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Sample records for beta frequency band

  1. Rectification of EMG in low force contractions improves detection of motor unit coherence in the beta-frequency band.

    Science.gov (United States)

    Ward, Nicholas J; Farmer, Simon F; Berthouze, Luc; Halliday, David M

    2013-10-01

    Rectification of surface EMG before spectral analysis is a well-established preprocessing method used in the detection of motor unit firing patterns. A number of recent studies have called into question the need for rectification before spectral analysis, pointing out that there is no supporting experimental evidence to justify rectification. We present an analysis of 190 records from 13 subjects consisting of simultaneous recordings of paired single motor units and surface EMG from the extensor digitorum longus muscle during middle finger extension against gravity (unloaded condition) and against gravity plus inertial loading (loaded condition). We directly examine the hypothesis that rectified surface EMG is a better predictor of the frequency components of motor unit synchronization than the unrectified (or raw) EMG in the beta-frequency band (15-32 Hz). We use multivariate analysis and estimate the partial coherence between the paired single units using both rectified and unrectified surface EMG as a predictor. We use a residual partial correlation measure to quantify the difference between raw and rectified EMG as predictor and analyze unloaded and loaded conditions separately. The residual correlation for the unloaded condition is 22% with raw EMG and 3.5% with rectified EMG and for the loaded condition it is 5.2% with raw EMG and 1.4% with rectified EMG. We interpret these results as strong supporting experimental evidence in favor of using the preprocessing step of surface EMG rectification before spectral analysis.

  2. Effect of Sertraline on Current-Source Distribution of the High Beta Frequency Band: Analysis of Electroencephalography under Audiovisual Erotic Stimuli in Healthy, Right-Handed Males

    OpenAIRE

    Lee, Seung Hyun; Hyun, Jae Seog; Kwon, Oh-Young

    2010-01-01

    Purpose The purpose of this study was to examine the cerebral changes in high beta frequency oscillations (22-30 Hz) induced by sertraline and by audiovisual erotic stimuli in healthy adult males. Materials and Methods Scalp electroencephalographies (EEGs) were conducted twice in 11 healthy, right-handed males, once before sertraline intake and again 4 hours thereafter. The EEGs included four sessions recorded sequentially while the subjects were resting, watching a music video, resting, and ...

  3. Neural oscillations: beta band activity across motor networks.

    Science.gov (United States)

    Khanna, Preeya; Carmena, Jose M

    2015-06-01

    Local field potential (LFP) activity in motor cortical and basal ganglia regions exhibits prominent beta (15-40Hz) oscillations during reaching and grasping, muscular contraction, and attention tasks. While in vitro and computational work has revealed specific mechanisms that may give rise to the frequency and duration of this oscillation, there is still controversy about what behavioral processes ultimately drive it. Here, simultaneous behavioral and large-scale neural recording experiments from non-human primate and human subjects are reviewed in the context of specific hypotheses about how beta band activity is generated. Finally, a new experimental paradigm utilizing operant conditioning combined with motor tasks is proposed as a way to further investigate this oscillation. PMID:25528615

  4. Reduced beta band connectivity during number estimation in autism

    Directory of Open Access Journals (Sweden)

    Katrin A. Bangel

    2014-01-01

    Full Text Available Recent evidence suggests that disruption of integrative processes in sensation and perception may play a critical role in cognitive and behavioural atypicalities characteristic of ASD. In line with this, ASD is associated with altered structural and functional brain connectivity and atypical patterns of inter-regional communication which have been proposed to contribute to cognitive difficulties prevalent in this group. The present MEG study used atlas-guided source space analysis of inter-regional phase synchronization in ASD participants, as well as matched typically developing controls, during a dot number estimation task. This task included stimuli with globally integrated forms (animal shapes as well as randomly-shaped stimuli which lacked a coherent global pattern. Early task-dependent increases in inter-regional phase synchrony in theta, alpha and beta frequency bands were observed. Reduced long-range beta-band phase synchronization was found in participants with ASD at 70–145 ms during presentation of globally coherent dot patterns. This early reduction in task-dependent inter-regional connectivity encompassed numerous areas including occipital, parietal, temporal, and frontal lobe regions. These results provide the first evidence for inter-regional phase synchronization during numerosity estimation, as well as its alteration in ASD, and suggest that problems with communication among brain areas may contribute to difficulties with integrative processes relevant to extraction of meaningful ‘Gestalt’ features in this population.

