brant C; Scholl, Thomas; Sirko-Osadsa, Deborah Alexa; Allitto, Bernice A

    2012-01-01

    Spinal muscular atrophy (SMA) is a leading inherited cause of infant death with a reported incidence of ~1 in 10,000 live births and is second to cystic fibrosis as a common, life-shortening autosomal recessive disorder. The American College of Medical Genetics has recommended population carrier screening for SMA, regardless of race or ethnicity, to facilitate informed reproductive options, although other organizations have cited the need for additional large-scale studies before widespread implementation. We report our data from carrier testing (n = 72,453) and prenatal diagnosis (n = 121) for this condition. Our analysis of large-scale population carrier screening data (n = 68,471) demonstrates the technical feasibility of high throughput testing and provides mutation carrier and allele frequencies at a level of accuracy afforded by large data sets. In our United States pan-ethnic population, the calculated a priori carrier frequency of SMA is 1/54 with a detection rate of 91.2%, and the pan-ethnic disease incidence is calculated to be 1/11,000. Carrier frequency and detection rates provided for six major ethnic groups in the United States range from 1/47 and 94.8% in the Caucasian population to 1/72 and 70.5% in the African American population, respectively. This collective experience can be utilized to facilitate accurate pre- and post-test counseling in the settings of carrier screening and prenatal diagnosis for SMA.

  4. Hydrogen: the future energy carrier.

    Science.gov (United States)

    Züttel, Andreas; Remhof, Arndt; Borgschulte, Andreas; Friedrichs, Oliver

    2010-07-28

    Since the beginning of the twenty-first century the limitations of the fossil age with regard to the continuing growth of energy demand, the peaking mining rate of oil, the growing impact of CO2 emissions on the environment and the dependency of the economy in the industrialized world on the availability of fossil fuels became very obvious. A major change in the energy economy from fossil energy carriers to renewable energy fluxes is necessary. The main challenge is to efficiently convert renewable energy into electricity and the storage of electricity or the production of a synthetic fuel. Hydrogen is produced from water by electricity through an electrolyser. The storage of hydrogen in its molecular or atomic form is a materials challenge. Some hydrides are known to exhibit a hydrogen density comparable to oil; however, these hydrides require a sophisticated storage system. The system energy density is significantly smaller than the energy density of fossil fuels. An interesting alternative to the direct storage of hydrogen are synthetic hydrocarbons produced from hydrogen and CO2 extracted from the atmosphere. They are CO2 neutral and stored like fossil fuels. Conventional combustion engines and turbines can be used in order to convert the stored energy into work and heat.

  5. Methanol as an energy carrier

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, P.; Grube, T.; Hoehlein, B. (eds.)

    2006-07-01

    For the future, a strongly growing energy demand is expected in the transport sector worldwide. Economically efficient oil production will run through a maximum in the next decade. Higher fuel prices and an environmentally desirable reduction of emissions will increase the pressure for reducing fuel consumption and emissions in road traffic. These criteria show the urgent necessity of structural changes in the fuel market. Due to its advantages concerning industrial-scale production, storage and global availability, methanol has the short- to medium-term potential for gaining increased significance as a substitution product in the energy market. Methanol can be produced both from fossil energy sources and from biomass or waste materials through the process steps of synthesis gas generation with subsequent methanol synthesis. Methanol has the potential to be used in an environmentally friendly manner in gasoline/methanol mixtures for flexible fuel vehicles with internal combustion engines and in diesel engines with pure methanol. Furthermore, it can be used in fuel cell vehicles with on-board hydrogen production in direct methanol fuel cell drives, and in stationary systems for electricity and heat generation as well as for hydrogen production. Finally, in portable applications it serves as an energy carrier for electric power generation. In this book, the processes for the production and use of methanol are presented and evaluated, markets and future options are discussed and issues of safety and environmental impacts are addressed by a team of well-known authors. (orig.)

  6. Characteristics of THz carrier dynamics in GaN thin film and ZnO nanowires by temperature dependent terahertz time domain spectroscopy measurement

    Science.gov (United States)

    Balci, Soner; Baughman, William; Wilbert, David S.; Shen, Gang; Kung, Patrick; Kim, Seongsin Margaret

    2012-12-01

    We present a comprehensive study of the characteristics of carrier dynamics using temperature dependent terahertz time domain spectroscopy. By utilizing this technique in combination with numerical calculations, the complex refractive index, dielectric function, and conductivity of n-GaN, undoped ZnO NWs, and Al-doped ZnO NWs were obtained. The unique temperature dependent behaviors of major material parameters were studied at THz frequencies, including plasma frequency, relaxation time, carrier concentration and mobility. Frequency and temperature dependent carrier dynamics were subsequently analyzed in these materials through the use of the Drude and the Drude-Smith models.

  7. Carrier-carrier relaxation kinetics in quantum well semiconductor structures with nonparabolic energy bands

    DEFF Research Database (Denmark)

    Dery, H.; Tromborg, Bjarne; Eisenstein, G.

    2003-01-01

    We describe carrier-carrier scattering dynamics in an inverted quantum well structure including the nonparabolic nature of the valance band. A solution of the semiconductor Bloch equations yields strong evidence to a large change in the temporal evolution of the carrier distributions compared...... to the case of parabolic bands. The nonparabolic bands and the consequent change in the density of states reduce considerably the degree of gain saturation while decreasing the time constant governing the relaxation. This results in a measurable reduction of the role played by carrier-carrier scattering...

  8. Graphene for radio frequency electronics

    Directory of Open Access Journals (Sweden)

    Lei Liao

    2012-07-01

    Full Text Available Graphene is emerging as an attractive electronic material for future electronics. With the highest carrier mobility, high saturation velocity, high critical current densities, and single atomic thickness, graphene has great potential for ultra-high speed transistors, with the highest projected cut-off frequency exceeding 1 THz. However, the fabrication of high speed graphene transistors is of significant challenge, since conventional electronic fabrication processes often introduce undesirable defects into graphene lattices. Significant efforts have made to mitigate these challenges. Here we review the opportunities, challenges, as well as the recent advances in the development of high speed graphene transistors and circuits.

  9. A novel frequency synchronization scheme for OFDM systems

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-fang; LI Bing-bing

    2008-01-01

    A novel frequency synchronization scheme for orthogonal frequency division multiplexing(OFDM) systems is proposed,including a novel frequency offset estimation algorithm and a novel frequency offset compensation algorithm.The frequency offset estimation includes both the fractional frequency offset(FFO)estimation and the integral frequency offset(IFO)estimation.Firstly,the FFO WaSsobtained by the conventional ML algorithm in time domain.After the FFO was compensated in time domain,the IFO Was obtained by the proposed algorithm based on the energy of virtual carriers.This algorithm needs only simple calculations and has a large frequency offset estimation range.Furthermore,it is insensitive to symbol synchronization errors and channel changing.Finally,the IFO Was compensated based on the carrier-positions offset,which Can be completed through carrier-positions cyclic shifts in frequency domain.This proposed frequency synchronization scheme can decrease the system redundancy without any need of assistant data,and can be applied to the fast synchronization with the only need of one OFDM symbol.The analyses and simulations show the improved performance of the proposed frequency synchronization scheme.

  10. Continuous GPS Carrier-Phase Time Transfer

    Science.gov (United States)

    Yao, Jian

    Time transfer (TT) is the process of transmitting a timing signal from one place to another place. It has applications to the formation and realization of Coordinated Universal Time (UTC), telecommunications, electrical power grids, and even stock exchanges. TT is the actual bottleneck of the UTC formation and realization since the technology of atomic clocks is almost always ahead of that of TT. GPS carrier-phase time transfer (GPSCPTT), as a mainstream TT technique accepted by most national timing laboratories, has suffered from the day-boundary-discontinuity (day-BD) problem for many years. This makes us difficult to observe a remote Cesium fountain clock behavior even after a few days. We find that day-BD comes from the GPS code noise. The day-BD can be lowered by ˜40% if more satellite-clock information is provided and if a few GPS receivers at the same station are averaged. To completely eliminate day-BD, the RINEX-Shift (RS) and revised RS (RRS) algorithms have been designed. The RS/RRS result matches the two-way satellite time/frequency transfer (TWSTFT) result much better than the conventional GPSCPTT result. With the RS/RRS algorithm, we are able to observe a remote Cesium fountain after half a day. We also study the BD due to GPS data anomalies (anomaly-BD). A simple curve-fitting strategy can eliminate the anomaly-BD. Thus, we achieve continuous GPSCPTT after eliminating both day-BD and anomaly-BD.

  11. 77 FR 46555 - Motor Carrier Safety Advisory Committee: Public Meeting

    Science.gov (United States)

    2012-08-03

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee: Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of meeting of Motor Carrier... major motor carrier safety provisions of the recently enacted Moving Ahead for Progress in the...

  12. Frequency of fragile X chromosome in normal females.

    Science.gov (United States)

    Abuelo, D; Castree, K; Pueschel, S; Padre-Mendoza, T; Zolnierz, K

    1985-08-01

    Because of the ambiguities in diagnosing carriers of the fragile X syndrome, we studied thirty-six normal females to determine whether the fragile site at Xq27 can be seen in noncarrier females and at what frequency. A fragile site at Xq27 was identified in one out of thirty-six females, occurring at a frequency of 0.5% in her peripheral lymphocytes. We conclude that the fragile Xq27 site occurs only rarely in noncarrier females and that each laboratory should determine its own baseline frequencies of fragile X in order to most accurately distinguish between normal and carrier women.

  13. Differential Analysis of the Nasal Microbiome of Pig Carriers or Non-Carriers of Staphylococcus aureus

    DEFF Research Database (Denmark)

    Espinosa-Gongora, Carmen; Larsen, Niels; Schonning, Kristian;

    2016-01-01

    Staphylococcus aureus is presently regarded as an emerging zoonotic agent due to the spread of specific methicillin-resistant S. aureus (MRSA) clones in pig farms. Studying the microbiota can be useful for the identification of bacteria that antagonize such opportunistic veterinary and zoonotic...... pathogen in animal carriers. The aim of this study was to determine whether the nasal microbiome of pig S. aureus carriers differs from that of non-carriers. The V3-V5 region of the 16S rRNA gene was sequenced from nasal swabs of 44 S. aureus carriers and 56 non-carriers using the 454 GS FLX titanium...... system. Carriers and non-carriers were selected on the basis of quantitative longitudinal data on S. aureus carriage in 600 pigs sampled at 20 Danish herds included in two previous studies in Denmark. Raw sequences were analysed with the BION meta package and the resulting abundance matrix was analysed...

  14. Differential Analysis of the Nasal Microbiome of Pig Carriers or Non-Carriers of Staphylococcus aureus

    DEFF Research Database (Denmark)

    Espinosa-Gongora, Carmen; Larsen, Niels; Schonning, Kristian

    2016-01-01

    Staphylococcus aureus is presently regarded as an emerging zoonotic agent due to the spread of specific methicillin-resistant S. aureus (MRSA) clones in pig farms. Studying the microbiota can be useful for the identification of bacteria that antagonize such opportunistic veterinary and zoonotic...... pathogen in animal carriers. The aim of this study was to determine whether the nasal microbiome of pig S. aureus carriers differs from that of non-carriers. The V3-V5 region of the 16S rRNA gene was sequenced from nasal swabs of 44 S. aureus carriers and 56 non-carriers using the 454 GS FLX titanium...... system. Carriers and non-carriers were selected on the basis of quantitative longitudinal data on S. aureus carriage in 600 pigs sampled at 20 Danish herds included in two previous studies in Denmark. Raw sequences were analysed with the BION meta package and the resulting abundance matrix was analysed...

  15. Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

    Institute of Scientific and Technical Information of China (English)

    王立乔; 李建林; 张仲超

    2004-01-01

    A novel current-source active power filter(APF)based on multi-modular converter with carrier phase-shifted SPWM(CPS-SPWM)technique is proposed.With this technique,the effect of equivalent high switching frequency converter is obtained with low switching frequency converter.It is very promising in current-source APF that adopt superconducting magnetic energy storage component.

  16. Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit

    OpenAIRE

    Bin You; Bo Yang; Xuan Wen; Liangyu Qu

    2013-01-01

    A new ultrahigh frequency radio frequency identification (UHF RFID) reader’s front-end circuit which is based on zero-IF, single antenna structure and composed of discrete components has been designed. The proposed design brings a significant improvement of the reading performance by adopting a carrier leakage suppression (CLS) circuit instead of a circulator which is utilized by most of the conventional RF front-end circuit. Experimental results show that the proposed design improves both th...

  17. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber

    OpenAIRE

    R. Q. Shaddad; Mohammad, A. B.; S. A. Al-Gailani; Al-Hetar, A. M.

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the n...

  18. DSPI system based on spatial carrier phase shifting technique

    Science.gov (United States)

    Wang, Yonghong; Li, Junrui; Sun, Jianfei; Yang, Lianxiang

    2013-10-01

    Digital Speckle Pattern Interferometry (DSPI) is an optical method for measuring small displacement and deformation. It allows whole field, non-contacting measurement of micro deformation. Traditional Temporal phase shifting has been used for quantitative analyses in DSPI. The technique requires the recording of at least three phase-shifted interferograms, which must be taken sequentially. This can lead to disturbances by thermal and mechanical fluctuations during the required recording time. In addition, fast object deformations cannot be detected. In this paper a DSPI system using Spatial Carrier Phase Shifting (SCPS) technique is introduced, which is useful for extracting quantitative displacement data from the system with only two interferograms. The sensitive direction of this system refers to the illumination direction and observation direction. The frequencies of the spatial carrier relates to the angle between reference light and observation direction. Fourier transform is adopted in the digital evaluation to filter out the frequencies links to the deformation of testing object. The phase is obtained from the complex matrix formed by inverse Fourier transform, and the phase difference and deformation are calculated subsequently. Comparing with conventional temporal phase shifting, the technique can achieve measuring the vibration and transient deformation of testing object. Experiment set-ups and results are presented in this paper, and the experiment results have shown the effectiveness and advantages of the SCPS technique.

  19. Frequency Standards and Metrology

    Science.gov (United States)

    Maleki, Lute

    2009-04-01

    : its construction and performance (Invited) / T. Li ... [et al.].Compensated multi-pole mercury trapped ion frequency standard and stability evaluation of systematic effects (Invited) / E. A. Burt ... [et al.]. Research of frequency standards in SIOM - atomic frequency standards based on coherent storage (Invited) / B. Yan ... [et al.]. The PTB fountain clock ensemble preliminary characterization of the new fountain CSF2 / N. Nemitz ... [et al.]. The pulsed optically pumped clock: microwave and optical detection / S. Micalizio ... [et al.]. Research on characteristics of pulsed optically pumped rubidium frequency standard / J. Deng ... [et al.]. Status of the continuous cold fountain clocks at METAS-LTF / A. Joyet ... [et al.]. Experiments with a new [symbol]Hg+ ion clock / E. A. Burt ... [et al.]. Optimising a high-stability CW laser-pumped rubidium gas-cell frequency standard / C. Affolderbach ... [et al.]. Raman-Ramsey Cs cell atomic clock / R. Boudot ... [et al.] -- pt. VIII. Microwave resonators & oscillators. Solutions and ultimate limits in temperature compensation of metallic cylindrical microwave resonators (Invited) / A. De Marchi. Cryogenic sapphire oscillators (Invited) / J. G. Hartnett, E. N. Ivanov and M. E. Tobar. Ultra-stable optical cavity: design and experiments / J. Millo ... [et al.]. New results for whispering gallery mode cryogenic sapphire maser oscillators / K. Benmessai ... [et al.] -- pt. IX. Advanced techniques. Fundamental noise-limited optical phase locking at Femtowatt light levels (Invited) / J. Dick ... [et al.]. Microwave and optical frequency transfer via optical fibre / G. Marra ... [et al.]. Ultra-stable laser source for the [symbol]Sr+ single-ion optical frequency standard at NRC / P. Dubé, A. A. Madej and J. E. Bernard. Clock laser system for a strontium lattice clock / T. Legero ... [et al.]. Measurement noise floor for a long-distance optical carrier transmission via fiber / G. Grosche ... [et al.]. Optical frequency transfer

  20. Carrier scattering in metals and semiconductors

    CERN Document Server

    Gantmakher, VF

    1987-01-01

    The transport properties of solids, as well as the many optical phenomena in them are determined by the scattering of current carriers. ``Carrier Scattering in Metals and Semiconductors'' elucidates the state of the art in the research on the scattering mechanisms for current carriers in metals and semiconductors and describes experiments in which these mechanisms are most dramatically manifested.The selection and organization of the material is in a form to prepare the reader to reason independently and to deal just as independently with available theoretical results and experimental

  1. High capacity carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao

    2009-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and T-MPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  2. Towards 100 gigabit carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao

    2010-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and TMPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  3. What It Means to be a Carrier

    Science.gov (United States)

    ... Life Planning Daily Living Strategies Genetic Counselor Research Biomarker Research Program News, Reports and Commentaries Previously Funded ... with the premutation are at increased risk for depression. It is therefore recommended that any premutation carrier ...

  4. What It Means to be a Carrier

    Science.gov (United States)

    ... in premutation carriers were an increased rate of twin births and of premature ovarian failure (POI). .. We ... also performed to confirm the “preliminary” result). Preimplantation Genetic Diagnosis (PGD) PGD is a process whereby a ...

  5. Physician Fee Schedule Carrier Specific Files

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Centers for Medicare and Medicaid Services (CMS) has condensed all 56 Physician Fee Schedule (PFS) carrier specific pricing files into one zip file. It is...

  6. Towards 100 gigabit carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao;

    2010-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and TMPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  7. High capacity carrier ethernet transport networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Zhang, Jiang; Yu, Hao;

    2009-01-01

    Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and T-MPLS, it is now possible to use Ethernet as a transport...... technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced...... OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error...

  8. Synthetic Lipoproteins as Carriers for Drug Delivery.

    Science.gov (United States)

    Huang, Gangliang; Liu, Yang; Huang, Hualiang

    2016-01-01

    Synthetic lipoprotein is an effective carrier of targeted delivery for drugs. It has the very small size, good biocompatibility, suitable half-life, and specific lipoprotein receptorbinding capacity. Compared with the traditional natural lipoprotein, synthetic lipoprotein not only retains the original biological characteristics and functions, but also exhibits the excellent characteristics in drug delivery. Herein, the advantages, development, applications, and prospect of synthetic lipoproteins as drug carriers were summarized.

  9. Evaluating multicast resilience in carrier ethernet

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang;

    2010-01-01

    This paper gives an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we show how multicast traffic, which is essential for IPTV can be protected. We detail the ackground for resilience mechanisms and their control and e present Carrier Ethernet...... resilience methods for linear nd ring networks. By simulation we show that the vailability of a multicast connection can be significantly increased by applying protection methods....

  10. Evaluating multicast resilience in carrier ethernet

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2010-01-01

    This paper gives an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we show how multicast traffic, which is essential for IPTV can be protected. We detail the ackground for resilience mechanisms and their control and e present Carrier Ethernet...... resilience methods for linear nd ring networks. By simulation we show that the vailability of a multicast connection can be significantly increased by applying protection methods....

  11. Minority carrier lifetime in indium phosphide

    Science.gov (United States)

    Jenkins, Phillip; Landis, Geoffrey A.; Weinberg, Irving; Kneisel, Keith

    1991-01-01

    Transient photoluminescence is used to measure the minority carrier lifetime on n-type and p-type InP wafers. The measurements show that unprocessed InP wafers have very high minority carrier lifetimes. Lifetimes of 200 ns and 700 ns were observed for lightly-doped p- and n-type material respectively. Lifetimes over 5 ns were found in heavily doped n-type material.

  12. Taenia solium cysticercosis hotspots surrounding tapeworm carriers: clustering on human seroprevalence but not on seizures.

    Directory of Open Access Journals (Sweden)

    Andres G Lescano

    Full Text Available Neurocysticercosis accounts for 30%-50% of all late-onset epilepsy in endemic countries. We assessed the clustering patterns of Taenia solium human cysticercosis seropositivity and seizures around tapeworm carriers in seven rural communities in Peru.The presence of T. solium-specific antibodies was defined as one or more positive bands in the enzyme-linked immunoelectrotransfer blot (EITB. Neurocysticercosis-related seizures cases were diagnosed clinically and had positive neuroimaging or EITB.Eleven tapeworm carriers were identified by stool microscopy. The seroprevalence of human cysticercosis was 24% (196/803. Seroprevalence was 21% >50 m from a carrier and increased to 32% at 1-50 m (p = 0.047, and from that distance seroprevalence had another significant increase to 64% at the homes of carriers (p = 0.004. Seizure prevalence was 3.0% (25/837 but there were no differences between any pair of distance ranges (p = 0.629, Wald test 2 degrees of freedom.We observed a significant human cysticercosis seroprevalence gradient surrounding current tapeworm carriers, although cysticercosis-related seizures did not cluster around carriers. Due to differences in the timing of the two outcomes, seroprevalence may reflect recent T. solium exposure more accurately than seizure frequency.

  13. Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot Carriers in Graphene

    Science.gov (United States)

    Sierra, Juan F.; Neumann, Ingmar; Costache, Marius V.; Valenzuela, Sergio O.

    2015-06-01

    We investigate hot carrier propagation across graphene using an electrical nonlocal injection/detection method. The device consists of a monolayer graphene flake contacted by multiple metal leads. Using two remote leads for electrical heating, we generate a carrier temperature gradient that results in a measurable thermoelectric voltage VNL across the remaining (detector) leads. Due to the nonlocal character of the measurement, VNL is exclusively due to the Seebeck effect. Remarkably, a departure from the ordinary relationship between Joule power P and VNL, VNL ~ P, becomes readily apparent at low temperatures, representing a fingerprint of hot-carrier dominated thermoelectricity. By studying VNL as a function of bias, we directly determine the carrier temperature and the characteristic cooling length for hot-carrier propagation, which are key parameters for a variety of new applications that rely on hot-carrier transport.

  14. Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot Carriers in Graphene.

    Science.gov (United States)

    Sierra, Juan F; Neumann, Ingmar; Costache, Marius V; Valenzuela, Sergio O

    2015-06-10

    We investigate hot carrier propagation across graphene using an electrical nonlocal injection/detection method. The device consists of a monolayer graphene flake contacted by multiple metal leads. Using two remote leads for electrical heating, we generate a carrier temperature gradient that results in a measurable thermoelectric voltage V(NL) across the remaining (detector) leads. Due to the nonlocal character of the measurement, V(NL) is exclusively due to the Seebeck effect. Remarkably, a departure from the ordinary relationship between Joule power P and V(NL), V(NL) ∼ P, becomes readily apparent at low temperatures, representing a fingerprint of hot-carrier dominated thermoelectricity. By studying V(NL) as a function of bias, we directly determine the carrier temperature and the characteristic cooling length for hot-carrier propagation, which are key parameters for a variety of new applications that rely on hot-carrier transport.

  15. Radio Science Measurements with Suppressed Carrier

    Science.gov (United States)

    Asmar, Sami; Divsalar, Dariush; Oudrhiri, Kamal

    2013-01-01

    Radio Science started when it became apparent with early Solar missions that occultations by planetary atmospheres would affect the quality of radio communications. Since then the atmospheric properties and other aspects of planetary science, solar science, and fundamental physics were studied by scientists. Radio Science data was always extracted from a received pure residual carrier (without data modulation). For some missions, it is very desirable to obtain Radio Science data from a suppressed carrier modulation. In this paper we propose a method to extract Radio Science data when a coded suppressed carrier modulation is used in deep space communications. Type of modulation can be BPSK, QPSK, OQPSK, MPSK or even GMSK. However we concentrate mostly on BPSK modulation. The proposed method for suppressed carrier simply tries to wipe out data that acts as an interference for Radio Science measurements. In order to measure the estimation errors in amplitude and phase of the Radio Science data we use Cramer-Rao bound (CRB). The CRB for the suppressed carrier modulation with non-ideal data wiping is then compared with residual carrier modulation under the same noise condition. The method of derivation of CRB for non-ideal data wiping is an innovative method that presented here. Some numerical results are provided for coded system.

  16. Influence of Inter Carrier Interference on Link Adaptation Algorithms in OFDM Systems

    DEFF Research Database (Denmark)

    Das, Suvra S.; Rahman, Muhammad Imadur; Wang, Yuanye

    2007-01-01

    The performance of Link Adaptation (LA) under the influence of inter carrier interference (ICI), which is cause by carrier frequency offset (CFO) and Doppler frequency spread due to mobility, in orthogonal frequency division multiplexing (OFDM) based wireless systems is analyzed in this work. LA...... maximizes throughput while maintaining a target bit error rate (BER)or Block Error Rate (BLER) at the receiver using the signal to noise ratio (SNR) fed back from the receiver to the transmitter. Since ICI power is proportional to the signal strength, the implications of such an impairment on LA OFDM...... can over the problem. It is also noted that ICI severely reduces the spectral efficiency of OFDM systems even when LA is used....

  17. Current fluctuation of electron and hole carriers in multilayer WSe{sub 2} field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Seung-Pil; Shin, Jong Mok; Jang, Ho-Kyun; Jin, Jun Eon; Kim, Gyu-Tae, E-mail: gtkim@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 02481 (Korea, Republic of); Kim, Yong Jin; Kim, Young Keun [Department of Materials Science and Engineering, Korea University, Seoul 02481 (Korea, Republic of); Shin, Minju [School of Electrical Engineering, Korea University, Seoul 02481 (Korea, Republic of); IMEP-LAHC, Grenoble INP-MINATEC, 3 Parvis Louis Neel, 38016 Grenoble (France)

    2015-12-14

    Two-dimensional materials have outstanding scalability due to their structural and electrical properties for the logic devices. Here, we report the current fluctuation in multilayer WSe{sub 2} field effect transistors (FETs). In order to demonstrate the impact on carrier types, n-type and p-type WSe{sub 2} FETs are fabricated with different work function metals. Each device has similar electrical characteristics except for the threshold voltage. In the low frequency noise analysis, drain current power spectral density (S{sub I}) is inversely proportional to frequency, indicating typical 1/f noise behaviors. The curves of the normalized drain current power spectral density (NS{sub I}) as a function of drain current at the 10 Hz of frequency indicate that our devices follow the carrier number fluctuation with correlated mobility fluctuation model. This means that current fluctuation depends on the trapping-detrapping motion of the charge carriers near the channel interface. No significant difference is observed in the current fluctuation according to the charge carrier type, electrons and holes that occurred in the junction and channel region.

  18. Actively stabilized wavelength-insensitive carrier elimination from an electro-optically modulated laser beam

    CERN Document Server

    Cooper, Nathan; Dunning, Alexander; Freegarde, Tim

    2012-01-01

    We demonstrate a simple and robust technique for removal of the carrier wave from a phase-modulated laser beam, using a non-interferometric method that is insensitive to the modulation frequency and instead exploits the polarization-dependence of electro-optic modulation. An actively stabilized system using feedback via a liquid crystal cell yields long-term carrier suppression in excess of 28 dB at the expense of a 6.5 dB reduction in sideband power.

  19. Serum Levels of MicroRNA-206 and Novel Mini-STR Assays for Carrier Detection in Duchenne Muscular Dystrophy

    Science.gov (United States)

    Anaya-Segura, Mónica Alejandra; Rangel-Villalobos, Héctor; Martínez-Cortés, Gabriela; Gómez-Díaz, Benjamín; Coral-Vázquez, Ramón Mauricio; Zamora-González, Edgar Oswaldo; García, Silvia; López-Hernández, Luz Berenice

    2016-01-01

    Duchenne Muscular Dystrophy (DMD) is an X-linked neuromuscular disorder in which the detection of female carriers is of the utmost importance for genetic counseling. Haplotyping with polymorphic markers and quantitation of creatine kinase levels (CK) allow tracking of the at-risk haplotype and evidence muscle damage, respectively. Such approaches are useful for carrier detection in cases of unknown mutations. The lack of informative markers and the inaccuracy of CK affect carrier detection. Therefore, herein we designed novel mini-STR (Short Tandem Repeats) assays to amplify 10 loci within the DMD gene and estimated allele frequencies and the polymorphism information content among other parameters in 337 unrelated individuals from three Mexican populations. In addition, we tested the utility of the assays for carrier detection in three families. Moreover, given that serum levels of miR-206 discern between DMD patients and controls with a high area under the curve (AUC), the potential applicability for carrier detection was assessed. The serum levels of miR-206 of non-carriers (n = 24) and carriers (n = 23) were compared by relative quantitation using real-time PCR (p < 0.05), which resulted in an AUC = 0.80 in the Receiver Operating Characteristic curve analysis. In conclusion, miR-206 has potential as a “liquid biopsy” for carrier detection and genetic counseling in DMD. PMID:27529242

  20. Serum Levels of MicroRNA-206 and Novel Mini-STR Assays for Carrier Detection in Duchenne Muscular Dystrophy

    Directory of Open Access Journals (Sweden)

    Mónica Alejandra Anaya-Segura

    2016-08-01

    Full Text Available Duchenne Muscular Dystrophy (DMD is an X-linked neuromuscular disorder in which the detection of female carriers is of the utmost importance for genetic counseling. Haplotyping with polymorphic markers and quantitation of creatine kinase levels (CK allow tracking of the at-risk haplotype and evidence muscle damage, respectively. Such approaches are useful for carrier detection in cases of unknown mutations. The lack of informative markers and the inaccuracy of CK affect carrier detection. Therefore, herein we designed novel mini-STR (Short Tandem Repeats assays to amplify 10 loci within the DMD gene and estimated allele frequencies and the polymorphism information content among other parameters in 337 unrelated individuals from three Mexican populations. In addition, we tested the utility of the assays for carrier detection in three families. Moreover, given that serum levels of miR-206 discern between DMD patients and controls with a high area under the curve (AUC, the potential applicability for carrier detection was assessed. The serum levels of miR-206 of non-carriers (n = 24 and carriers (n = 23 were compared by relative quantitation using real-time PCR (p < 0.05, which resulted in an AUC = 0.80 in the Receiver Operating Characteristic curve analysis. In conclusion, miR-206 has potential as a “liquid biopsy” for carrier detection and genetic counseling in DMD.

  1. Accurate and Simple Time Synchronization and Frequency Offset Correction in OFDM System

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ming; JIANG Wei-yu; LIU Yuan-an

    2004-01-01

    We present a new synchronization scheme for Orthogonal Frequency-Division Multiplexing (OFDM) systems. In this scheme, time synchronization and carrier frequency offset correction can be performed in one identical training symbol. Time synchronization algorithm is robust and simple operated, and its performance is independent of the carrier frequency offset. We derive the theoretical variance error for our time synchronization algorithm in AWGN channel. We also derive the performance lower bound of our frequency offset correction algorithm. The frequency offset correction algorithm is high accuracy and its performance will degrade very little under multipath fading environment.

  2. Parametric frequency dividers in satellite communications

    OpenAIRE

    Kosmopoulos, S. A.; Lo Forti, R.; Saggese, E.

    1990-01-01

    The performance of two different parametric frequency dividers, using GaAs varactor diodes in a balanced circuit configuration implemented by planar (microstrip) or quasi-planar (finline, coupled finline ) elements respectively, is presented. The almost phase noise free operation of these devices allows the construction of efficient miniature synthesizers or carrier recovering schemes, incorporated on the space segment of Ku- or Ka-band satellite communications systems.

  3. Performance of Uplink Carrier Aggregation in LTE-Advanced Systems

    DEFF Research Database (Denmark)

    Wang, Hua; Rosa, Claudio; Pedersen, Klaus

    2010-01-01

    Carrier aggregation (CA) has been proposed to aggregate two or more component carriers (CCs) to support a much wider transmission bandwidth for LTE-Advanced systems. With carrier aggregation, it is possible to schedule a user equipment (UE) on multiple component carriers simultaneously. In this p...

  4. 76 FR 32390 - Motor Carrier Safety Advisory Committee Public Meeting

    Science.gov (United States)

    2011-06-06

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Public Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Motor Carrier Safety Advisory... MCSAC will complete action on Task 11-01, regarding Patterns of Safety Violations by Motor...

  5. 47 CFR 64.1140 - Carrier liability for slamming.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Carrier liability for slamming. 64.1140 Section 64.1140 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES... Providers § 64.1140 Carrier liability for slamming. (a) Carrier Liability for Charges. Any...

  6. A novel Modulation Topology for Power Converters utilizing Multiple Carrier Signals

    DEFF Research Database (Denmark)

    Knott, Arnold; Pfaffinger, Gerhard; Andersen, Michael Andreas E.

    2008-01-01

    Power converters are known to generate spectral components in the range of interest of electromagnetic compatibility measurements. Common approaches to manipulate some selected components in these frequency ranges are shown here. These approaches add components to the input signal of the modulator...... to derive a slightly varied spectrum. To achieve a rectangular output signal, those modulators use a triangular or saw tooth carrier signal. A novel family of modulators is shown here, using more than one carrier signal to obtain a completely changed spectrum while maintaining the rectangular shaped...... waveform at the output. The multiple carriers are fed into multiple comparators and their outputs are intelligently combined by logic gates to get a single signal to drive one power stage of any type of converter. This commutation distinguishes between the four members of the novel family: the first one...

  7. Performance Evaluation of the New Compound-Carrier-Modulated Signal for Future Navigation Signals

    Directory of Open Access Journals (Sweden)

    Ruidan Luo

    2016-01-01

    Full Text Available Navigation Signal based on Compound Carrier (NSCC, is proposed as the potential future global navigation satellite system (GNSS signal modulation scheme. NSCC, a kind of multi-carrier (MC signal, is generated by superposition and multi-parameter adjustment of sub-carriers. Therefore, a judious choice of parameter configation is needed. The main objective of this paper is to investigate the performance of the NSCC which is influenced by these parameters and to demonstrate its structure characteristics and superiority, employing a comprehensive evaluation system. The results show that the proposed NSCC signal processes full spectral efficiency and limited out of band (OOB emissions, satisfying the demands of crowed frequency resources. It also presents better performance in terms of spectral separation coefficients (SSCs, tracking accuracy, multipath mitigation capability and anti-jamming reduction compared with the legacy navigation signals. NSCC modulation represents a serious candidate for navigation satellite augmentation systems, especially for signals applied in challenging environments.

  8. Method to reinforce polylactic acid with cellulose nanofibers via a polyhydroxybutyrate carrier system.

    Science.gov (United States)

    Kiziltas, Alper; Nazari, Behzad; Erbas Kiziltas, Esra; Gardner, Douglas J; Han, Yousoo; Rushing, Todd S

    2016-04-20

    The elastic moduli of PLA reinforced with 5 and 10wt.% CNF with the carrier, at a frequency (ω) of 0.07, were 67% and 415% higher, respectively, than that of neat PLA. The shear viscosity at a shear rate of 0.01 (η0.01) for PLA+10wt.% CNF was 32% higher than that of the neat PLA matrix. The η0.01 of PLA reinforced with 5wt.% CNF and the PHB carrier was similar to neat PLA. The tensile and flexural moduli of elasticity of the nanocomposites continuously increased with increased CNF loading. The results of the mechanical property measurements are in accordance with the rheological data. The CNF appeared to be better dispersed (less-aggregated nanofibers) in the PLA reinforced with 5wt.% CNF and the PHB carrier. Possible applications for the composites studied in this research are packaging materials, construction materials, and auto parts for interior applications.

  9. Coherent Digital Demodulation of a Residual Carrier Signal Using IF Sampling

    Science.gov (United States)

    Sfeir, R.; Aguirre, S.; Hurd, W. J.

    1984-01-01

    An analysis is presented of a digital technique for the coherent demodulation of a residual carrier signal with a biphase modulated square wave subcarrier. The processing technique employs the concept of intermediate frequencies IF sampling. An optimum Costas loop is used for subcarrier demodulation and data-aided carrier tracking, i.e., combined Costas and residual carrier tracking. It is shown that the loops perform essentially the same as the corresponding analog loops in terms of signal-to-noise ratio and loop bandwidth. The sampling does not introduce biases or other significant effects on the loops, provided that the loop bandwidth is very small compared to the symbol rate, and that the number of samples per symbol is large compared to inverse loop bandwidth.

  10. Development of radioisotope labeled polymeric carriers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jin; Jeong, Jea Min; Hwang, Hyun Jeong [Ewha Womans University, Seoul (Korea)

    2000-04-01

    This research was performed with the aim of developing polymeric radioisotope or drug carriers for obtaining efficient diagnostic therapeutic efficacy. As polymers, polyethylene oxides, polylactides, polycaprolactone were chosen to prepare the devices including micelle system, microemulsion, nanospheres. In addition, anticancer drug loaded polylactide microparticulates were fabricated as a regional chemotherapeutics for the treatment of cancer. Technetium or radioactive iodine was labeled to the polymeric carriers via ligands such as DTPA and HPP, respectively. Labeling efficiency was above 90% and stable enough up to 24 hours. Moreover, injected polymer carriers demonstrated higher blood maintenance and bone uptake than Tin colloid, a control. These results suggested that radioisotope carrying polymeric particulate are promising tools for diagnosing blood vessels or bones. Besides, anticancer drug loaded particulates demonstrated appropriate maintenance of therapeutic concentration and localization. Therefore it was proposed that this therapeutic system may be potential as a cancer therapy modality. 20 refs., 24 figs.,5 tabs. (Author)

  11. Carrier lifetimes in thin-film photovoltaics

    Science.gov (United States)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  12. Quinolones in the treatment of Salmonella carriers.

    Science.gov (United States)

    Rodríguez-Noriega, E; Andrade-Villanueva, J; Amaya-Tapia, G

    1989-01-01

    Infections caused by Salmonella typhi are commonly followed by a chronic carrier state despite positive clinical and initial bacteriologic responses. The use of primary antibiotics like chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole has several major drawbacks, including in some instances the failure to prevent the carrier state. The appearance worldwide of strains with multiple resistance to the most commonly used regimens has prompted the search for new forms of therapy. Among the agents studied have been third-generation cephalosporins and quinolones, which are active in vitro against bacterial enteropathogens like S. typhi. Resolution of chronic carriage of S. typhi and other salmonellae is difficult, and regimens commonly fail (including those that combine antibiotic administration with removal of the gallbladder). In addition to being active in vitro against Salmonella species, the newer quinolones adequately penetrate the intestinal lumen, liver, bile, and gallbladder. Initial experience with norfloxacin and ciprofloxacin in oral treatment of the chronic S. typhi carrier state in adults has been promising.

  13. Hot Carrier extraction with plasmonic broadband absorbers

    CERN Document Server

    Ng, Charlene; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gomez, Daniel E

    2016-01-01

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to $\\sim$ 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the S...

  14. Natural carriers in bioremediation: A review

    Directory of Open Access Journals (Sweden)

    Anna Dzionek

    2016-09-01

    Full Text Available Bioremediation of contaminated groundwater or soil is currently the cheapest and the least harmful method of removing xenobiotics from the environment. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes, reduces their costs, and also allows for the multiple use of biocatalysts. Among the developed methods of immobilization, adsorption on the surface is the most common method in bioremediation, due to the simplicity of the procedure and its non-toxicity. The choice of carrier is an essential element for successful bioremediation. It is also important to consider the type of process (in situ or ex situ, type of pollution, and properties of immobilized microorganisms. For these reasons, the article summarizes recent scientific reports about the use of natural carriers in bioremediation, including efficiency, the impact of the carrier on microorganisms and contamination, and the nature of the conducted research.

  15. [Therapy of hepatitis B virus carriers].

    Science.gov (United States)

    Bereza, N M; Petiĭ, S I

    1986-01-01

    Examination of 200 gastroenterological patients with a suspected chronic diffuse liver disease has demonstrated that only in 18.9% of the patients with chronic hepatitis, the disease was induced by the virus. Based on the experience gained with the treatment of 7 patients with chronic hepatitis B it is concluded that sanitation may be performed with levamisole. However, the data obtained in the course of the 5-year observation over sanitation of HBsAg carriers (25 subjects) do not provide any convincing evidence in favour of levamisole sanitation. The authors hold that at the blood transfusion stations the prophylaxis of serum hepatitis falls short of ideal. Selection of the donors according to CCIE does not give any guarantee against the viral hepatitis B carrier state. Like patients with viral hepatitis B, the HBsAg carriers badly need active prophylactic-and-treatment medical examination with the use of the antiviral agents.