  5. ISM band to U-NII band frequency transverter and method of frequency transversion

    Science.gov (United States)

    Stepp, Jeffrey David; Hensley, Dale

    2006-09-12

    A frequency transverter (10) and method for enabling bi-frequency dual-directional transfer of digitally encoded data on an RF carrier by translating between a crowded or otherwise undesirable first frequency band, such as the 2.4 GHz ISM band, and a less-crowded or otherwise desirable second frequency band, such as the 5.0 GHz 6.0 GHz U-NII band. In a preferred embodiment, the transverter (10) connects between an existing data radio (11) and its existing antenna (30), and comprises a bandswitch (12); an input RF isolating device (14); a transmuter (16); a converter (18); a dual output local oscillator (20); an output RF isolating device (22); and an antenna (24) tuned to the second frequency band. The bandswitch (12) allows for bypassing the transverter (10), thereby facilitating its use with legacy systems. The transmuter (14) and converter (16) are adapted to convert to and from, respectively, the second frequency band.

  6. Asymmetric acoustic transmission in multiple frequency bands

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hong-xiang, E-mail: jsdxshx@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhang, Shu-yi [Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-11-23

    We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices.

  7. Wide band stepped frequency ground penetrating radar

    Science.gov (United States)

    Bashforth, Michael B.; Gardner, Duane; Patrick, Douglas; Lewallen, Tricia A.; Nammath, Sharyn R.; Painter, Kelly D.; Vadnais, Kenneth G.

    1996-01-01

    A wide band ground penetrating radar system (10) embodying a method wherein a series of radio frequency signals (60) is produced by a single radio frequency source (16) and provided to a transmit antenna (26) for transmission to a target (54) and reflection therefrom to a receive antenna (28). A phase modulator (18) modulates those portion of the radio frequency signals (62) to be transmitted and the reflected modulated signal (62) is combined in a mixer (34) with the original radio frequency signal (60) to produce a resultant signal (53) which is demodulated to produce a series of direct current voltage signals (66) the envelope of which forms a cosine wave shaped plot (68) which is processed by a Fast Fourier Transform unit 44 into frequency domain data (70) wherein the position of a preponderant frequency is indicative of distance to the target (54) and magnitude is indicative of the signature of the target (54).

  8. Frequency Arrangement For 700 MHz Band

    Directory of Open Access Journals (Sweden)

    Ancans G.

    2015-02-01

    Full Text Available The 694-790 MHz (700 MHz band was allocated by the 2012 World Radiocommunication Conference (WRC-12 in ITU Region 1 (Europe included, to the mobile service on a co-primary basis with other services to which this band was allocated on the primary basis and identified for the International Mobile Telecommunications (IMT. At the same time, the countries of Region 1 will be able also to continue using these frequencies for their broadcasting services if necessary. This allocation will be effective immediately after 2015 World Radiocommunication Conference (WRC-15. In order to make the best possible use of this frequency band for mobile service, a worldwide harmonized frequency arrangement is to be prepared to allow for large economies of scale and international roaming as well as utilizing the available spectrum in the best possible way, minimizing possible interference between services, facilitating deployment and cross-border coordination. The authors analyze different possible frequency arrangements and conclude on the frequency arrangement most suitable for Europe.

  9. Dopaminergic therapy in Parkinson's disease decreases cortical beta band coherence in the resting state and increases cortical beta band power during executive control.

    Science.gov (United States)

    George, Jobi S; Strunk, Jon; Mak-McCully, Rachel; Houser, Melissa; Poizner, Howard; Aron, Adam R

    2013-01-01

    It is not yet well understood how dopaminergic therapy improves cognitive and motor function in Parkinson's disease (PD). One possibility is that it reduces the pathological synchronization within and between the cortex and basal ganglia, thus improving neural communication. We tested this hypothesis by recording scalp electroencephalography (EEG) in PD patients when On and Off medication, during a brief resting state epoch (no task), and during performance of a stop signal task that is thought to engage two partially overlapping (or different) frontal-basal-ganglia circuits. For resting state EEG, we measured pair-wise coherence between scalp electrodes in several frequency bands. Consistent with previous studies, in the Off medication state, those patients with the greatest clinical impairment had the strongest coherence, especially in the beta band, indicating pathological over-synchronization. Dopaminergic medication reduced this coherence. For the stop signal task, On vs. Off medication increased beta band power over right frontal cortex for successful stopping and over bilateral sensorimotor cortex for going, especially for those patients who showed greater clinical improvement. Thus, medication reduced pathological coherence in beta band at rest and increased task related beta power for two potentially dissociable cortico-basal ganglia circuits. These results support the hypothesis that dopaminergic medication in PD improves neural communication both at rest and for executive and motor function.