  16. Effective Charge Carrier Utilization in Photocatalytic Conversions.

    Science.gov (United States)

    Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

    2016-05-17

    Continuous efforts have been devoted to searching for sustainable energy resources to alleviate the upcoming energy crises. Among various types of new energy resources, solar energy has been considered as one of the most promising choices, since it is clean, sustainable, and safe. Moreover, solar energy is the most abundant renewable energy, with a total power of 173 000 terawatts striking Earth continuously. Conversion of solar energy into chemical energy, which could potentially provide continuous and flexible energy supplies, has been investigated extensively. However, the conversion efficiency is still relatively low since complicated physical, electrical, and chemical processes are involved. Therefore, carefully designed photocatalysts with a wide absorption range of solar illumination, a high conductivity for charge carriers, a small number of recombination centers, and fast surface reaction kinetics are required to achieve a high activity. This Account describes our recent efforts to enhance the utilization of charge carriers for semiconductor photocatalysts toward efficient solar-to-chemical energy conversion. During photocatalytic reactions, photogenerated electrons and holes are involved in complex processes to convert solar energy into chemical energy. The initial step is the generation of charge carriers in semiconductor photocatalysts, which could be enhanced by extending the light absorption range. Integration of plasmonic materials and introduction of self-dopants have been proved to be effective methods to improve the light absorption ability of photocatalysts to produce larger amounts of photogenerated charge carriers. Subsequently, the photogenerated electrons and holes migrate to the surface. Therefore, acceleration of the transport process can result in enhanced solar energy conversion efficiency. Different strategies such as morphology control and conductivity improvement have been demonstrated to achieve this goal. Fine-tuning of the

  17. A new lubricant carrier for metal forming

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Bay, Niels; Tang, Peter Torben

    2009-01-01

    A lubricant carrier for metal forming processes is developed. Surfaces with pores of micrometer size for entrapping lubricant are generated by electrochemical deposition of an alloy, consisting of two immiscible metals, of which one metal subsequently is etched away leaving 5 mu m layers with a s......A lubricant carrier for metal forming processes is developed. Surfaces with pores of micrometer size for entrapping lubricant are generated by electrochemical deposition of an alloy, consisting of two immiscible metals, of which one metal subsequently is etched away leaving 5 mu m layers...

  18. Hot-carrier effects in MOS devices

    CERN Document Server

    Takeda, Eiji; Miura-Hamada, Akemi

    1995-01-01

    The exploding number of uses for ultrafast, ultrasmall integrated circuits has increased the importance of hot-carrier effects in manufacturing as well as for other technological applications. They are rapidly movingout of the research lab and into the real world.This book is derived from Dr. Takedas book in Japanese, Hot-Carrier Effects, (published in 1987 by Nikkei Business Publishers). However, the new book is much more than a translation. Takedas original work was a starting point for developing this much more complete and fundamental text on this increasingly important topic. The new work

  19. Biogenesis of the mitochondrial phosphate carrier

    OpenAIRE

    Zara, Vincenzo; Rassow, Joachim; Wachter, Elmar; Tropschug, Maximilian; Palmieri, Ferdinando; Neupert, Walter; Pfanner, Nikolaus

    1991-01-01

    The mitochondrial phosphate carrier (PiC) is a member of the family of inner-membrane carrier proteins which are generally synthesized without a cleavable presequence. Surprisingly, the cDNA sequences of bovine and rat PiC suggested the existence of an amino-terminal extension sequence in the precursor of PiC. By expressing PiC in vitro, we found that PiC is indeed synthesized as a larger precursor. This precursor was imported and proteolytically processed by mitochondria, whereby the correct...

  20. Hot carrier effects on jitter and phase noise in CMOS voltage-controlled oscillators

    Science.gov (United States)

    Zhang, Chi; Srivastava, Ashok

    2005-05-01

    The effects of hot carrier stress on CMOS voltage-controlled oscillators (VCO) are investigated. A model of the threshold voltage degradation in MOSFETs due to hot carrier stress has been used to model jitter and phase noise in voltage-controlled oscillators. The relation between the stress time which induces the hot carrier effects and the degradation of the VCO performance is presented. The VCO performance degradation takes into consideration decrease in operation frequency, increase in jitter and phase noise and decrease in tuning range. The experimental circuits have been designed in 0.5 μm n-well CMOS technology for operation at 3 V. It is shown that when the MOSFET threshold voltage, increases from 0.4 V to 0.9 V due to the hot carrier effect, for the single-ended ring oscillator, the oscillation frequency changes from 538 MHz to 360 MHz, and the phase noise changes from -104 dBc to -105 dBc at 1 MHz frequency offset with a power dissipation of 0.37 mW. For the current-starved VCO, the tuning range changes from 72 MHz - 287 MHz to 65.4 MHz - 201 MHz, and the phase noise changes from -109 dBc to -107 dBc at 1 MHz offset from the center frequency, 200 MHz; for the double-ended differential VCO, the tuning range changes from 32 MHz - 983 MHz to 26 MHz - 698 MHz, and phase noise changes from -86 dBc to -87 dBc at 1 MHz offset from the center frequency, 700 MHz.

  1. Frequency unlimited optical delay lines based on slow and fast light in SOAs

    DEFF Research Database (Denmark)

    Berger, Perrine; Bourderionnet, Jérôme; Pu, Minhao

    2011-01-01

    We experimentally demonstrate that up-converted coherent population oscillations (CPO) in SOA open the possibility to conceive integrated optical tunable delay lines beyond the carrier lifetime limit, up to THz frequencies....

  2. Line broadening caused by Coulomb carrier-carrier correlations and dynamics of carrier capture and emission in quantum dots

    DEFF Research Database (Denmark)

    Uskov, Alexander V; Magnúsdóttir, Ingibjörg; Tromborg, Bjarne;

    2001-01-01

    Mechanisms of pure dephasing in quantum dots due to Coulomb correlations and the dynamics of carrier capture and emission are suggested, and a phenomenological model for the dephasing is developed. It is shown that, if the rates of these capture and emission processes are sufficiently high...

  3. Two novel automatic frequency tracking loops

    Science.gov (United States)

    Aguirre, Sergio; Hinedi, Sami

    1989-01-01

    Two automatic-frequency-control (AFC) loops are introduced and analyzed in detail. The algorithms are generalizations of the well known cross-product AFC loop with improved performance. The first estimator uses running overlapping discrete Fourier transforms to create a discriminator curve proportional to the frequency estimation error, whereas the second one preprocesses the received data and then uses an extended Kalman filter to estimate the input frequency. The algorithms are tested by computer simulations in a highly dynamic environment at low carrier/noise ratio (CNR). The algorithms are suboptimum tracking schemes with a larger frequency-error variance compared to an optimum strategy, but they offer simplicity of mechanization and a CNR with a very low operating threshold.

  4. Frequency unlimited optical delay lines based on slow and fast light in SOAs

    DEFF Research Database (Denmark)

    Berger, Perrine; Bourderionnet, Jérôme; Pu, Minhao

    2011-01-01

    We experimentally demonstrate that up-converted coherent population oscillations (CPO) in SOA open the possibility to conceive integrated optical tunable delay lines beyond the carrier lifetime limit, up to THz frequencies.......We experimentally demonstrate that up-converted coherent population oscillations (CPO) in SOA open the possibility to conceive integrated optical tunable delay lines beyond the carrier lifetime limit, up to THz frequencies....

  5. Design and Performance Evaluation of a Dual Antenna Joint Carrier Tracking Loop

    Directory of Open Access Journals (Sweden)

    Wenfei Guo

    2015-10-01

    Full Text Available In order to track the carrier phases of Global Navigation Satellite Systems (GNSS signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capture signals in degraded environments. In this architecture, a Phase Lock Loop (PLL is adopted as a master loop to track the carrier phase of the open-sky signals. The Doppler frequency estimated by this master loop is utilized to assist weak carrier tracking in the slave loop. As both antennas experience similar signal dynamics due to satellite motion and clock frequency variations, a much narrower loop bandwidth and possibly a longer coherent integration can be adopted to track the weak signals in slave channels, by utilizing the Doppler aid from master channels. PLL tracking performance is affected by the satellite/user dynamics, clock instability, and thermal noise. In this paper, their impacts on the proposed phase tracking loop are analyzed and verified by both simulation and field data. Theoretical analysis and experimental results show that the proposed loop structure can track degraded signals (i.e., 18 dB-Hz with a very narrow loop bandwidth (i.e., 0.5 Hz and a TCXO clock.

  6. Design and Performance Evaluation of a Dual Antenna Joint Carrier Tracking Loop.

    Science.gov (United States)

    Guo, Wenfei; Lin, Tao; Niu, Xiaoji; Shi, Chuang; Zhang, Hongping

    2015-10-01

    In order to track the carrier phases of Global Navigation Satellite Systems (GNSS) signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capture signals in degraded environments. In this architecture, a Phase Lock Loop (PLL) is adopted as a master loop to track the carrier phase of the open-sky signals. The Doppler frequency estimated by this master loop is utilized to assist weak carrier tracking in the slave loop. As both antennas experience similar signal dynamics due to satellite motion and clock frequency variations, a much narrower loop bandwidth and possibly a longer coherent integration can be adopted to track the weak signals in slave channels, by utilizing the Doppler aid from master channels. PLL tracking performance is affected by the satellite/user dynamics, clock instability, and thermal noise. In this paper, their impacts on the proposed phase tracking loop are analyzed and verified by both simulation and field data. Theoretical analysis and experimental results show that the proposed loop structure can track degraded signals (i.e., 18 dB-Hz) with a very narrow loop bandwidth (i.e., 0.5 Hz) and a TCXO clock.

  7. Carrier Aggregation for LTE-Advanced

    DEFF Research Database (Denmark)

    Pedersen, Klaus Ingemann; Frederiksen, Frank; Rosa, Claudio

    2011-01-01

    Carrier aggregation (CA) is one of the key features for LTE-Advanced. By means of CA, users gain access to a total bandwidth of up to 100 MHz in order to meet the IMT-Advanced requirements. The system bandwidth may be contiguous, or composed of several non-contiguous bandwidth chunks, which are a...

  8. Food proteins as potential carriers for phenolics

    NARCIS (Netherlands)

    Bohin, M.C.

    2013-01-01

    The development of phenolic-rich functional foods is often limited by the off-tastes of phenolics that might be counteracted by sequestering these compounds using a carrier, thereby preventing them to interact with bitter taste receptors and salivary proteins. A range of common animal food proteins

  9. A NEW SYNTHETIC FUNCTIONALIZED ANTIGEN CARRIER

    NARCIS (Netherlands)

    DRIJFHOUT, JW; BLOEMHOFF, W

    1991-01-01

    A new synthetic functionalized antigen carrier is described. It consists of a core of seven branched lysine residues, of which each of the four N-terminal lysine residues contains two N-(S-acetylmercaptoacetyl)-glutamyl residues. After removal of the protecting S-acetyl groups affording eight thiol

  10. Dextran: A promising macromolecular drug carrier

    Directory of Open Access Journals (Sweden)

    Dhaneshwar Suneela

    2006-01-01

    Full Text Available Over the past three decades intensive efforts have been made to design novel systems able to deliver the drug more effectively to the target site. The ongoing intense search for novel and innovative drug delivery systems is predominantly a consequence of the well-established fact that the conventional dosage forms are not sufficiently effective in conveying the drug compound to its site of action and once in the target area, in releasing the active agent over a desired period of time. The potential use of macromolecular prodrugs as a means of achieving targeted drug delivery has attracted considerable interest in recent years. Macromolecules such as antibodies, lipoproteins, lectins, proteins, polypeptides, polysaccharides, natural as well as synthetic polymers offer potential applicabilities as high molecular weight carriers for various therapeutically active compounds. Dextrans serve as one of the most promising macromolecular carrier candidates for a wide variety of therapeutic agents due to their excellent physico-chemical properties and physiological acceptance. The present contribution attempts to review various features of the dextran carrier like its source, structural and physico-chemical characteristics, pharmacokinetic fate and its applications as macromolecular carrier with special emphasis on dextran prodrugs.

  11. Roch Carrier, Popular Language, and Joual.

    Science.gov (United States)

    Walkley, Max

    1997-01-01

    Discusses the language problems in Roch Carrier's French Canadian short stories, as well as his concise, nostalgic writing style. The article gives examples of vocabulary in his characters' dialogue; reviews the evolvement of French in Quebec and the question of "joual," in particular; and focuses on expressions posing difficulty for…

  12. Polyester Dendrimers: Smart Carriers for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Jean–d’Amour K. Twibanire

    2014-01-01

    Full Text Available Polyester dendrimers have been shown to be outstanding candidates for biomedical applications. Compared to traditional polymeric drug vehicles, these biodegradable dendrimers show excellent advantages especially as drug delivery systems because they are non-toxic. Here, advances on polyester dendrimers as smart carriers for drug delivery applications have been surveyed. Both covalent and non-covalent incorporation of drugs are discussed.

  13. Hot Carrier Extraction from Multilayer Graphene.

    Science.gov (United States)

    Urcuyo, Roberto; Duong, Dinh Loc; Sailer, Patrick; Burghard, Marko; Kern, Klaus

    2016-11-09

    Hot carriers in semiconductor or metal nanostructures are relevant, for instance, to enhance the activity of oxide-supported metal catalysts or to achieve efficient photodetection using ultrathin semiconductor layers. Moreover, rapid collection of photoexcited hot carriers can improve the efficiency of solar cells, with a theoretical maximum of 85%. Because of the long lifetime of secondary excited electrons, graphene is an especially promising two-dimensional material to harness hot carriers for solar-to-electricity conversion. However, the photoresponse of thus far realized graphene photoelectric devices is mainly governed by thermal effects, which yield only a very small photovoltage. Here, we report a Gr-TiOx-Ti heterostructure wherein the photovoltaic effect is predominant. By doping the graphene, the open circuit voltage reaches values up to 0.30 V, 2 orders of magnitude larger than for devices relying upon the thermoelectric effect. The photocurrent turned out to be limited by trap states in the few-nanometer-thick TiOx layer. Our findings represent a first valuable step toward the integration of graphene into third-generation solar cells based upon hot carrier extraction.

  14. Microemulsions as Potential Carriers of Nisin

    DEFF Research Database (Denmark)

    Chatzidaki, Maria D; Papadimitriou, Konstantinos; Alexandraki, Voula

    2016-01-01

    Water-in-oil (W/O) microemulsions based on either refined olive oil (ROO) or sunflower oil (SO), distilled monoglycerides (DMG), and ethanol were used as nisin carriers in order to ensure its effectiveness as a biopreservative. This work presents experimental evidence on the effects of ethanol...

  15. Itaconic acid carrier ampholytes for isoelectric focusing.

    Science.gov (United States)

    Brenna, O

    1977-04-11

    Commercial carrier ampholytes, obtained by coupling polyethylene polyamines to acrylic acid, exhibit a conductivity minimum in the pH range 5.5-6.5 owing to the lack of appropriate pK values of the polyamine in this pH region. By replacing acrylic with itaconic acid, it has been possible to effect substantial improvements in the pH range 5.5-6.5 as itaconic acid has a pK2 value of 5.45. Upon coupling, the pK of the gramma-carboxyl group remains virtually unaltered. With itoconic acid carrier ampholytes it has been possible to improve the conductivity in the pH range 5.5-6.5 by as much as 400% compared with conventional carrier ampholytes. It is suggected that the commercial products should be supplemented with itaconic acid carrier ampholytes in order to obtain a more uniform conductivity and buffering capacity in the pH range 3-10.

  16. A universal thermal conductance of charge carriers

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, A.; Reggiani, L. [Lecce, Univ. (Italy). Ist. Nazionale di Fisica della Materia. Dipt. di Scienza dei Materiali; Kuhn, T. [Munster, Westfalische Wilhelms-Univ. (Germany). Inst. fur Theoretische Physik II; Varani, L. [Montpellier, Univ. Montpellier II (France). Centre d`Electronique et de Micro-optoelectronique

    1996-12-01

    A universal thermal conductance of charge carriers K = 2{pi}{sup 2}k{sub B}{sup 2}T / (3h) is rigorously derived within a correlation-function formalism. Similar to the case of the universal electrical conductance G = 2e{sup 2} / h this result pertains to one-dimensional, ballistic, and degenerate conditions for non-interacting particles.

  17. 7 CFR 35.4 - Carrier.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Carrier. 35.4 Section 35.4 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS EXPORT...

  18. Maximum Likelihood Timing and Carrier Synchronization in Burst-Mode Satellite Transmissions

    Directory of Open Access Journals (Sweden)

    Morelli Michele

    2007-01-01

    Full Text Available This paper investigates the joint maximum likelihood (ML estimation of the carrier frequency offset, timing error, and carrier phase in burst-mode satellite transmissions over an AWGN channel. The synchronization process is assisted by a training sequence appended in front of each burst and composed of alternating binary symbols. The use of this particular pilot pattern results into an estimation algorithm of affordable complexity that operates in a decoupled fashion. In particular, the frequency offset is measured first and independently of the other parameters. Timing and phase estimates are subsequently computed through simple closed-form expressions. The performance of the proposed scheme is investigated by computer simulation and compared with Cramer-Rao bounds. It turns out that the estimation accuracy is very close to the theoretical limits up to relatively low signal-to-noise ratios. This makes the algorithm well suited for turbo-coded transmissions operating near the Shannon limit.

  19. Maximum Likelihood Timing and Carrier Synchronization in Burst-Mode Satellite Transmissions

    Directory of Open Access Journals (Sweden)

    Michele Morelli

    2007-06-01

    Full Text Available This paper investigates the joint maximum likelihood (ML estimation of the carrier frequency offset, timing error, and carrier phase in burst-mode satellite transmissions over an AWGN channel. The synchronization process is assisted by a training sequence appended in front of each burst and composed of alternating binary symbols. The use of this particular pilot pattern results into an estimation algorithm of affordable complexity that operates in a decoupled fashion. In particular, the frequency offset is measured first and independently of the other parameters. Timing and phase estimates are subsequently computed through simple closed-form expressions. The performance of the proposed scheme is investigated by computer simulation and compared with Cramer-Rao bounds. It turns out that the estimation accuracy is very close to the theoretical limits up to relatively low signal-to-noise ratios. This makes the algorithm well suited for turbo-coded transmissions operating near the Shannon limit.

  20. Broadband midinfrared frequency comb with tooth scanning

    Science.gov (United States)

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

    2015-03-01

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

  1. Mechanisms of high-frequency song generation in brachypterous crickets and the role of ghost frequencies.

    Science.gov (United States)

    Robillard, Tony; Montealegre-Z, Fernando; Desutter-Grandcolas, Laure; Grandcolas, Philippe; Robert, Daniel

    2013-06-01

    Sound production in crickets relies on stridulation, the well-understood rubbing together of a pair of specialised wings. As the file of one wing slides over the scraper of the other, a series of rhythmic impacts causes harmonic oscillations, usually resulting in the radiation of pure tones delivered at low frequencies (2-8 kHz). In the short-winged crickets of the Lebinthini tribe, acoustic communication relies on signals with remarkably high frequencies (>8 kHz) and rich harmonic content. Using several species of the subfamily Eneopterinae, we characterised the morphological and mechanical specialisations supporting the production of high frequencies, and demonstrated that higher harmonics are exploited as dominant frequencies. These specialisations affect the structure of the stridulatory file, the motor control of stridulation and the resonance of the sound radiator. We placed these specialisations in a phylogenetic framework and show that they serve to exploit high-frequency vibrational modes pre-existing in the phylogenetic ancestor. In Eneopterinae, the lower frequency components are harmonically related to the dominant peak, suggesting they are relicts of ancestral carrier frequencies. Yet, such ghost frequencies still occur in the wings' free resonances, highlighting the fundamental mechanical constraints of sound radiation. These results support the hypothesis that such high-frequency songs evolved stepwise, by a form of punctuated evolution that could be related to functional constraints, rather than by only the progressive increase of the ancestral fundamental frequency.

  2. Frequency Stepped Pulse Train Modulated Wind Sensing Lidar

    DEFF Research Database (Denmark)

    Olesen, Anders Sig; Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2011-01-01

    In this paper a wind sensing lidar utilizing a Frequency Stepped Pulse Train (FSPT) is demonstrated. One of the advantages in the FSTP lidar is that it enables direct measurement of wind speed as a function of distance from the lidar. Theoretically the FSPT lidar continuously produces measurements...... as is the case with a CW lidar, but at the same time with a spatial resolution, and without the range ambiguity originating from e.g. clouds. The FSPT lidar utilizes a frequency sweeping source for generation of the FSPT. The source generates a pulse train where each pulse has an optical carrier frequency...... of frequency shifts corresponding to a specific distance. The spatial resolution depends on the repetition rate of the pulses in the pulse train. Directional wind measurements are shown and compared to a CW lidar measurement. The carrier to noise ratio of the FSPT lidar compared to a CW lidar is discussed...

  3. LWS/SET Technology Experiment Carrier

    Science.gov (United States)

    Sherman, Barry; Giffin, Geoff

    2002-01-01

    This paper examines the approach taken to building a low-cost, modular spacecraft bus that can be used to support a variety of technology experiments in different space environments. It describes the techniques used and design drivers considered to ensure experiment independence from as yet selected host spacecraft. It describes the technology experiment carriers that will support NASA's Living With a Star Space Environment Testbed space missions. NASA has initiated the Living With a Star (LWS) Program to develop a better scientific understanding to address the aspects of the connected Sun-Earth system that affect life and society. A principal goal of the program is to bridge the gap between science, engineering, and user application communities. The Space Environment Testbed (SET) Project is one element of LWS. The Project will enable future science, operational, and commercial objectives in space and atmospheric environments by improving engineering approaches to the accommodation and/or mitigation of the effects of solar variability on technological systems. The SET Project is highly budget constrained and must seek to take advantage of as yet undetermined partnering opportunities for access to space. SET will conduct technology validation experiments hosted on available flight opportunities. The SET Testbeds will be developed in a manner that minimizes the requirements for accommodation, and will be flown as flight opportunities become available. To access the widest range of flight opportunities, two key development requirements are to maintain flexibility with respect to accommodation constraints and to have the capability to respond quickly to flight opportunities. Experiments, already developed to the technology readiness level of needing flight validation in the variable Sun-Earth environment, will be selected on the basis of the need for the subject technology, readiness for flight, need for flight resources and particular orbit. Experiments will be

  4. Resistivity, carrier concentration, and carrier mobility of electrochemically deposited CdTe films

    OpenAIRE

    Takahashi, Makoto; Uosaki, Kohei; Kita, Hideaki; Yamaguchi, Shoji

    1986-01-01

    The electrical type, resistivity, and donor or acceptor concentration of CdTe films deposited electrochemically at various potentials were measured. The carrier mobilities of the films were determined from these results. The deposition potential dependence of the mobility was small and the deposition potential dependence of the resistivity was mainly controlled by the deposition potential dependence of the donor or acceptor concentration. The carrier mobilities were very small compared with t...

  5. Carrier screening for spinal muscular atrophy (SMA in 107,611 pregnant women during the period 2005-2009: a prospective population-based cohort study.

    Directory of Open Access Journals (Sweden)

    Yi-Ning Su

    Full Text Available BACKGROUND: Spinal muscular atrophy (SMA is the most common neuromuscular autosomal recessive disorder. The American College of Medical Genetics has recently recommended routine carrier screening for SMA because of the high carrier frequency (1 in 25-50 as well as the severity of that genetic disease. Large studies are needed to determine the feasibility, benefits, and costs of such a program. METHODS AND FINDINGS: This is a prospective population-based cohort study of 107,611 pregnant women from 25 counties in Taiwan conducted during the period January 2005 to June 2009. A three-stage screening program was used: (1 pregnant women were tested for SMA heterozygosity; (2 if the mother was determined to be heterozygous for SMA (carrier status, the paternal partner was then tested; (3 if both partners were SMA carriers, prenatal diagnostic testing was performed. During the study period, a total of 2,262 SMA carriers with one copy of the SMN1 gene were identified among the 107,611 pregnant women that were screened. The carrier rate was approximately 1 in 48 (2.10%. The negative predictive value of DHPLC coupled with MLPA was 99.87%. The combined method could detect approximately 94% of carriers because most of the cases resulted from a common single deletion event. In addition, 2,038 spouses were determined to be SMA carriers. Among those individuals, 47 couples were determined to be at high risk for having offspring with SMA. Prenatal diagnostic testing was performed in 43 pregnant women (91.49% and SMA was diagnosed in 12 (27.91% fetuses. The prevalence of SMA in our population was 1 in 8,968. CONCLUSION: The main benefit of SMA carrier screening is to reduce the burden associated with giving birth to an affected child. In this study, we determined the carrier frequency and genetic risk and provided carrier couples with genetic services, knowledge, and genetic counseling.

  6. A code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check codes

    Science.gov (United States)

    Bai, Cheng-lin; Cheng, Zhi-hui

    2016-09-01

    In order to further improve the carrier synchronization estimation range and accuracy at low signal-to-noise ratio ( SNR), this paper proposes a code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check (NB-LDPC) codes to study the polarization-division-multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system performance in the cases of quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) modes. The simulation results indicate that this algorithm can enlarge frequency and phase offset estimation ranges and enhance accuracy of the system greatly, and the bit error rate ( BER) performance of the system is improved effectively compared with that of the system employing traditional NB-LDPC code-aided carrier synchronization algorithm.

  7. Frequency noise in frequency swept fiber laser

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-01-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto...

  8. Frequency noise in frequency swept fiber laser.

    Science.gov (United States)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-04-01

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

  9. Carriers of multiresistant bacteria of clinical importance in critical areas (ICU - INCU

    Directory of Open Access Journals (Sweden)

    Aguilar Gamboa, Franklin Rómulo

    2016-03-01

    Full Text Available Objective: To determine the frequency of multiresistant bacteria Carriers (BM and its profile of resistance in critical areas (ICU-INCU in a public hospital in northern Peru (HRL. Material and methods: A cross-sectional observational study was conducted during February to May 2015, in 48 patients and 32 healthcare staff. 4 anatomical regions for sampling were considered and supplemented instruments with antibiotics were used for primary isolation of BM. The resistance phenotype was confirmed by Jailer's test, Modified Hodge and susceptibility to cefoxitin. Results: The frequencies of BM in patients and healthcare staff were 79.1% and 3.1% respectively; also 89.5% of patients were already carriers at the time of admission mainly from Emergency Service, being anorectal region the principal source of isolates with 75.0%. It also was determined that production of extended spectrum beta-lactamase (ESBL was the principal resistance phenotype with 77.65%, followed by the production of carbapenemases and methicillin resistance with 14.2% and 8.24% respectively. Conclusions: This study reveals the high frequency of multiresistant bacteria carriers in patients in critical areas of HRL and that most of these already were colonized in the anorectal region.

  10. Orthogonal frequency division multiplexing with diversity for future wireless systems

    CERN Document Server

    Le, Khoa N

    2012-01-01

    The book examines several aspects of Orthogonal Frequency Division Multiplexing (OFDM) employing linear diversity techniques such as inter-carrier interference, bit error rate, peak to average power and inter-block interference. It should be a useful reference for readers interested in modern wireless communication systems.

  11. Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit

    Directory of Open Access Journals (Sweden)

    Bin You

    2013-01-01

    Full Text Available A new ultrahigh frequency radio frequency identification (UHF RFID reader’s front-end circuit which is based on zero-IF, single antenna structure and composed of discrete components has been designed. The proposed design brings a significant improvement of the reading performance by adopting a carrier leakage suppression (CLS circuit instead of a circulator which is utilized by most of the conventional RF front-end circuit. Experimental results show that the proposed design improves both the sensitivity and detection range compared to the conventional designs.

  12. AURKA F31I Polymorphism and Breast Cancer Risk in BRCA1 and BRCA2 Mutation Carriers: A CIMBA study

    Science.gov (United States)

    Couch, Fergus J.; Sinilnikova, Olga; Vierkant, Robert A; Pankratz, V. Shane; Fredericksen, Zachary S.; Stoppa-Lyonnet, Dominique; Coupier, Isabelle; Hughes, David; Hardouin, Agnès; Berthet, Pascaline; Peock, Susan; Cook, Margaret; Baynes, Caroline; Hodgson, Shirley; Morrison, Patrick J.; Porteous, Mary E.; Jakubowska, Anna; Lubinski, Jan; Gronwald, Jacek; Spurdle, Amanda B.; Schmutzler, Rita; Versmold, Beatrix; Engel, Christoph; Meindl, Alfons; Sutter, Christian; Horst, Jurgen; Schaefer, Dieter; Offit, Kenneth; Kirchhoff, Tomas; Andrulis, Irene L.; Ilyushik, Eduard; Glendon, Gordon; Devilee, Peter; Vreeswijk, Maaike P.G.; Vasen, Hans F.A.; Borg, Ake; Backenhorn, Katja; Struewing, Jeffery P.; Greene, Mark H.; Neuhausen, Susan L.; Rebbeck, Timothy R.; Nathanson, Katherine; Domchek, Susan; Wagner, Theresa; Garber, Judy E.; Szabo, Csilla; Zikan, Michal; Foretova, Lenka; Olson, Janet E.; Sellers, Thomas A.; Lindor, Noralane; Nevanlinna, Heli; Tommiska, Johanna; Aittomaki, Kristiina; Hamann, Ute; Rashid, Muhammad U.; Torres, Diana; Simard, Jacques; Durocher, Francine; Guenard, Frederic; Lynch, Henry T.; Isaacs, Claudine; Weitzel, Jeffrey; Olopade, Olufunmilayo I.; Narod, Steven; Daly, Mary B.; Godwin, Andrew K.; Tomlinson, Gail; Easton, Douglas F.; Chenevix-Trench, Georgia; Antoniouon, Antonis C.

    2009-01-01

    The AURKA oncogene is associated with abnormal chromosome segregation and aneuploidy and predisposition to cancer. Amplification of AURKA has been detected at higher frequency in tumors from BRCA1 and BRCA2 mutation carriers than in sporadic breast tumors, suggesting that overexpression of AURKA and inactivation of BRCA1 and BRCA2 co-operate during tumor development and progression. The F31I polymorphism in AURKA has been associated with breast cancer risk in the homozygous state in prior studies. We evaluated whether the AURKA F31I polymorphism modifies breast cancer risk in BRCA1 and BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). CIMBA was established to provide sufficient statistical power through increased numbers of mutation carriers to identify polymorphisms that act as modifiers of cancer risk and can refine breast cancer risk estimates in BRCA1 and BRCA2 mutation carriers. A total of 4935 BRCA1 and 2241 BRCA2 mutation carriers and 11 individuals carrying both BRCA1 and BRCA2 mutations were genotyped for F31I. Overall, homozygosity for the 31I allele was not significantly associated with breast cancer risk in BRCA1 and BRCA2 carriers combined (HR = 0.91; 95% CI 0.77-1.06). Similarly, no significant association was seen in BRCA1 (HR = 0.90; 95% CI 0.75-1.08) or BRCA2 carriers (HR = 0.93; 95% CI 0.67-1.29) or when assessing the modifying effects of either bilateral prophylactic oophorectomy or menopausal status of BRCA1 and BRCA2 carriers. In summary, the F31I polymorphism in AURKA is not associated with a modified risk of breast cancer in BRCA1 and BRCA2 carriers. PMID:17627006

  13. Frequency synchronization scheme for parasitical BiSAR with GNSS satellites as illuminator

    Science.gov (United States)

    Tian, Weiming; Zeng, Tao; Hu, Cheng

    Bistatic Synthetic Aperture Radar (BiSAR) has a lot of advantages comparing with monostatic counterpart. What is more, parasitical BiSAR can utilize the existing Global Navigation Satel-lite System (GNSS) satellites to compose parasitical BiSAR system and form remote-sensing image. As performance of frequency synchronization scheme is crucial to BiSAR system, fre-quency synchronization scheme must be well designed. In fact high-precision frequency syn-chronization is required to obtain navigation data and assist positioning in GNSS receiver. In GNSS receivers, transient carrier frequency is tracked by digital Phase-Locked Loop (PLL). PLL method is applied to estimate frequency synchronization error and this has been verified in the primary experiment. Through tracking the carrier transient frequency of direct signal, frequency synchronization error can be obtained from the transient frequency when theoretical Doppler is calculated from ephemeris data.

  14. Phase generated carrier technique for fiber laser hydrophone

    Science.gov (United States)

    Li, Rizhong; Wang, Xinbing; Huang, Junbin; Gu, Hongcan

    2013-08-01

    A distributed feedback (DFB) fiber laser is compact, and is very suitable for using as a hydrophone to sense acoustic pressure. A DFB fiber laser hydrophone was researched. In the fiber laser hydrophone signal demodulating system, an unbalanced Michelson fiber interferometer and a Phase Generated Carrier (PGC) method were used. The PGC method can be used to demodulating the acoustic signal from the interference signal. Comparing with the Naval Research Laboratory (NRL) method and Naval Postgraduate School (NPS) method, the digitized PGC method requires a greater amount of computation because of the high signal sampling, but it demands only one interference signal which makes the less fiber connections of the fiber laser hydrophone array. So the fiber laser hydrophone array based on the PGC method has lower complexity and higher reliability than that based on the NRL method or NPS method. The experimental results approve that the PGC method can demodulate acoustic signal between 20~2000 Hz frequency range with good signal-to-noise ratio (SNR) when the PZT driving frequency is 20 kHz.

  15. Spatially dispersive dynamical response of hot carriers in doped graphene

    Science.gov (United States)

    Kukhtaruk, S. M.; Kochelap, V. A.; Sokolov, V. N.; Kim, K. W.

    2016-05-01

    We study theoretically wave-vector and frequency dispersion of the complex dynamic conductivity tensor (DCT), σlm(k , ω), of doped monolayer graphene under a strong dc electric field. For a general analysis, we consider the weak ac field of arbitrary configuration given by two independent vectors, the ac field polarization and the wave vector k. The high-field transport and linear response to the ac field are described on the base of the Boltzmann kinetic equation. We show that the real part of DCT, calculated in the collisionless regime, is not zero due to dissipation of the ac wave, whose energy is absorbed by the resonant Dirac quasiparticles effectively interacting with the wave. The role of the kinematic resonance at ω =vF | k | (vF is the Fermi velocity) is studied in detail taking into account deviation from the linear energy spectrum and screening by the charge carriers. The isopower-density curves and distributions of angle between the ac current density and field vectors are presented as a map which provides clear graphic representation of the DCT anisotropy. Also, the map shows certain ac field configurations corresponding to a negative power density, thereby it indicates regions of terahertz frequency for possible electrical (drift) instability in the graphene system.

  16. Illness perceptions, risk perception and worry in SDH mutation carriers

    NARCIS (Netherlands)

    Hulsteijn, L.T. van; Kaptein, A.A.; Louisse, A.; Biermasz, N.R.; Smit, J.W.; Corssmit, E.P.

    2014-01-01

    Succinate dehydrogenase (SDH) mutation carriers are predisposed for developing paragangliomas. This study aimed to explore illness perceptions, risk perception and disease-related worry in these individuals. All consecutive SDHB and SDHD mutation carriers followed at the Department of Endocrinology

  17. 48 CFR 1615.470 - Carrier investment of FEHB funds.

    Science.gov (United States)

    2010-10-01

    ... CONTRACTING BY NEGOTIATION Contract Pricing 1615.470 Carrier investment of FEHB funds. (a) Except for contracts based on a combination of cost and price analysis (community-rated), the carrier is required to...

  18. Effective Carrier Sensing in CSMA Networks under Cumulative Interference

    CERN Document Server

    Fu, Liqun; Huang, Jianwei

    2009-01-01

    This paper proposes and investigates the concept of a safe carrier-sensing range that can guarantee interference safe (also termed hidden-node-free) transmissions in CSMA networks under the cumulative interference model. Compared with the safe carrier-sensing range under the commonly assumed but less realistic pairwise interference model, we show that the safe carrier-sensing range required under the cumulative interference model is larger by a constant multiplicative factor. The concept of a safe carrier-sensing range, although amenable to elegant analytical results, is inherently not compatible with the conventional power threshold carrier-sensing mechanism (e.g., that used in IEEE 802.11). Specifically, the absolute power sensed by a node in the conventional mechanism does not contain enough information for it to derive its distances from other concurrent transmitter nodes. We show that, fortunately, a carrier-sensing mechanism called Incremental-Power Carrier-Sensing (IPCS) can realize the carrier-sensing...

  19. DETECTION OF COMPLEXES OLIGODEOXYNUCLEOTIDES WITH POLYMERIC CARRIERS

    Directory of Open Access Journals (Sweden)

    V. V. Vlizlo

    2013-10-01

    Full Text Available The new method for detection of cationic oligoelectrolytes conjugates with oligodeoxyonucleotides, based on free diffusion of these substances in 0.8% agarose gels is developed. It enables to simplify and reduce the cost of visual identification of the best carrier among various polymer compounds and to uncover the fact of complex formation between the interacting agents resulting in formation of a ring precipitation. The universality of the proposed methodological approach is confirmed by interaction of coligodeoxynucleotides with other cationic polymer of natural origin, namely chitosan. Comparative analysis of our approach applicationto turbidimetry data concerning coligodeoxynucleotides complexes and their electrophoresis showed some advantages, among them are the ability to screen simultaneously a large number of polymeric carriers and no need for using of more expensive equipment and materials. To conclude the complexing occurrence it is enough nanomol amounts of oligodeoxynucleotide.

  20. Solid lipid nanoparticles: A drug carrier system

    Directory of Open Access Journals (Sweden)

    Rashmi R Kokardekar

    2011-01-01

    Full Text Available Solid lipid nanoparticles (SLN are a type of nanoparticles. They are submicron colloidal carriers which are composed of physiological lipids, dispersed in water or in aqueous surfactant solutions. SLN have wide range of advantages over other types of nanoparticles. These include availability of large-scale production methods and no signs of cytotoxicity, which are main hindrances in the application of other types of nanoparticles. Hot and cold homogenization techniques are mainly employed for its production. They are mainly evaluated on the basis of their drug release profile and particle internal structure. The products based on SLN are under development. They have a very wide range of applications in cosmetics and pharmaceuticals. They can be applied for any purpose, for which nanoparticles have a distinct advantage. Thus, SLN can be used extensively as an alternative to the existing drug carrier systems, providing more flexibility with respect to the area of applications and also aspects for commercialization.

  1. Controlling carrier dynamics at the nanoscale

    Science.gov (United States)

    Cánovas, Enrique; Bonn, Mischa

    2016-10-01

    This Special issue is motivated by the occasion of the International Conference on Charge Carrier Dynamics at the Nanoscale (CCDNano), held in Santiago de Compostela (Spain) in September 2015. As chairs for the CCDNano meeting, we aimed at bringing together experts from different scientific fields in order to trigger interdisciplinary discussions and collaborations; the ultimate goal of the conference was to serve as a platform to advance and help unifying methodologies and theories from different research sub-fields. We also aimed at a deeper understanding of charge dynamics to contribute to the development of improved or novel nanostructured devices. This special issue keeps that spirit, and intends to provide an overview of ongoing research efforts regarding charge carrier dynamics at the nanoscale.

  2. Superconductivity in carrier-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Takahiro Muranaka, Yoshitake Kikuchi, Taku Yoshizawa, Naoki Shirakawa and Jun Akimitsu

    2008-01-01

    Full Text Available We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm−3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  3. Energy carriers in Norway; Energibaerere i Norge

    Energy Technology Data Exchange (ETDEWEB)

    2008-01-15

    Within the Norwegian energy consumption, electricity is by far the most dominant energy carrier. In the last thirty years electricity has had an increased significance, while oil has been reduce. A trend that is likely to continue. Energy politics has among others these objectives: environment, reliability of supply and effective energy supply. These objectives are somewhat contradictory. In agreement with the environmental politic phasing out oil leads to a reduction in greenhouse gases. However this politic will have a local impact only effecting Norway, in a larger European connection it might lead to a larger net emission of CO{sub 2}. A political intervention in the energy market might also lead to a reduction in the energy markets effectiveness and flexibility. This report addresses this problem: If a total phase out of the stationary oil consumption is conducted, what energy carriers will this consumption convert to?