  10. Saliency computation via whitened frequency band selection.

    Science.gov (United States)

    Lv, Qi; Wang, Bin; Zhang, Liming

    2016-06-01

    Many saliency computational models have been proposed to simulate bottom-up visual attention mechanism of human visual system. However, most of them only deal with certain kinds of images or aim at specific applications. In fact, human beings have the ability to correctly select attentive focuses of objects with arbitrary sizes within any scenes. This paper proposes a new bottom-up computational model from the perspective of frequency domain based on the biological discovery of non-Classical Receptive Field (nCRF) in the retina. A saliency map can be obtained according to the idea of Extended Classical Receptive Field. The model is composed of three major steps: firstly decompose the input image into several feature maps representing different frequency bands that cover the whole frequency domain by utilizing Gabor wavelet. Secondly, whiten the feature maps to highlight the embedded saliency information. Thirdly, select some optimal maps, simulating the response of receptive field especially nCRF, to generate the saliency map. Experimental results show that the proposed algorithm is able to work with stable effect and outstanding performance in a variety of situations as human beings do and is adaptive to both psychological patterns and natural images. Beyond that, biological plausibility of nCRF and Gabor wavelet transform make this approach reliable. PMID:27275381

  11. Selection of Ka-Band Transponder Turnaround Frequency Ratio

    Science.gov (United States)

    Koukos, J.

    1993-01-01

    The Consultative Committee for Space Data Systems has issued recommendations specifying Transponder Turn-around Frequency Ratios for S-band and X-band coherent earth-to-space and space-to earth links.

  12. Dual-band frequency selective surface with large band separation and stable performance

    Institute of Scientific and Technical Information of China (English)

    Zhou Hang; Xu Zhuo; Qu Shao-Bo; Peng Wei-Dong; Lin Bao-Qin; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Bai Peng; Wang Xu-Hua

    2012-01-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented.This technique is based on a delicately designed topology of L-and Ku-band microwave filters.The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface,respectively.A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings.Based on this technique,a dual-band frequency selective surface with large band separation is designed,which possesses large band separation,high selectivity,and stable performance under various incident angles and different polarizations.

  13. Listening to the low-frequency gravitational-wave band

    Science.gov (United States)

    Hughes, Scott

    2016-03-01

    Ground-based gravitational-wave detectors are beginning to explore the high-frequency band of roughly 10 to 1000 Hz. These three decades in frequency represent one of several astrophysically important wavebands. In this talk, I will focus on the astrophysics of the low-frequency band, from roughly 30 microhertz to 0.1 Hz. This band is expected to be particularly rich with very loud sources. I will survey what we expect to be important sources of low-frequency gravitational waves, and review the scientific payoff that would come from measuring them.

  14. Banding ligation versus beta-blockers as primary prophylaxis in esophageal varices

    DEFF Research Database (Denmark)

    Gluud, Lise L; Klingenberg, Sarah; Nikolova, Dimitrinka;

    2007-01-01

    To compare banding ligation versus beta-blockers as primary prophylaxis in patients with esophageal varices and no previous bleeding.......To compare banding ligation versus beta-blockers as primary prophylaxis in patients with esophageal varices and no previous bleeding....

  15. A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.

    2015-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

  16. [IMPACT OF INDIVIDUAL PERSONALITY FEATURES ON ABILITY TO VOLUNTARY REGULATION OF EXPRESSION EEG ALPHA AND BETA FREQUENCIES].