  4. Experimental distribution of entanglement with separable carriers.

    Science.gov (United States)

    Fedrizzi, A; Zuppardo, M; Gillett, G G; Broome, M A; Almeida, M P; Paternostro, M; White, A G; Paterek, T

    2013-12-01

    The key requirement for quantum networking is the distribution of entanglement between nodes. Surprisingly, entanglement can be generated across a network without direct transfer-or communication-of entanglement. In contrast to information gain, which cannot exceed the communicated information, the entanglement gain is bounded by the communicated quantum discord, a more general measure of quantum correlation that includes but is not limited to entanglement. Here, we experimentally entangle two communicating parties sharing three initially separable photonic qubits by exchange of a carrier photon that is unentangled with either party at all times. We show that distributing entanglement with separable carriers is resilient to noise and in some cases becomes the only way of distributing entanglement through noisy environments.

  5. Multi-carrier Communications over Time-varying Acoustic Channels

    Science.gov (United States)

    Aval, Yashar M.

    Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple

  6. Yeast ADP/ATP Carrier Isoform 2

    Science.gov (United States)

    Clémençon, Benjamin; Rey, Martial; Trézéguet, Véronique; Forest, Eric; Pelosi, Ludovic

    2011-01-01

    The mitochondrial ADP/ATP carrier, or Ancp, is a member of the mitochondrial carrier family responsible for exchanging ADP and ATP across the mitochondrial inner membrane. ADP/ATP transport involves Ancp switching between two conformational states. These can be analyzed using specific inhibitors, carboxyatractyloside (CATR) and bongkrekic acid (BA). The high resolution three-dimensional structure of bovine Anc1p (bAnc1p), as a CATR-carrier complex, has been solved. However, because the structure of the BA-carrier complex has not yet been determined, the detailed mechanism of transport remains unknown. Recently, sample processing for hydrogen/deuterium exchange experiments coupled to mass spectrometry was improved, providing novel insights into bAnc1p conformational transitions due to inhibitor binding. In this work we performed both hydrogen/deuterium exchange-mass spectrometry experiments and genetic manipulations. Because these are very difficult to apply with bovine Anc1p, we used Saccharomyces cerevisiae Anc isoform 2 (ScAnc2p). Significant differences in solvent accessibility were observed throughout the amino acid sequence for ScAnc2p complexed to either CATR or BA. Interestingly, in detergent solution, the conformational dynamics of ScAnc2p were dissimilar to those of bAnc1p, in particular for the upper half of the cavity, toward the intermembrane space, and the m2 loop, which is thought to be easily accessible to the solvent from the matrix in bAnc1p. Our study then focused on the methionyl residues of the Ancp signature sequence, RRRMMM. All our results indicate that the methionine cluster is involved in the ADP/ATP transport mechanism and confirm that the Ancp cavity is a highly dynamic structure. PMID:21868387

  7. Leasing in low-cost carriers

    OpenAIRE

    Aleixo, José Frederico Pais

    2014-01-01

    The aim of this paper is to explore the use of aircraft leasing as a financing instrument in the low-cost carriers’ sector. These airlines have been showing a huge growth in the customers’ preferences, while aircraft leasing plays a relevant role in the financing options of airlines. In this study we determined that lease future commitments represent on average 80% of other debt commitments in low-cost carriers. Furthermore, we discovered that the leasing rate in low-cost ai...

  8. Polymeric micellar drug carriers with fluorescent properties

    OpenAIRE

    Abreu, Ana Sofia Lemos Machado; Sá, Arsénio Vasconcelos; Oliveira, Manuel; Moura, I; Machado, A.V.

    2015-01-01

    Self-assembling polymeric surfactants, based on amphiphilic block copolymers into nanosized aggregates in aqueous solution, are of great interest in the biomedical fields as one class of promising carrier systems, for drug delivery, gene therapy and diagnostic biosensors.[1] The incorporation of fluorescent probes into polymeric micelles has been fulfilled either by physically encapsulation or chemically attachment of fluorophores. [2] These micelle-based fluorescent probes not only facili...

  9. Formic Acid as a Hydrogen Energy Carrier

    KAUST Repository

    Eppinger, Jorg

    2016-12-15

    The high volumetric capacity (S3 g H-2/L) and its low toxicity and flammability under ambient conditions make formic acid a promising hydrogen energy carrier. Particularly, in the past decade, significant advancements have been achieved in catalyst development for selective hydrogen generation from formic acid. This Perspective highlights the advantages of this approach with discussions focused on potential applications in the transportation sector together with analysis of technical requirements, limitations, and costs.

  10. Commercial Air Carrier Vulnerabilities to Information Operations

    Science.gov (United States)

    2007-11-02

    GMO /ENS/02E-11 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio...AFIT/ GMO /ENS/02E-11 COMMERCIAL AIR CARRIER VULNERABILITIES TO INFORMATION OPERATIONS...networks that without them, “there is no water coming out of your tap; there is no electricity lighting your room; there is no food being transported to

  11. Carrier-free, continuous primary beer fermentation

    OpenAIRE

    Pires, Eduardo J.; Teixeira, J. A; Brányik, Tomáš; A.A. Vicente

    2014-01-01

    Developing a sustainable continuous fermentation reactor is one of the most ambitious tasks in brewing science, but it could bring great benefits regarding volumetric productivity to modern breweries. Immobilized cell technology is often applied to reach the large densities of yeast needed in a continuous fermentation process. However, the financial cost associated with the use of carriers for yeast immobilization is one of the major drawbacks in the technology. This work suggests that yeast ...

  12. Electrolyte-Gated Graphene Ambipolar Frequency Multipliers for Biochemical Sensing.

    Science.gov (United States)

    Fu, Wangyang; Feng, Lingyan; Mayer, Dirk; Panaitov, Gregory; Kireev, Dmitry; Offenhäusser, Andreas; Krause, Hans-Joachim

    2016-04-13

    In this Letter, the ambipolar properties of an electrolyte-gated graphene field-effect transistor (GFET) have been explored to fabricate frequency-doubling biochemical sensor devices. By biasing the ambipolar GFETs in a common-source configuration, an input sinusoidal voltage at frequency f applied to the electrolyte gate can be rectified to a sinusoidal wave at frequency 2f at the drain electrode. The extraordinary high carrier mobility of graphene and the strong electrolyte gate coupling provide the graphene ambipolar frequency doubler an unprecedented unity gain, as well as a detection limit of ∼4 pM for 11-mer single strand DNA molecules in 1 mM PBS buffer solution. Combined with an improved drift characteristics and an enhanced low-frequency 1/f noise performance by sampling at doubled frequency, this good detection limit suggests the graphene ambipolar frequency doubler a highly promising biochemical sensing platform.

  13. Steering optical comb frequency by rotating polarization state

    CERN Document Server

    Zhang, Y; Zhang, X F; Zhang, L; Han, W; Guo, W; Jiang, H; Zhang, S

    2016-01-01

    Optical frequency combs, with precise control of repetition rate and carrier-envelope-offset frequency, have revolutionized many fields, such as fine optical spectroscopy, optical frequency standards, ultra-fast science research, ultra-stable microwave generation and precise ranging measurement. However, existing high bandwidth frequency control methods have small dynamic range, requiring complex hybrid control techniques. To overcome this limitation, we develop a new approach, where a home-made intra-cavity electro-optic modulator tunes polarization state of laser signal rather than only optical length of the cavity, to steer frequencies of a nonlinear-polarization-rotation mode-locked laser. By taking advantage of birefringence of the whole cavity, this approach results in not only broadband but also relative large-dynamic frequency control. Experimental results show that frequency control dynamic range increase at least one order in comparison with the traditional intra-cavity electro-optic modulator techn...

  14. Photoinduced carrier annihilation in silicon pn junction

    Science.gov (United States)

    Sameshima, Toshiyuki; Motoki, Takayuki; Yasuda, Keisuke; Nakamura, Tomohiko; Hasumi, Masahiko; Mizuno, Toshihisa

    2015-08-01

    We report analysis of the photo-induced minority carrier effective lifetime (τeff) in a p+n junction formed on the top surfaces of a n-type silicon substrate by ion implantation of boron and phosphorus atoms at the top and bottom surfaces followed by activation by microwave heating. Bias voltages were applied to the p+ boron-doped surface with n+ phosphorus-doped surface kept at 0 V. The values of τeff were lower than 1 × 10-5 s under the reverse-bias condition. On the other hand, τeff markedly increased to 1.4 × 10-4 s as the forward-bias voltage increased to 0.7 V and then it leveled off when continuous-wave 635 nm light was illuminated at 0.74 mW/cm2 on the p+ surface. The carrier annihilation velocity S\\text{p + } at the p+ surface region was numerically estimated from the experimental τeff. S\\text{p + } ranged from 4000 to 7200 cm/s under the reverse-bias condition when the carrier annihilation velocity S\\text{n + } at the n+ surface region was assumed to be a constant value of 100 cm/s. S\\text{p + } markedly decreased to 265 cm/s as the forward-bias voltage increased to 0.7 V.

  15. Parametric frequency transformation in a superconducting waveguide line with an integrated Josephson oscillator

    Science.gov (United States)

    Denisenko, M. V.; Munyaev, V. O.; Satanin, A. M.

    2016-11-01

    The parametric frequency division in a coplanar waveguide line with an integrated single-contact rf SQUID (Josephson oscillator) is discussed. It is assumed that the oscillator is excited by pump pulses whose carrier frequency can be a multiple of the plasma frequency of the oscillator. It is shown that the Josephson oscillator excited at the pump frequency can induce frequency division by emitting subharmonics that are multiples of the fundamental frequency (fractional resonances). Parameters for which parametric frequency transformation occurs are determined. The possible generalization of this effect to the quantum case in which correlated microwave photons (entangled photon states) can be generated is discussed.

  16. Electric force microscopy of semiconductors: Theory of cantilever frequency fluctuations and noncontact friction

    Energy Technology Data Exchange (ETDEWEB)

    Lekkala, Swapna; Marohn, John A.; Loring, Roger F., E-mail: roger.loring@cornell.edu [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

    2013-11-14

    An electric force microscope employs a charged atomic force microscope probe in vacuum to measure fluctuating electric forces above the sample surface generated by dynamics of molecules and charge carriers. We present a theoretical description of two observables in electric force microscopy of a semiconductor: the spectral density of cantilever frequency fluctuations (jitter), which are associated with low-frequency dynamics in the sample, and the coefficient of noncontact friction, induced by higher-frequency motions. The treatment is classical-mechanical, based on linear response theory and classical electrodynamics of diffusing charges in a dielectric continuum. Calculations of frequency jitter explain the absence of contributions from carrier dynamics to previous measurements of an organic field effect transistor. Calculations of noncontact friction predict decreasing friction with increasing carrier density through the suppression of carrier density fluctuations by intercarrier Coulomb interactions. The predicted carrier density dependence of the friction coefficient is consistent with measurements of the dopant density dependence of noncontact friction over Si. Our calculations predict that in contrast to the measurement of cantilever frequency jitter, a noncontact friction measurement over an organic semiconductor could show appreciable contributions from charge carriers.

  17. [Heterogeneity in phage sensitivity in populations of S. aureus vegetating in patients and carriers].

    Science.gov (United States)

    Adarchenko, A A

    1977-12-01

    It was found that the S. aureus populations vegetating in patients and carriers were heterogeneous by phagegroup reference of the strains isolated in 31.1 and 23.9% of cases, respectively, and in 35.9 and 26.9%--phagovars. The frequency and the extent of variability of the populations in the patients depended on the character of the disease, the site of infection and the association of the focus with the external environment, and in carriers--on the localization and the carrier category. S. aureus populations habituating in the patients with the primary purulent processes and mastitis, as in the closed processes and in cases of extrahospital infection consisted, with rare exception, of the strains of one phagovar. In a considerable number of patients with purulent processes after the incision (38.0%), with infected wounds (37.2%), and particularly with burns (78.6%) of the S. aureus population consisted of 2, 3 and even 4 phagovars. Variable were also populations vegetating in patients with open processes (47.1%) and in hospital (26.5%) and mixed infection (52.6%). The phage-type composition of the S. aureus populations in carriers was also characterized by heterogeneity, which was more pronounced in chronic carriers and in case of localization of the processes in the nose. On the basis of the data obtained the minimal number of cultures which should be studied from the microbial focus in order to obtain objective data on the composition of phagovars in the population of various categories of patients and carriers was calculated.

  18. Time Resolved Studies of Carrier Dynamics in III -v Heterojunction Semiconductors.

    Science.gov (United States)

    Westland, Duncan James

    Available from UMI in association with The British Library. Requires signed TDF. Picosecond time-resolution photoluminescence spectroscopy has been used to study transient processes in Ga _{.47}In_{.53 }As/InP multiple quantum wells (MQWs), and in bulk Ga_{.47}In _{.53}As and GaSb. To facilitate the experimental studies, apparatus was constructed to allow the detection of transient luminescence with 3ps time resolution. A frequency upconversion technique was employed. Relaxation of energetic carriers in bulk Ga _{.47}In_{.53 }As by optic phonons has been investigated, and, at carrier densities ~3 times 10^{18}cm ^{-3} is found to be a considerably slower process than simple theory predicts. The discrepancy is resolved by the inclusion of a non-equilibrium population of longitudinal optic phonons in the theoretical description. Slow energy loss is also observed in a 154A MQW under similar conditions, but carriers are found to relax more quickly in a 14A MQW with a comparable repeat period. The theory of non-equilibrium mode occupation is modified to describe the case of a MQW and is found to agree with experiment. Carrier relaxation in GaSb is studied and the importance of occupation of the L _6 conduction band valley in this material is demonstrated. The ambipolar diffusion of a photoexcited carrier plasma through an InP capping layer was investigated using an optical time-of-flight technique. This experiment also enables the efficiency of carrier capture by a Ga _{.47}In_{.53 }As quantum well to be determined. A capture time of 4ps was found.

  19. 49 CFR 373.101 - Motor carrier bills of lading.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Motor carrier bills of lading. 373.101 Section 373.101 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS RECEIPTS...

  20. 14 CFR 252.3 - Smoking ban: air carriers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Smoking ban: air carriers. 252.3 Section... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.3 Smoking ban: air carriers. Air carriers shall prohibit smoking on all scheduled passenger flights....

  1. 14 CFR 252.5 - Smoking ban: foreign air carriers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Smoking ban: foreign air carriers. 252.5... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.5 Smoking ban: foreign air carriers. (a) Foreign air carriers shall prohibit smoking on all scheduled passenger flight segments: (1) Between...

  2. Terahertz carrier dynamics in graphene and graphene nanostructures

    DEFF Research Database (Denmark)

    Jensen, Søren A.; Turchinovich, Dmitry; Tielrooij, Klaas Jan

    2014-01-01

    Photoexcited charge carriers in 2D graphene and in 1D graphene nanostructures were studied with optical pump-THz probe spectroscopy. We find efficient hot-carrier multiplication in 2D graphene, and predominantly free carrier early time response in 1D nanostructures. © 2014 OSA....

  3. Carrier peptide-mediated transepithelial permeation of biopharmaceuticals

    DEFF Research Database (Denmark)

    Kristensen, Mie; Nielsen, Hanne Mørck

    2015-01-01

    of the molar mixing ratio between the carrier peptide and the therapeutic cargo, whereas the direct conjugation approach ensures an inherent proximity of the carrier peptide to its therapeutic cargo. So far studies addressing the choice of using the co-administration approach over the conjugation approach......-34)) and the widely studied CPP penetratin were employed as therapeutic cargo and carrier peptide, respectively....

  4. Terahertz carrier dynamics in graphene and graphene nanostructures

    DEFF Research Database (Denmark)

    Jensen, Søren A.; Turchinovich, Dmitry; Tielrooij, Klaas Jan

    2014-01-01

    Photoexcited charge carriers in 2D graphene and in 1D graphene nanostructures were studied with optical pump-THz probe spectroscopy. We find efficient hot-carrier multiplication in 2D graphene, and predominantly free carrier early time response in 1D nanostructures. © 2014 OSA....

  5. 19 CFR 18.2 - Receipt by carrier; manifest.

    Science.gov (United States)

    2010-04-01

    ... TREASURY TRANSPORTATION IN BOND AND MERCHANDISE IN TRANSIT General Provisions § 18.2 Receipt by carrier... Carrier (or Exporter) Attorney-in-fact or Agent of Carrier (or Exporter) Date (3) Merchandise delivered... prescribed in subpart D of part 123 of this chapter, relating to merchandise in transit through the...

  6. Joint Iterative Carrier Synchronization and Signal Detection for Dual Carrier 448 Gb/s PDM 16-QAM

    DEFF Research Database (Denmark)

    Zibar, Darko; Carvalho, Luis; Estaran Tolosa, Jose Manuel

    2013-01-01

    Soft decision driven joint carrier synchronization and signal detection, employing expectation maximization, is experimentally demonstrated. Employing soft decisions offers an improvement of 0.5 dB compared to hard decision digital PLL based carrier synchronization and demodulation....

  7. Literature review of the passenger airline business models: Full service carrier, low-cost carrier and charter airlines

    NARCIS (Netherlands)

    Carmona Benitez, R.B.; Lodewijks, G.

    2008-01-01

    The deregulation and liberalization of the air transportation industry have developed three main passenger business models: full service carriers, low-cost carriers, and charter airlines. Deregulation removed regulated fares and routes increasing competition and yields. Airlines business models main

  8. Literature review of the passenger airline business models: Full service carrier, low-cost carrier and charter airlines

    NARCIS (Netherlands)

    Carmona Benitez, R.B.; Lodewijks, G.

    2008-01-01

    The deregulation and liberalization of the air transportation industry have developed three main passenger business models: full service carriers, low-cost carriers, and charter airlines. Deregulation removed regulated fares and routes increasing competition and yields. Airlines business models main

  9. Comprehensive approach to intrinsic charge carrier mobility in conjugated organic molecules, macromolecules, and supramolecular architectures.

    Science.gov (United States)

    Saeki, Akinori; Koizumi, Yoshiko; Aida, Takuzo; Seki, Shu

    2012-08-21

    (-1) s(-1), based on a combination of flash-photolysis TRMC and transient absorption spectroscopy (TAS) measurements. Single-crystal rubrene showed an ambipolarity with anisotropic charge carrier transport along each crystal axis on the nanometer scale. Finally, we describe the charge carrier mobility of a self-assembled nanotube consisting of a large π-plane of hexabenzocoronene (HBC) partially appended with an electron acceptor. The local (intratubular) charge carrier mobility reached 3 cm(2) V(-1) s(-1) for the nanotubes that possessed well-ordered π-stacking, but it dropped to 0.7 cm(2) V(-1) s(-1) in regions that contained greater amounts of the electron acceptor because those molecules reduced the structural integrity of π-stacked HBC arrays. Interestingly, the long-range (intertubular) charge carrier mobility was on the order of 10(-4) cm(2) V(-1) s(-1) and monotonically decreased when the acceptor content was increased. These results suggest the importance of investigating charge carrier mobilities by frequency-dependent charge carrier motion for the development of more efficient organic electronic devices.

  10. Solid lipid nanoparticles and nanostructured lipid carriers--innovative generations of solid lipid carriers.

    Science.gov (United States)

    Shidhaye, S S; Vaidya, Reshma; Sutar, Sagar; Patwardhan, Arati; Kadam, V J

    2008-10-01

    The first generation of solid lipid carrier systems in nanometer range, Solid Lipid Nanoparticles (SLN), was introduced as an alternative to liposomes. SLN are aqueous colloidal dispersions, the matrix of which comprises of solid biodegradable lipids. SLN are manufactured by techniques like high pressure homogenization, solvent diffusion method etc. They exhibit major advantages such as modulated release, improved bioavailability, protection of chemically labile molecules like retinol, peptides from degradation, cost effective excipients, improved drug incorporation and wide application spectrum. However there are certain limitations associated with SLN, like limited drug loading capacity and drug expulsion during storage, which can be minimized by the next generation of solid lipids, Nanostructured lipid carriers (NLC). NLC are lipid particles with a controlled nanostructure that improves drug loading and firmly incorporates the drug during storage. Owing to their properties and advantages, SLN and NLC may find extensive application in topical drug delivery, oral and parenteral administration of cosmetic and pharmaceutical actives. Cosmeceuticals is emerging as the biggest application target of these carriers. Carrier systems like SLN and NLC were developed with a perspective to meet industrial needs like scale up, qualification and validation, simple technology, low cost etc. This paper reviews present status of SLN and NLC as carrier systems with special emphasis on their application in Cosmeceuticals; it also gives an overview about various manufacturing techniques of SLN and NLC.

  11. Theoretical study of low-frequency noise and amplitude – frequency characteristics of a semiconductor laser with a fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Kurnosov, V D; Kurnosov, K V [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2013-09-30

    Using the rate equations for the density of photons and charge carriers, we have studied the amplitude low-frequency noise of a fibre Bragg grating semiconductor laser. The calculations rely on two versions of the rate equation for the carriers, characterised by the presence of the optical confinement coefficient for the term, which takes into account the rate of stimulated recombination. It is shown that the relative noise intensity, which is calculated by using the rate equation for the carriers without optical confinement, agrees better with the experimental results. The calculation of the amplitude – frequency characteristics (AFCs) has shown that it is impossible to give preference to any one of these systems, since the AFCs for the two versions of the rate equations for the carriers coincide. (lasers)

  12. Do methicillin resistant staphylococcus (MRSA) carrier patients influence MRSA infection more than MRSA-carrier medical officers and MRSA-carrier family?

    Science.gov (United States)

    Dilogo, Ismail H; Arya, Abikara; Phedy; Loho, Tony

    2013-07-01

    to determine the rate of MRSA-carrier among patients, family members and health care providers, and the association between MRSA-carrier family members and health care providers on MRSA infection patient after orthopaedic surgery. this is a cross-sectional analytical study. Samples were taken consecutively during December 2010 to December 2011, consisting of postoperative patients infected with MRSA, attending family members, and the medical officers with history of contact with the patient. Swab culture were taken from nasal and axilla of all subjects. The incidence of MRSA infection, and MRSA-carrier on the patient, family members and medical officers were presented descriptively, while their association with MRSA infection was statistically tested using Fischer exact test. during the study period, there were 759 surgeries, with 4 (0.5%) patients were identified to have MRSA infection. Of these four cases, 48 subjects were enrolled. The rate of MRSA-carrier among patients, family and health care providers were 50%, 25% and 0% respectively. There were no significant association between MRSA and the rates of MRSA-carrier on the family member or health care providers. the incidence of MRSA infection, MRSA-carrier patient, MRSA-carrier health care providers, and family member carrier were 0.5%, 50%, 0%, and 25% respectively. No significant association found between MRSA-carrier on the family member or health care providers and MRSA infection patient. There were no MRSA infection found on the health care provider.

  13. Sleuthing the MSL EDL Performance from an X Band Carrier Perspective

    Science.gov (United States)

    Oudrhiri, Kamal; Asmar, Sami; Estabrook, Polly; Kahan, Daniel; Mukai, Ryan; Ilott, Peter; Schratz, Brian; Soriano, Melissa; Finley, Susan; Shidner, Jeremy

    2013-01-01

    During the Entry, Descent, and Landing (EDL) of NASA's Mars Science Laboratory (MSL), or Curiosity, rover to Gale Crater on Mars on August 6, 2012 UTC, the rover transmitted an X-band signal composed of carrier and tone frequencies and a UHF signal modulated with an 8kbps data stream. During EDL, the spacecraft's orientation is determined by its guidance and mechanical subsystems to ensure that the vehicle land safely at its destination. Although orientation to maximize telecom performance is not possible, antennas are especially designed and mounted to provide the best possible line of sight to Earth and to the Mars orbiters supporting MSL's landing. The tones and data transmitted over these links are selected carefully to reflect the most essential parameters of the vehicle's state and the performance of the EDL subsystems for post-EDL reconstruction should no further data transmission from the vehicle be possible. This paper addresses the configuration of the X band receive system used at NASA / JPL's Deep Space Network (DSN) to capture the signal spectrum of MSL's X band carrier and tone signal, examines the MSL vehicle state information obtained from the X band carrier signal only and contrasts the Doppler-derived information against the post-EDL known vehicle state. The paper begins with a description of the MSL EDL sequence of events and discusses the impact of the EDL maneuvers such as guided entry, parachute deploy, and powered descent on the frequency observables expected at the DSN. The range of Doppler dynamics possible is derived from extensive 6 Degrees-Of-Freedom (6 DOF) vehicle state calculations performed by MSL's EDL simulation team. The configuration of the DSN's receive system, using the Radio Science Receivers (RSR) to perform open-loop recording for both for nominal and off-nominal EDL scenarios, is detailed. Expected signal carrier power-to-noise levels during EDL are shown and their impact on signal detection is considered. Particular

  14. Sleuthing the MSL EDL performance from an X band carrier perspective

    Science.gov (United States)

    Oudrhiri, Kamal; Asmar, Sami; Estabrook, Polly; Kahan, Daniel; Mukai, Ryan; Ilott, Peter; Schratz, Brian; Soriano, Melissa; Finley, Susan; Shidner, Jeremy

    During the Entry, Descent, and Landing (EDL) of NASA's Mars Science Laboratory (MSL), or Curiosity, rover to Gale Crater on Mars on August 6, 2012 UTC, the rover transmitted an X-band signal composed of carrier and tone frequencies and a UHF signal modulated with an 8kbps data stream. During EDL, the spacecraft's orientation is determined by its guidance and mechanical subsystems to ensure that the vehicle land safely at its destination. Although orientation to maximize telecom performance is not possible, antennas are especially designed and mounted to provide the best possible line of sight to Earth and to the Mars orbiters supporting MSL's landing. The tones and data transmitted over these links are selected carefully to reflect the most essential parameters of the vehicle's state and the performance of the EDL subsystems for post-EDL reconstruction should no further data transmission from the vehicle be possible. This paper addresses the configuration of the X band receive system used at NASA / JPL's Deep Space Network (DSN) to capture the signal spectrum of MSL's X band carrier and tone signal, examines the MSL vehicle state information obtained from the X band carrier signal only and contrasts the Doppler-derived information against the post-EDL known vehicle state. The paper begins with a description of the MSL EDL sequence of events and discusses the impact of the EDL maneuvers such as guided entry, parachute deploy, and powered descent on the frequency observables expected at the DSN. The range of Doppler dynamics possible is derived from extensive 6 Degrees-Of-Freedom (6 DOF) vehicle state calculations performed by MSL's EDL simulation team. The configuration of the DSN's receive system, using the Radio Science Receivers (RSR) to perform open-loop recording for both for nominal and off-nominal EDL scenarios, is detailed. Expected signal carrier power-to-noise levels during EDL are shown and their impact on signal detection is considered. Particula

  15. Testing a new multivariate GNSS carrier phase attitude determination method for remote sensing platforms

    Science.gov (United States)

    Giorgi, Gabriele; Teunissen, Peter J. G.; Verhagen, Sandra; Buist, Peter J.

    2010-07-01

    GNSS (Global Navigation Satellite Systems)-based attitude determination is an important field of study, since it is a valuable technique for the orientation estimation of remote sensing platforms. To achieve highly accurate angular estimates, the precise GNSS carrier phase observables must be employed. However, in order to take full advantage of the high precision, the unknown integer ambiguities of the carrier phase observables need to be resolved. This contribution presents a GNSS carrier phase-based attitude determination method that determines the integer ambiguities and attitude in an integral manner, thereby fully exploiting the known body geometry of the multi-antennae configuration. It is shown that this integral approach aids the ambiguity resolution process tremendously and strongly improves the capacity of fixing the correct set of integer ambiguities. In this contribution, the challenging scenario of single-epoch, single-frequency attitude determination is addressed. This guarantees a total independence from carrier phase slips and losses of lock, and it also does not require any a priori motion model for the platform. The method presented is a multivariate constrained version of the popular LAMBDA method and it is tested on data collected during an airborne remote sensing campaign.

  16. Meiotic recombination, synapsis, meiotic inactivation and sperm aneuploidy in a chromosome 1 inversion carrier.

    Science.gov (United States)

    Kirkpatrick, Gordon; Chow, Victor; Ma, Sai

    2012-01-01

    Disrupted meiotic behaviour of inversion carriers may be responsible for suboptimal sperm parameters in these carriers. This study investigated meiotic recombination, synapsis, transcriptional silencing and chromosome segregation effects in a pericentric inv(1) carrier. Recombination (MLH1), synapsis (SYCP1, SYCP3) and transcriptional inactivation (γH2AX, BRCA1) were examined by fluorescence immunostaining. Chromosome specific rates of recombination were determined by fluorescence in-situ hybridization. Furthermore, testicular sperm was examined for aneuploidy and segregation of the inv(1). Our findings showed that global recombination rates were similar to controls. Recombination on the inv(1) and the sex chromosomes were reduced. The inv(1) associated with the XY body in 43.4% of cells, in which XY recombination was disproportionately absent, and 94.3% of cells displayed asynapsed regions which displayed meiotic silencing regardless of their association with the XY body. Furthermore, a low frequency of chromosomal imbalance was observed in spermatozoa (3.4%). Our results suggest that certain inversion carriers may display unimpaired global recombination and impaired recombination on the involved and the sex chromosomes during meiosis. Asynapsis or inversion-loop formation in the inverted region may be responsible for impaired spermatogenesis and may prevent sperm-chromosome imbalance.

  17. Loss of heterozygosity and carrier identification in Duchenne muscular dystrophy: a familiar case with recombination event

    Directory of Open Access Journals (Sweden)

    Fonseca-Mendoza Dora Janeth

    2012-04-01

    Full Text Available Duchenne/Becker Muscular Dystrophy (DMD/BMD is an X-linked recessive disease characterizedby muscular weakness. It is caused by mutations on the dystrophin gen. Loss of heterozygosityallows us to identify female carriers of deletions on the dystrophin gen. Objective: identifyfemale carriers in a family with a patient affected by DMD. Material and methods: nine familymembers and the affected child were analyzed using DNA extraction and posterior amplificationof ten STRs on the dystrophin gen. Haplotypes were constructed and the carrier status determinedin two of the six women analyzed due to loss of heterozygosity in three STRs. Additionally, weobserved a recombination event. Conclusions: loss of heterozygosity allows us to establish witha certainty of 100% the carrier status of females with deletions on the dystrophin gen. By theconstruction of haplotypes we were able to identify the X chromosome with the deletion in twoof the six women analyzed. We also determined a recombination event in one of the sisters of theaffected child. These are described with a high frequency (12%. A possible origin for the mutationis a gonadal mosaicism in the maternal grandfather or in the mother of the affected childin a very early stage in embryogensis. This can be concluded using the analysis of haplotypes.

  18. Global Carrier Rates of Rare Inherited Disorders Using Population Exome Sequences.

    Directory of Open Access Journals (Sweden)

    Kohei Fujikura

    Full Text Available Exome sequencing has revealed the causative mutations behind numerous rare, inherited disorders, but it is challenging to find reliable epidemiological values for rare disorders. Here, I provide a genetic epidemiology method to identify the causative mutations behind rare, inherited disorders using two population exome sequences (1000 Genomes and NHLBI. I created global maps of carrier rate distribution for 18 recessive disorders in 16 diverse ethnic populations. Out of a total of 161 mutations associated with 18 recessive disorders, I detected 24 mutations in either or both exome studies. The genetic mapping revealed strong international spatial heterogeneities in the carrier patterns of the inherited disorders. I next validated this methodology by statistically evaluating the carrier rate of one well-understood disorder, sickle cell anemia (SCA. The population exome-based epidemiology of SCA [African (allele frequency (AF = 0.0454, N = 2447, Asian (AF = 0, N = 286, European (AF = 0.000214, N = 4677, and Hispanic (AF = 0.0111, N = 362] was not significantly different from that obtained from a clinical prevalence survey. A pair-wise proportion test revealed no significant differences between the two exome projects in terms of AF (46/48 cases; P > 0.05. I conclude that population exome-based carrier rates can form the foundation for a prospectively maintained database of use to clinical geneticists. Similar modeling methods can be applied to many inherited disorders.

  19. Joint sub-carrier pairing and resource allocation for cognitive networks with adaptive relaying

    KAUST Repository

    Soury, Hamza

    2013-11-09

    Relayed transmission in a cognitive radio (CR) environment could be used to increase the coverage and capacity of communication system that benefits already from the efficient management of the spectrum developed by CR. Furthermore, there are many types of cooperative communications, including decode-and-forward (DAF) and amplify-and-forward (AAF). In this paper, these techniques are combined in an adaptive mode to benefit from its forwarding advantages; this mode is called adaptive relaying protocol (ARP). Moreover, this work focuses on the joint power allocation in a cognitive radio system in a cooperative mode that operates ARP in multi-carrier mode. The multi-carrier scenario is used in an orthogonal frequency division multiplexing (OFDM) mode, and the problem is formulated to maximize the end-to-end rate by searching the best power allocation at the transmitters. This work includes, besides the ARP model, a sub-carrier pairing strategy that allows the relays to switch to the best sub-carrier pairs to increase the throughput. The optimization problem is formulated and solved under the interference and power budget constraints using the sub-gradient algorithm. The simulation results confirm the efficiency of the proposed adaptive relaying protocol in comparison to other relaying techniques. The results show also the consequence of the choice of the pairing strategy. 2013 Stolojescu-Crisan and Isar; licensee Springer.

  20. SOLID LIPID NANOPARTICLES AND NANO LIPID CARRIERS: AS NOVEL SOLID LIPID BASED DRUG CARRIER

    Directory of Open Access Journals (Sweden)

    Girish B. Singhal

    2011-02-01

    Full Text Available Interest in lipid based drug delivery has developed over the past decade fuelled by a better understanding of the multiple roles lipids may play in enhancing oral bioavailability. Moreover, the emergence of novel excipients with acceptable regulatory and safety profiles coupled with advances in formulation technologies have greatly improved the potential for successful lipid based formulations. Solid lipid nanoparticles (SLN introduced in 1991 represent an alternative carrier system to traditional colloidal carriers, such as emulsions, liposomes and polymeric micro- and nanoparticles. SLN combine advantages of the traditional systems but avoid some of their major disadvantages. This paper reviews the present state of the art regarding production techniques for SLN/ nanostructured lipid carrier (NLC, drug incorporation method and types, stability. The potential of SLN/NLC to be exploited for the different administration routes is also highlighted.

  1. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Science.gov (United States)

    Meisel, K. D.; Pasveer, W. F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P. A.; Blom, P. W. M.; de Leeuw, D. M.; Michels, M. A. J.

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices.

  2. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  3. Carriers of equine infectious anemia virus.

    Science.gov (United States)

    Coggins, L

    1984-02-01

    Presently available data continue to support the idea that once a horse is infected with equine infectious anemia virus it remains infected indefinitely. Infection may not always be demonstrated by inoculation of plasma, serum, or whole blood transfusions into susceptible recipients, but transfusions of fresh whole blood will be infective in at least 95% of the horses testing positive in the agar gel immunodiffusion test. For detection of infectivity in a small percentage of inapparent carriers, it appears necessary to inoculate washed leukocytes collected over a period of time.

  4. Carbon-neutral fuels and energy carriers

    CERN Document Server

    Muradov, Nazim Z

    2011-01-01

    Concerns over an unstable energy supply and the adverse environmental impact of carbonaceous fuels have triggered considerable efforts worldwide to find carbon-free or low-carbon alternatives to conventional fossil fuels. Carbon-Neutral Fuels and Energy Carriers emphasizes the vital role of carbon-neutral energy sources, transportation fuels, and associated technologies for establishing a sustainable energy future. Each chapter draws on the insight of world-renowned experts in such diverse fields as photochemistry and electrochemistry, solar and nuclear energy, biofuels and synthetic fuels, ca

  5. Hardware Trojan by Hot Carrier Injection

    CERN Document Server

    Shiyanovskii, Y; Papachristou, C; Weyer, D; Clay, W

    2009-01-01

    This paper discusses how hot carrier injection (HCI) can be exploited to create a trojan that will cause hardware failures. The trojan is produced not via additional logic circuitry but by controlled scenarios that maximize and accelerate the HCI effect in transistors. These scenarios range from manipulating the manufacturing process to varying the internal voltage distribution. This new type of trojan is difficult to test due to its gradual hardware degradation mechanism. This paper describes the HCI effect, detection techniques and discusses the possibility for maliciously induced HCI trojans.

  6. The solute carrier 6 family of transporters

    DEFF Research Database (Denmark)

    Bröer, Stefan; Gether, Ulrik

    2012-01-01

    The solute carrier 6 (SLC6) family of the human genome comprises transporters for neurotransmitters, amino acids, osmolytes and energy metabolites. Members of this family play critical roles in neurotransmission, cellular and whole body homeostasis. Malfunction or altered expression...... of these transporters is associated with a variety of diseases. Pharmacological inhibition of the neurotransmitter transporters in this family is an important strategy in the management of neurological and psychiatric disorders. This review provides an overview of the biochemical and pharmacological properties...... of the SLC6 family transporters....

  7. Spatial Frequency Scheduling for Uplink SC-FDMA based Linearly Precoded LTE Multiuser MIMO Systems

    DEFF Research Database (Denmark)

    Lin, Zihuai; Xiao, Pei; Sørensen, Troels Bundgaard;

    2010-01-01

    This paper investigates the performance of the 3GPP Long Term Evolution (LTE) uplink Single Carrier (SC) Frequency Division Multiple Access (FDMA) based linearly precoded multiuserMultiple InputMultiple Output (MIMO) systems with frequency domain packet scheduling. A mathematical expression...

  8. 78 FR 5243 - Motor Carrier Safety Advisory Committee (MCSAC): Public Meeting of Subcommittees

    Science.gov (United States)

    2013-01-24

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee (MCSAC): Public Meeting of Subcommittees AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of meeting of Motor Carrier Safety Advisory Committee (MCSAC). SUMMARY: FMCSA announces that...

  9. 76 FR 62496 - Motor Carrier Safety Advisory Committee Series of Public Subcommittee Meetings

    Science.gov (United States)

    2011-10-07

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee Series of Public Subcommittee Meetings AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of meeting. SUMMARY: The FMCSA's Motor Carrier Safety Advisory Committee (MCSAC) will hold working group...

  10. 76 FR 5424 - Motor Carrier Safety Advisory Committee; Request for Nominations

    Science.gov (United States)

    2011-01-31

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee; Request for Nominations AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Request for Nominations to the Motor Carrier Safety Advisory Committee (MCSAC). SUMMARY: The FMCSA solicits nominations...

  11. 77 FR 60507 - Motor Carrier Safety Advisory Committee (MCSAC): Public Subcommittee Meeting

    Science.gov (United States)

    2012-10-03

    ... Federal Motor Carrier Safety Administration Motor Carrier Safety Advisory Committee (MCSAC): Public Subcommittee Meeting AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice of Meeting of Compliance, Safety, Accountability (CSA) Subcommittee of Motor Carrier Safety...

  12. Frequency selectivity at very low centre frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Marquardt, Torsten

    2010-01-01

    A significant factor in the decrease of sensitivity to low-frequency sound is the helicotrema shunt effect. In humans, it causes a slope increase of the middle-ear transfer function (METF) from 6 dB/oct to 12 dB/oct below approximately 50 Hz [Marquardt et al., J.Acoust. Soc. Am. 121, 3628......-3638 (2007)]. Recent experiments showed that the exact frequency varies from individual to individual. Besides, the helicotrema region in the METF has been found to highly influence frequency selectivity for centre frequencies (CFs) below 80 Hz (Jurado and Moore in prep). By using individual METF...... in the shape of the METFs, thought to be affected by the helicotrema impedance. Preliminary analysis indicates that individual differences in the METFs might underlay the observed individual differences in frequency selectivity. Main effects predicted by the calculations are a pronounced flattening off...

  13. Bayesian integer frequency offset estimator for MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Carrier frequency offset (CFO) in MIMO-OFDM systems can be decoupled into two parts: fraction frequency offset (FFO) and integer frequency offset (IFO). The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.

  14. Center of Mass Estimation for a Spinning Spacecraft Using Doppler Shift of the GPS Carrier Frequency

    Science.gov (United States)

    Sedlak, Joseph E.

    2016-01-01

    A sequential filter is presented for estimating the center of mass (CM) of a spinning spacecraft using Doppler shift data from a set of onboard Global Positioning System (GPS) receivers. The advantage of the proposed method is that it is passive and can be run continuously in the background without using commanded thruster firings to excite spacecraft dynamical motion for observability. The NASA Magnetospheric Multiscale (MMS) mission is used as a test case for the CM estimator. The four MMS spacecraft carry star cameras for accurate attitude and spin rate estimation. The angle between the spacecraft nominal spin axis (for MMS this is the geometric body Z-axis) and the major principal axis of inertia is called the coning angle. The transverse components of the estimated rate provide a direct measure of the coning angle. The coning angle has been seen to shift slightly after every orbit and attitude maneuver. This change is attributed to a small asymmetry in the fuel distribution that changes with each burn. This paper shows a correlation between the apparent mass asymmetry deduced from the variations in the coning angle and the CM estimates made using the GPS Doppler data. The consistency between the changes in the coning angle and the CM provides validation of the proposed GPS Doppler method for estimation of the CM on spinning spacecraft.

  15. High-Frequency Link Inverter for Fuel CellsBased on Multiple-Carrier PWM

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A similar circuit as Fig. 12 can be realized with MOSFET or IGBT devices configured as bi-directional pairs in the output bridge. In this case, the complete process in Fig. 8 would be needed to generate the complete 50% gate drive pulses. The 50% gate pulses still support pulse transformer coupling, retaining the simplicity of the gate drive isolation. The PWM cycloconverter process scales directly to higher switching speeds possible with these devices.

  16. Combating Impairments in Multi-carrier Systems: A Compressed Sensing Approach

    KAUST Repository

    Al-Shuhail, Shamael

    2015-05-01

    Multi-carrier systems suffer from several impairments, and communication system engineers use powerful signal processing tools to combat these impairments and keep up with the capacity/rate demands. Compressed sensing (CS) is one such tool that allows recovering any sparse signal, requiring only a few measurements in a domain that is incoherent with the domain of sparsity. Almost all signals of interest have some degree of sparsity, and in this work we utilize the sparsity of impairments in orthogonal frequency division multiplexing (OFDM) and its variants (i.e., orthogonal frequency division multiplexing access (OFDMA) and single-carrier frequency-division multiple access (SC-FDMA)) to combat them using CS. We start with the problem of peak-to-average power ratio (PAPR) reduction in OFDM. OFDM signals suffer from high PAPR and clipping is the simplest PAPR reduction scheme. However, clipping introduces inband distortions that result in compromised performance and hence needs to be mitigated at the receiver. Due to the high PAPR nature of the OFDM signal, only a few instances are clipped, these clipping distortions can be recovered at the receiver by employing CS. We then extend the proposed clipping recovery scheme to an interleaved OFDMA system. Interleaved OFDMA presents a special structure that result in only self-inflicted clipping distortions. In this work, we prove that distortions do not spread over multiple users (while utilizing interleaved carrier assignment in OFDMA) and construct a CS system that recovers the clipping distortions on each user. Finally, we address the problem of narrowband interference (NBI) in SC-FDMA. Unlike OFDM and OFDMA systems, SC-FDMA does not suffer from high PAPR, but (as the data is encoded in time domain) is seriously vulnerable to information loss owing to NBI. Utilizing the sparse nature of NBI (in frequency domain) we combat its effect on SC-FDMA system by CS recovery.

  17. Mutation spectrum of beta-thalassemia among carriers in Birjand and Amirabad village

    Directory of Open Access Journals (Sweden)

    Nasrin Zandi Dashtebayaz

    2016-04-01

    Full Text Available Background and Aim: Thalassemia is considered as the most important monogenic disorders around the world. So far, about 60 mutations of this type have been reported in Iranian patients. Comparison between different provinces of the country reveals that the dispersion of the mutations is significantly various with respect to their types and frequencies. The current study aimed at assessing prevalent molecular mutations in β Thalassemia carriers in Birjand  and Amirabad at the suburb of the city. Materials and Methods: In this descriptive in-vitro study, 34 carriers (15 females and 19 males, who had been identified through marriage screening tests at the health centers in the South Khorasan province were assessed. After obtaining written informed consent of the subjects and completing the respective questionnaires, 2 cc of intravenous blood sample from each subject were collected into EDTA tubes. Salting out and Arms-PCR methods were used for DNA extraction and mutation detection, respectively. Finally, the obtained data was analysed by means of SPSS software (V;19 using Fisher’s test at the significant level of P<0.05. Results: It was found that among five mutations on 68 chromosomes,  IVS 1-5 mutation with 47.1% frequency was the highest; and the mutations of Codon, Fr 8/9 , IVS II-1 5 , and Codon 37/38/39 had the frequency of 17.6%, 8.8%, 5.9% ,and 5.9% respectively. Out of the mutations, 14.7 % .remained undetermined. Conclusion: The mutation patterns obtained in Birjand reveal an outstanding difference with the state of affairs in the north and west of IRAN..High frequency of consanguity marriages between thalassemia carrier individuals indicates the potential reason behind increasing the number of patients with major thalassemia.

  18. Theory of Carrier Phase Ambiguity Resolution

    Institute of Scientific and Technical Information of China (English)

    P. J. G. Teunissen

    2003-01-01

    Carrier phase ambiguity resolution is the key to high precision Global Navigation Satellite System(GNSS) positioning and navigation. It applies to a great variety of current and future models of GPS, modernized GPS and Galileo. A proper handling of carrier phase ambiguity resolution requires a proper understanding of the underlying theory of integer inference. In this contribution a brief review is given of the probabilistic theory of integer ambiguity estimation. We describe the concept of ambiguity pull-in regions, introduce the class of admissible integer estimators, determine their probability mass functions and show how their variability solution. The theory is worked out in more detail for integer least-squares and integer bootstrapping. It is shown that the integer least-squares principle maximizes the probability of correct integer estimation. Sharp and easy-to-compute bounds are given for both the ambiguity success rate and the baseline's probability of concentration. Finally the probability density function of the ambiguity residuals is determined. This allows one for the first time to formulate rigorous tests for the integerness of the parameters.

  19. Facilitated transport near the carrier saturation limit

    Directory of Open Access Journals (Sweden)

    Anawat Sungpet

    2002-11-01

    Full Text Available Permeation of ethylbenzene, styrene and 1-hexene through perfluorosulfonate ionomer membranes was carried out with the feed concentrations ranging from 1 M to pure. On comparison, fluxes of ethylbenzene through the Ag+-form membrane were the lowest. Only a small increase in ethylbenzene flux was observed after the feed concentration exceeded 3 M, indicating the existence of carrier saturation. The increase in styrene flux was suppressed to some degree at high concentration driving forces. In contrast, 1-hexene flux was the highest and continued to increase even at very high feed concentrations. After the experiments with pure feeds, extraction of the solutes from the membranes revealed that 62.5% of Ag+ ions reacted with 1-hexene as against 40.6% for styrene and 28.9% for ethylbenzene. Equilibrium constants, determined by distribution method, of 1-hexene, styrene and ethylbenzene were 129, 2.2 and 0.7 M-1 respectively, which suggested that stability of the complex was a key factor in the carrier saturation phenomenon.

  20. Localized charge carriers in graphene nanodevices

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, D., E-mail: dominikb@phys.ethz.ch; Varlet, A.; Simonet, P.; Eich, M.; Overweg, H. C.; Ihn, T.; Ensslin, K. [Solid State Physics Laboratory, ETH Zurich, 8093 Zurich (Switzerland)

    2015-09-15

    Graphene—two-dimensional carbon—is a material with unique mechanical, optical, chemical, and electronic properties. Its use in a wide range of applications was therefore suggested. From an electronic point of view, nanostructured graphene is of great interest due to the potential opening of a band gap, applications in quantum devices, and investigations of physical phenomena. Narrow graphene stripes called “nanoribbons” show clearly different electronical transport properties than micron-sized graphene devices. The conductivity is generally reduced and around the charge neutrality point, the conductance is nearly completely suppressed. While various mechanisms can lead to this observed suppression of conductance, disordered edges resulting in localized charge carriers are likely the main cause in a large number of experiments. Localized charge carriers manifest themselves in transport experiments by the appearance of Coulomb blockade diamonds. This review focuses on the mechanisms responsible for this charge localization, on interpreting the transport details, and on discussing the consequences for physics and applications. Effects such as multiple coupled sites of localized charge, cotunneling processes, and excited states are discussed. Also, different geometries of quantum devices are compared. Finally, an outlook is provided, where open questions are addressed.

  1. The effect of carrier surface and bulk properties on drug particle detachment from crystalline lactose carrier particles during inhalation, as function of carrier payload and mixing time

    NARCIS (Netherlands)

    Dickhoff, B.H.J.; de Boer, Anne; Lambregts, D.; Frijlink, H.W.

    2003-01-01

    The effect of carrier payload and mixing time on the redispersion of drug particles from adhesive mixtures during inhalation for two different drugs (budesonide and disodium cromoglycate) has been investigated. A special test inhaler which retains carrier crystals during inhalation was used at 30 an

  2. Graphene, a material for high temperature devices; intrinsic carrier density, carrier drift velocity, and lattice energy

    CERN Document Server

    Yin, Yan; Wang, Li; Jin, Kuijuan; Wang, Wenzhong

    2016-01-01

    Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of ...

  3. High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films

    NARCIS (Netherlands)

    Suchand Sandeep, C.S.; Ten Cate, S.; Schins, J.M.; Savenije, T.J.; Liu, Y.; Law, M.; Kinge, S.; Houtepen, A.J.; Siebbeles, L.D.A.

    2013-01-01

    Carrier multiplication, the generation of multiple electron–hole pairs by a single photon, is of great interest for solar cells as it may enhance their photocurrent. This process has been shown to occur efficiently in colloidal quantum dots, however, harvesting of the generated multiple charges has

  4. Carriers of 21-hydroxylase deficiency are not at increased risk for hyperandrogenism.

    Science.gov (United States)

    Knochenhauer, E S; Cortet-Rudelli, C; Cunnigham, R D; Conway-Myers, B A; Dewailly, D; Azziz, R

    1997-02-01

    gene conversion. All 38 carriers were examined for historical and physical features of hyperandrogenism. Hirsutism was defined as a Ferriman-Gallwey score of 6 or more, menstrual/ovulatory dysfunction as a history of menstrual cycles of more than 35-day, and hyperandrogenemia as total or free T, A4, and/or dehydroepiandrosterone sulfate levels above the upper 95th percentile of control values. Further, defining functional androgen excess (FAE) as the presence of at least 2 of the 3 hyperandrogenic features, 4 of 38 (10.5%) of carriers appeared to be affected (95% confidence interval, 2.9-24.8%). Assuming an expected prevalence rate of FAE in the general population of 5-20%, the frequency of FAE among our carriers was not significantly higher than expected. In conclusion, heterozygosity for CYP21 mutations does not appear to increase the risk of clinically evident hyperandrogenism, although carrying the defect was associated with higher mean and free T levels. Finally, due to the low frequency of androgen excess in our heterozygote population, we were unable to correlate the severity of the CYP21 mutation and/or the 17-OHP response to ACTH stimulation with the presence of the phenotype.

  5. Charge transfer polarisation wave and carrier pairing in the high T(sub c) copper oxides

    Science.gov (United States)

    Chakraverty, B. K.

    1990-01-01

    The High T(sub c) oxides are highly polarizable materials and are charge transfer insulators. The charge transfer polarization wave formalism is developed in these oxides. The dispersion relationships due to long range dipole-dipole interaction of a charge transfer dipole lattice are obtained in 3-D and 2-D. These are high frequency bosons and their coupling with carriers is weak and antiadiabatic in nature. As a result, the mass renormalization of the carriers is negligible in complete contrast to conventional electron-phonon interaction, that give polarons and bipolarons. Both bound and superconducting pairing is discussed for a model Hamiltonian valid in the antiadiabatic regime, both in 3-D and 2-D. The stability of the charge transfer dipole lattice has interesting consequences that are discussed.

  6. Handover Performance over a Coordinated Contiguous Carrier Aggregation Deployment Scenario in the LTE-Advanced System

    Directory of Open Access Journals (Sweden)

    Ibraheem Shayea

    2014-01-01

    Full Text Available Although various carrier aggregation deployment scenarios (CADSs have been introduced in the LTE-Advanced system, issues related to insufficient eNB coverage that leads to low throughput and high drop call have yet to be solved. This paper proposes a new deployment scenario called coordinated contiguous-CADS (CC-CADS, which utilizes two-component carriers (CCs that operate on two frequencies located in a contiguous band. Each CC antenna is directed to a cell boundary of the other CC. The handover performance of users with various mobility speeds under CC-CADS has been investigated and compared with various deployment scenarios proposed by 3GPP. Simulation results show that the received signal reference power (RSRP enhancement and performed handover, ping-pong, drop call, and outage probabilities reductions in CC-CADS outperformed the 3GPP’s CADSs, thus leading to reduced interruption time, improved spectral efficiency, and seamless handover.

  7. Acoustic manipulation of active spherical carriers: Generation of negative radiation force

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Majid, E-mail: majid_rajabi@iust.ac.ir; Mojahed, Alireza

    2016-09-15

    This paper examines theoretically a novel mechanism of generating negative (pulling) radiation force for acoustic manipulation of spherical carriers equipped with piezoelectric actuators in its inner surface. In this mechanism, the spherical particle is handled by common plane progressive monochromatic acoustic waves instead of zero-/higher- order Bessel beams or standing waves field. The handling strategy is based on applying a spatially uniform harmonic electrical voltage at the piezoelectric actuator with the same frequency of handling acoustic waves, in order to change the radiation force effect from repulsive (away from source) to attractive (toward source). This study may be considered as a start point for development of contact-free precise handling and entrapment technology of active carriers which are essential in many engineering and medicine applications.

  8. Acoustic manipulation of active spherical carriers: Generation of negative radiation force

    Science.gov (United States)

    Rajabi, Majid; Mojahed, Alireza

    2016-09-01

    This paper examines theoretically a novel mechanism of generating negative (pulling) radiation force for acoustic manipulation of spherical carriers equipped with piezoelectric actuators in its inner surface. In this mechanism, the spherical particle is handled by common plane progressive monochromatic acoustic waves instead of zero-/higher- order Bessel beams or standing waves field. The handling strategy is based on applying a spatially uniform harmonic electrical voltage at the piezoelectric actuator with the same frequency of handling acoustic waves, in order to change the radiation force effect from repulsive (away from source) to attractive (toward source). This study may be considered as a start point for development of contact-free precise handling and entrapment technology of active carriers which are essential in many engineering and medicine applications.

  9. Carrier-carrier scattering in the gain dynamics of InxGa1-xAs/AlyGa1-yAs diode lasers

    DEFF Research Database (Denmark)

    Sanders, Gary D; Sun, C.-K.; Golubovic, B.

    1996-01-01

    for the carrier distributions using an adaptive Runge-Kutta routine. This procedure is less computationally intensive than a full Monte Carlo simulation. The results show that the inclusion of carrier-carrier scattering improves previous results where only carrier-phonon scattering was included and that carrier...

  10. High integrity carrier phase navigation using multiple civil GPS signals

    Science.gov (United States)

    Jung, Jaewoo

    2000-11-01

    A navigation system should guide users to their destinations accurately and reliably. Among the many available navigation aids, the Global Positioning System stands out due to its unique capabilities. It is a satellite-based navigation system which covers the entire Earth with horizontal accuracy of 20 meters for stand alone civil users. Today, the GPS provides only one civil signal, but two more signals will be available in the near future. GPS will provide a second signal at 1227.60 MHz (L2) and a third signal at 1176.45 MHz (Lc), in addition to the current signal at 1575.42 MHz (L1). The focus of this thesis is exploring the possibility of using beat frequencies of these signals to provide navigation aid to users with high accuracy and integrity. To achieve high accuracy, the carrier phase differential GPS is used. The integer ambiguity is resolved using the Cascade Integer Resolution (CIR), which is defined in this thesis. The CIR is an instantaneous, geometry-free integer resolution method utilizing beat frequencies of GPS signals. To insure high integrity, the probability of incorrect integer ambiguity resolution using the CIR is analyzed. The CIR can immediately resolve the Lc integer ambiguity up to 2.4 km from the reference receiver, the Widelane (L1-L2) integer ambiguity up to 22 km, and the Extra Widelane (L2-Lc) integer ambiguity from there on, with probability of incorrect integer resolution of 10-4 . The optimal use of algebraic combinations of multiple GPS signals are also investigated in this thesis. Finally, the gradient of residual differential ionospheric error is estimated to stimated to increase performance of the CIR.

  11. Novel recruitment strategy to enrich for LRRK2 mutation carriers.

    Science.gov (United States)

    Foroud, Tatiana; Smith, Danielle; Jackson, Jacqueline; Verbrugge, Jennifer; Halter, Cheryl; Wetherill, Leah; Sims, Katherine; Xin, Winnie; Arnedo, Vanessa; Lasch, Shirley; Marek, Kenneth

    2015-09-01

    The LRRK2 G2019S mutation is found at higher frequency among Parkinson disease (PD) patients of Ashkenazi Jewish (AJ) ancestry. This study was designed to test whether an internet-based approach could be an effective approach to screen and identify mutation carriers. Individuals with and without PD of AJ ancestry were recruited and consented through an internet-based study website. An algorithm was applied to a series of screening questions to identify individuals at increased risk to carry the LRRK2 G2019S mutation. About 1000 individuals completed the initial screening. Around 741 qualified for mutation testing and 650 were tested. Seventy-two individuals carried at least one LRRK2 G2019S mutation; 38 with PD (12.5%) and 34 without (10.1%). Among the AJ PD participants, each affected first-degree relative increased the likelihood the individual was LRRK2+ [OR = 4.7; 95% confidence interval = (2.4-9.0)]. The same was not observed among the unaffected AJ subjects (P = 0.11). An internet-based approach successfully screened large numbers of individuals to identify those with risk factors increasing the likelihood that they carried a LRRK2 G2019S mutation. A similar approach could be implemented in other disorders to identify individuals for clinical trials, biomarker analyses and other types of research studies.

  12. Optical carrier-based microwave interferometers for sensing application

    Science.gov (United States)

    Huang, Jie; Lan, Xinwei; Wang, Hanzheng; Yuan, Lei; Xiao, Hai

    2014-06-01

    Optical fiber interferometers (OFIs) have been extensively utilized for precise measurements of various physical/chemical quantities (e.g., temperature, strain, pressure, rotation, refractive index, etc.). However, the random change of polarization states along the optical fibers and the strong dependence on the materials and geometries of the optical waveguides are problematic for acquiring high quality interference signal. Meanwhile, difficulty in multiplexing has always been a bottleneck on the application scopes of OFIs. Here, we present a sensing concept of optical carrier based microwave interferometry (OCMI) by reading optical interferometric sensors in microwave domain. It combines the advantages from both optics and microwave. The low oscillation frequency of the microwave can hardly distinguish the optical differences from both modal and polarization dispersion making it insensitive to the optical waveguides/materials. The phase information of the microwave can be unambiguitly resolved so that it has potential in fully distributed sensing. The OCMI concept has been implemented in different types of interferometers (i.e., Michelson, Mach-Zehnder, Fabry-Perot) among different optical waveguides (i.e., singlemode, multimode, and sapphire fibers) with excellent signal-to-noise ratio (SNR) and low polarization dependence. A spatially continuous distributed strain sensing has been demonstrated.

  13. Charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene): Effects of carrier bimolecular recombination and trapping

    Science.gov (United States)

    Soci, Cesare; Moses, Daniel; Xu, Qing-Hua; Heeger, Alan J.

    2005-12-01

    We have studied the charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene) over a broad time range using fast (t>100ps) transient photoconductivity measurements. The carrier density was also monitored (t>100fs) by means of photoinduced absorption probed at the infrared active vibrational modes. We find that promptly upon charge-carrier photogeneration, the initial polaron dynamics is governed by bimolecular recombination, while later in the subnanosecond time regime carrier trapping gives rise to an exponential decay of the photocurrent. The more sensitive transient photocurrent measurements indicate that in the low excitation regime, when the density of photocarriers is comparable to that of the trapping states (˜1016cm-3) , carrier hopping between traps along with transport via extended states determines the carrier relaxation, a mechanism that is manifested by a long-lived photocurrent “tail.” This photocurrent tail is reduced by lowering the temperature and/or by increasing the excitation density. Based on these data, we develop a comprehensive kinetic model that takes into account the bipolar charge transport, the free-carrier bimolecular recombination, the carrier trapping, and the carrier recombination involving free and trapped carriers.

  14. Characteristics of participants in a gestational carrier program.

    Science.gov (United States)

    Braverman, A M; Corson, S L

    1992-08-01

    Genetic parents and gestational carriers in our gestational carrier program were evaluated by psychodiagnostic interview and by the Minnesota Multiphasic Personality Interview-2 (MMPI-2), a widely used objective psychological test, to identify psychopathology and describe personality characteristics. Overall, participants exhibited no overt psychopathology. Personality differences were found between gestational carriers and genetic mothers and genetic fathers and mothers. Clinical interviews revealed that gestational carriers tended to be the dominant partner in the relationship, were motivated by a wish to help an infertile couple, enjoyed being pregnant, showed narcissistic needs, and expressed a wish for secondary financial gain. The majority of gestational carriers stated that they had considered becoming a traditional surrogate but felt they could not surrender a child that was genetically theirs. These results indicate that there is not any predisposing psychopathology which attracts participants to the gestational carrier program.

  15. Graphene radio frequency receiver integrated circuit.

    Science.gov (United States)

    Han, Shu-Jen; Garcia, Alberto Valdes; Oida, Satoshi; Jenkins, Keith A; Haensch, Wilfried

    2014-01-01

    Graphene has attracted much interest as a future channel material in radio frequency electronics because of its superior electrical properties. Fabrication of a graphene integrated circuit without significantly degrading transistor performance has proven to be challenging, posing one of the major bottlenecks to compete with existing technologies. Here we present a fabrication method fully preserving graphene transistor quality, demonstrated with the implementation of a high-performance three-stage graphene integrated circuit. The circuit operates as a radio frequency receiver performing signal amplification, filtering and downconversion mixing. All circuit components are integrated into 0.6 mm(2) area and fabricated on 200 mm silicon wafers, showing the unprecedented graphene circuit complexity and silicon complementary metal-oxide-semiconductor process compatibility. The demonstrated circuit performance allow us to use graphene integrated circuit to perform practical wireless communication functions, receiving and restoring digital text transmitted on a 4.3-GHz carrier signal.

  16. Improvement of GNSS Carrier Phase Accuracy Using MEMS Accelerometer-Aided Phase-Locked Loops for Earthquake Monitoring

    Directory of Open Access Journals (Sweden)

    Tisheng Zhang

    2017-06-01

    Full Text Available When strong earthquake occurs, global navigation satellite systems (GNSS measurement errors increase significantly. Combined strategies of GNSS/accelerometer data can estimate better precision in displacement, but are of no help to carrier phase measurement. In this paper, strong-motion accelerometer-aided phase-locked loops (PLLs are proposed to improve carrier phase accuracy during strong earthquakes. To design PLLs for earthquake monitoring, the amplitude-frequency characteristics of the strong earthquake signals are studied. Then, the measurement errors of PLLs before and after micro electro mechanical systems (MEMS accelerometer aiding are analyzed based on error models. Furthermore, tests based on a hardware simulator and a shake table are carried out. Results show that, with MEMS accelerometer aiding, the carrier phase accuracy of the PLL decreases little under strong earthquakes, which is consistent with the models analysis.

  17. Hyperfine phononic frequency comb

    CERN Document Server

    Ganesan, Adarsh; Seshia, Ashwin A

    2016-01-01

    Optical frequency combs [1-8] have resulted in significant advances in optical frequency metrology and found wide application to precise physical measurements [1-4, 9] and molecular fingerprinting [8]. A direct analogue of frequency combs in the phononic or acoustic domain has not been reported to date. In this letter, we report the first clear experimental evidence for a phononic frequency comb. In contrast to the Kerr nonlinearity [10] in optical frequency comb formation, the phononic frequency comb is generated through the intrinsic coupling of a driven phonon mode with an auto-parametrically excited sub-harmonic mode [16]. Through systematic experiments at different drive frequencies and amplitudes, we portray the well-connected process of phononic frequency comb formation and define attributes to control the features [17-18] associated with comb formation in such a system. Further, the interplay between these nonlinear resonances and the well-known Duffing phenomenon [12-14] is also observed. The present...

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

    Science.gov (United States)

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

    2003-01-01

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

  19. Suspended biofilm carrier and activated sludge removal of acidic pharmaceuticals

    DEFF Research Database (Denmark)

    Falås, Per; Baillon-Dhumez, Aude; Andersen, Henrik Rasmus

    2012-01-01

    Removal of seven active pharmaceutical substances (ibuprofen, ketoprofen, naproxen, diclofenac, clofibric acid, mefenamic acid, and gemfibrozil) was assessed by batch experiments, with suspended biofilm carriers and activated sludge from several full-scale wastewater treatment plants. A distinct...... and attached solids for the carriers) of diclofenac, ketoprofen, gemfibrozil, clofibric acid and mefenamic acid compared to the sludges. Among the target pharmaceuticals, only ibuprofen and naproxen showed similar removal rates per unit biomass for the sludges and biofilm carriers. In contrast...

  20. An evaluation of low-cost payload carrier

    Science.gov (United States)

    Yost, V. H.

    1980-01-01

    Payload carrier designed for space vehicles is essentially cargo carrier that supports, positions, and protects various equipment and materials used in conducting experiments in weightless space environment. Proposed carrier entitled Materials Experiment Assembly II (MEA-II) is considered superior to previously developed models in size, weight, and cost to user. Structure is lightweight with insulated exterior and can be custom sized to meet user needs.

  1. A Multi-Carrier Scheduling Algorithm for LTE-Advanced

    DEFF Research Database (Denmark)

    Vulpe, Alexander; Mihovska, Albena D.; Prasad, Ramjee

    2013-01-01

    LTE-Advanced aims to provide a transmission bandwidth of 100 MHz by using Carrier Aggregation to aggregate LTE Rel. 8 carriers. In order to increase the system capacity, resource allocation becomes a very good tool, and, in the context of the existence of multiple Component Carriers in LTE-Advanc......Net scenario) that respects the 3GPP specifications. Numerical results show that this algorithm has better performances than the traditional Round Robin and Proportionally Fair resource scheduling algorithms....

  2. A Silicon Micromachined Gyroscope Driven by the Rotating Carrier Self

    Institute of Scientific and Technical Information of China (English)

    Fuxue Zhang; Xu Mao; Yu Liu; Nan Zhang; Wei Zhang

    2006-01-01

    This paper reported a silicon micromachined gyroscope which is driven by the rotating carrier's angular velocity, the silicon was manufactured by anisotropy etching. The design, fabrication and packing of the sensing element were introduced in the paper. The imitation experimentation and performance test have certificated that the principle of the gyroscope is correct and the gyroscope can be used to sense yawing or pitching angular velocity of the rotating carrier, and the angular velocity of the rotating carrier itself.

  3. Carrier Statistics and Quantum Capacitance Models of Graphene Nanoscroll

    Directory of Open Access Journals (Sweden)

    M. Khaledian

    2014-01-01

    schematic perfect scroll-like Archimedes spiral. The DOS model was derived at first, while it was later applied to compute the carrier concentration and quantum capacitance model. Furthermore, the carrier concentration and quantum capacitance were modeled for both degenerate and nondegenerate regimes, along with examining the effect of structural parameters and chirality number on the density of state and carrier concentration. Latterly, the temperature effect on the quantum capacitance was studied too.

  4. Static electromagnetic frequency changers

    CERN Document Server

    Rozhanskii, L L

    1963-01-01

    Static Electromagnetic Frequency Changers is about the theory, design, construction, and applications of static electromagnetic frequency changers, devices that used for multiplication or division of alternating current frequency. It is originally published in the Russian language. This book is organized into five chapters. The first three chapters introduce the readers to the principles of operation, the construction, and the potential applications of static electromagnetic frequency changers and to the principles of their design. The two concluding chapters use some hitherto unpublished work

  5. Modeling Frequency Comb Sources

    Directory of Open Access Journals (Sweden)

    Li Feng

    2016-06-01

    Full Text Available Frequency comb sources have revolutionized metrology and spectroscopy and found applications in many fields. Stable, low-cost, high-quality frequency comb sources are important to these applications. Modeling of the frequency comb sources will help the understanding of the operation mechanism and optimization of the design of such sources. In this paper,we review the theoretical models used and recent progress of the modeling of frequency comb sources.

  6. Kondo effect in low-carrier systems

    Energy Technology Data Exchange (ETDEWEB)

    Hager, R.; Bulla, R. [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Univ. Augsburg (Germany)

    2007-07-01

    Recent experiments on dilute U impurities in semiconducting CaB{sub 6} show typical Kondo phenomena with a Kondo temperature T{sub K}{approx}2 K (G.A. Wigger e.t al., Europhys. Lett. 68, 685 (2004)). This observation is rather unusual for magnetic moments due to 5f electrons because of the large hybridization between impurities and the conduction electrons. We perform numerical renormalization group calculations for an Anderson impurity model with a, low concentration of conduction electrons, believed to be the relevant model for (U,Ca)B{sub 6}. We present results for thermodynamic and dynamic quantities for various carrier concentrations and investigate the crossover from mixed-valent to Kondo behaviour upon decreasing the filling of the conduction band. (orig.)

  7. Carbon phosphide monolayers with superior carrier mobility

    Science.gov (United States)

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P.

    2016-04-01

    Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics.Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great

  8. Hot carrier injection degradation under dynamic stress

    Institute of Scientific and Technical Information of China (English)

    Ma Xiao-Hua; Cao Yan-Rong; Hao Yue; Zhang Yue

    2011-01-01

    In this paper, we have studied hot carrier injection (HCI) under alternant stress. Under different stress modes, different degradations are obtained from the experiment results. The different alternate stresses can reduce or enhance the HC effect, which mainly depends on the latter condition of the stress cycle. In the stress mode A (DC stress with electron injection), the degradation keeps increasing. In the stress modes B (DC stress and then stress with the smallest gate injection) and C (DC stress and then stress with hole injection under Vg=0V and Vd = 1.8 V), recovery appears in the second stress period. And in the stress mode D (DC stress and then stress with hole injection under Vg = -1.8 V and Vd = 1.8 V), as the traps filled in by holes can be smaller or greater than the generated interface states, the continued degradation or recovery in different stress periods can be obtained.

  9. Carrier Induced Magnetism In Correlated Materials

    Science.gov (United States)

    Lee, Byounghak; Trivedi, Nandini; Zhang, Shiwei; Martin, Richard

    2003-03-01

    We study a two dimensional Hubbard model with magnetic impurities using a combination of single particle and quantum Monte Carlo techniques. Our aim is to determine the interaction between magnetic ions in both strongly interacting hosts, such as magnetic perovskites, and weakly interacting hosts, such as magnetic semiconductors. In the first step, the interactions are treated within an inhomogeneous Hartree-Fock approach and self-consistency is demanded at each site, providing a more accurate treatment of disorder effects compared with other mean-field treatments such as virtual crystal and coherent potential approximations. These are then augmented with determinantal quantum Monte Carlo techniques that treat the electron interactions more accurately. We calculate the exchange coupling as a function of the magnetic impurity concentration, the repulsive electron-electron interaction, carrier concentration, and temperature. We compare the calculated local density of states with STM measurements and also obtain the ferromagnetic transition temperature.

  10. Effective information rates of single-carrier and multi-carrier modulation schemes for bandwidth constrained IM/DD systems

    KAUST Repository

    Mazahir, Sana

    2017-07-31

    Information-theoretic and signal processing aspects of some modulation schemes designed for intensity modulation/direct detection (IM/DD) optical wireless communication (OWC) systems are studied. Due to the constraints of IM/DD signals (non-negative real and baseband signals), the construction of these signals along with their time and frequency characteristics differ from their RF counterparts. This necessitates a careful study of such schemes under practical constraints. Three schemes are studied in this paper, namely, single carrier pulse amplitude modulation (SC-PAM), asymmetrically clipped optical OFDM (ACO-OFDM), and DC biased optical OFDM (DCO-OFDM). Our aim is to carry out a comparative study of these schemes in the presence of identical constraints on bandwidth and average optical power. The study reveals that the clipping operation required in ACO-OFDM significantly reduces its information rate, and as a result, it is outperformed by SC-PAM. Such a limitation does not apply to DCO-OFDM which has a higher information rate, even though part of the available optical power is expended in the non-information-bearing DC bias.

  11. Study of frequency and time responses of a separated absorption and multiplication region avalanche photodiode

    CERN Document Server

    Banoushi, A; Setayeshi, S

    2003-01-01

    In this paper, the frequency and time responses of a separated absorption and multiplication avalanche photodiode are studied by solving the carrier continuity equations, in the low gain regime. The discrepancy between the carrier velocities in different layers is considered for the first time. It is shown that considerable error occurs, if the device d characteristics are calculated assuming uniformly distributed velocities in the depletion layer, especially when the different layers have almost equal thickness.

  12. Obstacle avoidance and path planning for carrier aircraft launching

    Directory of Open Access Journals (Sweden)

    Wu Yu

    2015-06-01

    Full Text Available Launching safety and efficiency are important indexes to measure the fighting capacity of carrier. The study on path planning for taxi of carrier aircraft launching under actual deck environment is of great significance. In actual deck scheduling, manual command is applied to taxi of carrier aircraft, which has negative effects on the safety of staff and carrier aircraft launching. In consideration of both the safety and efficiency of carrier aircraft launching, the key elements of the problem are abstracted based on the analysis of deck environment, carrier aircraft maneuver performance and task requirements. According to the problem description, the mathematical model is established including various constraints. The carrier aircraft and the obstacles are reasonably simplified as circle and polygons respectively. What’s more, the proposed collision detection model reduces the calculations. Aimed at the features of model, the theory of model predictive control (MPC is applied to the path search. Then a dynamic weight heuristic function is designed and a dynamic multistep optimization algorithm is proposed. Taking the Nimitz-class aircraft carrier as an example, the paths from parking place to catapult are planned, which indicate the rationality of the model and the effectiveness of the algorithm by comparing the planning results under different simulation environments. The main contribution of research is the establishment of obstacle avoidance and path planning model. In addition, it provides the solution of model and technological foundations for comprehensive command and real-time decision-making of the carrier aircraft.

  13. Skewed X inactivation in Lesch-Nyhan disease carrier females.

    Science.gov (United States)

    Torres, Rosa J; Puig, Juan G

    2017-09-14

    X chromosome inactivation (XCI) ratios of normal females can range from a highly skewed ratio of 0:100 to a 50:50 ratio. In several X-linked disorders, female carriers present skewed X inactivation. Hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency is an X-linked disorder. Males are affected and present with the complete Lesch-Nyhan disease (LND) or with a partial phenotype (Lesch-Nyhan variant, LNV). Female carriers are usually asymptomatic. The aim of the present study was to analyze the XCI pattern of HPRT-deficiency carrier females. As a group, 75% of HPRT-deficiency carrier females presented skewed XCI. Moreover, skewed XCI is significantly more frequent in LND carriers (83%) than in LNV (0-50%, depending on the phenotype severity). The ratios of the preferentially inactivated allele of carrier females were significantly higher than the ratios of the preferentially inactivated allele of noncarrier females (89.4±15, n=52 vs 65.2±12, n=52; P<0.0001). For carrier diagnosis, the presence of skewed XCI presents a sensitivity of 75% with a specificity of 85%. In LND families, the presence of skewed XCI is more sensitive for carrier diagnosis than in LNV families; however, we believe that this test is not accurate for carrier diagnostic purposes.Journal of Human Genetics advance online publication, 14 September 2017; doi:10.1038/jhg.2017.88.

  14. Eastern Frequency Response Study

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-01

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

  15. Experimental demonstration of sub-Fourier structures in time--frequency measurement of light pulses

    CERN Document Server

    Praxmeyer, L; Radzewicz, C; Wodkiewicz, K; Praxmeyer, Ludmila; Wasylczyk, Piotr; Radzewicz, Czeslaw; Wodkiewicz, Krzysztof

    2006-01-01

    We present experimental data of the frequency resolved optical gating (FROG) measurements of light pulses revealing interference features corresponding to sub-Planck structures in phase space. For superpositions of pulses a small, sub-Fourier shift in the carrier frequency leads to a state orthogonal to the initial one, although in the representation of standard time--frequency distributions these states seem to have a non-vanishing overlap.

  16. Direct Spectroscopy in Hollow Optical with Fiber-Based Optical Frequency Combs

    Science.gov (United States)

    2015-07-09

    stabilization To fully stabilize the comb, there are three servo loops, shown in Fig. 1, that lock the carrier offset frequency f0 to an RF synthesizer ...GPS-Rb oscillator serves as the external reference for all synthesizers and frequency counters. The filtering cavity is stabilized to a particular...filled frequency reference in a 10 m length. Since optimal single-modedness is expected at longer lengths (~10-30 m), a gas such as ammonia , with weaker

  17. A NOVEL INTEGER FREQUENCY OFFSET ESTIMATOR FOR OFDM

    Institute of Scientific and Technical Information of China (English)

    Cai Xuelian; Li Jiandong; Li Changle; Chen Chen

    2005-01-01

    One of the principal disadvantages of Orthogonal Frequency Division Multiplexing (OFDM) is very sensitive to carrier frequency offset. The integer frequency offset has no effect on the orthogonality among the subcarriers, but it causes a circular shift and phase rotation of the received data symbols sequence, resulting in a Bit Error Rate(BER) of 0.5. In this paper,a novel integer frequency offset estimator for OFDM is derived based on maximum likelihood estimation technique and exploration of the differential relation between two consecutive OFDM data symbol sequences in frequency domain. Its performance is compared with the conventional method by computer simulations for the additive white Gaussian noise channel and a multipath fading channel. Simulation results show that the performance of the proposed estimator is better than the conventional estimator.

  18. Frequency selective infrared sensors

    Science.gov (United States)

    Davids, Paul; Peters, David W

    2013-05-28

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

  19. Carrier-Envelope Offset Stabilized Ultrafast Diode-Pumped Solid-State Lasers

    Directory of Open Access Journals (Sweden)

    Stéphane Schilt

    2015-10-01

    Full Text Available Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs have become an attractive alternative with state-of-the-art performance. In this article, we review the main achievements in ultrafast DPSSLs for frequency combs. We present the current status of carrier-envelope offset (CEO frequency-stabilized DPSSLs based on various approaches and operating in different wavelength regimes. Feedback to the pump current provides a reliable scheme for frequency comb CEO stabilization, but also other methods with faster feedback not limited by the lifetime of the gain material have been applied. Pumping DPSSLs with high power multi-transverse-mode diodes enabled a new class of high power oscillators and gigahertz repetition rate lasers, which were initially not believed to be suitable for CEO stabilization due to the pump noise. However, this challenge has been overcome, and recently both high power and gigahertz DPSSL combs have been demonstrated. Thin disk lasers have demonstrated the highest pulse energy and average power emitted from any ultrafast oscillator and present a high potential for the future generation of stabilized frequency combs with hundreds of watts average output power.

  20. An Ashkenazi Jewish SMN1 haplotype specific to duplication alleles improves pan-ethnic carrier screening for spinal muscular atrophy.

    Science.gov (United States)

    Luo, Minjie; Liu, Liu; Peter, Inga; Zhu, Jun; Scott, Stuart A; Zhao, Geping; Eversley, Chevonne; Kornreich, Ruth; Desnick, Robert J; Edelmann, Lisa

    2014-02-01

    Spinal muscular atrophy is a common autosomal-recessive disorder caused by mutations of the SMN1 gene. Spinal muscular atrophy carrier screening uses dosage-sensitive methods that determine SMN1 copy number, and the frequency of carriers varies by ethnicity, with detection rates ranging from 71 to 94% due to the inability to identify silent (2 + 0) carriers with two copies of SMN1 on one chromosome 5 and deletion on the other. We hypothesized that identification of deletion and/or duplication founder alleles might provide an approach to identify silent carriers in various ethnic groups. SMN1 founder alleles were investigated in the Ashkenazi Jewish population by microsatellite analysis and next-generation sequencing. An extended haplotype block, specific to Ashkenazi Jewish SMN1 duplications, was identified by microsatellite analysis, and next-generation sequencing of SMN1 further defined a more localized haplotype. Of note, six novel SMN1 sequence variants were identified that were specific to duplications and not present on single-copy alleles. The haplotype was also identified on SMN1 duplication alleles in additional ethnic groups. Identification of these novel variants in an individual with two copies of SMN1 significantly improves the accuracy of residual risk estimates and has important implications for spinal muscular atrophy carrier screening.