    Science.gov (United States)

    Aslanyan, E V; Kiroy, V N; Stoletniy, A S; Lazurenko, D M; Bahtin, O M; Minyaeva, N R; Kiroy, R I

    2015-05-01

    The ability to voluntary control severity of alpha- and beta-2 frequency bands in the parietal and frontal cortical areas was investigated at 17 volunteers using biofeedback. The impact of different personality traits on the effectiveness of control was evaluated. According to the data, it was easier task to decrease expression beta-2 frequency in the frontal cortex than to decline the power of alpha frequency in the parietal cortex. The effectiveness of voluntary control of brain activity is influenced by personality features as extraversion, psychoticism, neuroticism, mobility and steadiness of nerve processes, level of person anxiety. PMID:26263685

  17. Banding ligation versus beta-blockers for primary prevention in oesophageal varices in adults

    DEFF Research Database (Denmark)

    Gluud, Lise Lotte; Krag, Aleksander

    2012-01-01

    Non-selective beta-blockers are used as a first-line treatment for primary prevention in patients with medium- to high-risk oesophageal varices. The effect of non-selective beta-blockers on mortality is debated and many patients experience adverse events. Trials on banding ligation versus non......-selective beta-blockers for patients with oesophageal varices and no history of bleeding have reached equivocal results....

  18. Low-loss Ka-band frequency selective subreflector

    Science.gov (United States)

    Ueno, K.; Kumazawa, H.; Ohtomo, I.

    1991-06-01

    A frequency selective subreflector with two separate focal fed positions for a 30/20 GHz offset Gregorian reflector antenna is developed. For a bandwidth exceeding 3 GHz in the 20 and 30 GHz band, the measured losses are 0.7 and 1.5 dB, respectively.

  19. K-Band Radio frequency Interference Survey of Southeastern Michigan

    DEFF Research Database (Denmark)

    Curry, Shannon; Ahlers, Michael Faursby; Elliot, Harvey;

    2010-01-01

    The Radio frequency Interference Survey of Earth (RISE) is a new type of instrument used to survey and characterize the presence of Radio Frequency Interference (RFI) that can affect microwave radiometers. It consists of a combined microwave radiometer and kurtosis spectrometer with broad frequency...... coverage and high temporal and spectral resolution. A K-Band airborne version has been built and flown across southeast Michigan. A kurtosis detector is included in RISE to reliably detect the presence of RFI, even at very low levels, and to aid in its characterization. A radiometer is included to measure...... the impact of the RFI on observed brightness temperature....

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

    Science.gov (United States)

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

    2014-01-13

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

  1. Design of S-Band Frequency Synthesizer for Microwave Applications

    Directory of Open Access Journals (Sweden)

    S. Shurender

    2013-08-01

    Full Text Available A phase locked loop based indirect frequency synthesizer is designed for S-band frequency. A Phase locked loop is designed and the phase noise response and transient response of the designed PLL is simulated for 2100MHz frequency. The phase noise response of total PLL and its individual components are obtained. A 3rd order low pass passive loop filter is used and by varying the loop bandwidth and phase margin the trade-off between lock time and phase noise is observed and an optimum value of loop bandwidth and phase margin is chosen such that its phase noise contribution is less. The designed phase locked loop has a low phase noise value of -112.4dBc/Hz at 100 kHz offset frequency and has a fast lock time of 119.5 us. The time taken by the designed frequency synthesizer to lock to 10 Hz frequency error and 1° phase error under transient conditions is found to be 149 us and 116 us respectively. The RMS phase jitter obtained for the designed phase locked loop is 0.3° rms. The phase locked loop is designed and simulated using ADIsimPLL tool. The phase locked loop design aims at achieving low phase noise, reduced lock time and high reliability for S-band applications.

  2. High-frequency homogenization of zero frequency stop band photonic and phononic crystals

    CERN Document Server

    Antonakakis, Tryfon; Guenneau, Sebastien

    2013-01-01

    We present an accurate methodology for representing the physics of waves, for periodic structures, through effective properties for a replacement bulk medium: This is valid even for media with zero frequency stop-bands and where high frequency phenomena dominate. Since the work of Lord Rayleigh in 1892, low frequency (or quasi-static) behaviour has been neatly encapsulated in effective anisotropic media. However such classical homogenization theories break down in the high-frequency or stop band regime. Higher frequency phenomena are of significant importance in photonics (transverse magnetic waves propagating in infinite conducting parallel fibers), phononics (anti-plane shear waves propagating in isotropic elastic materials with inclusions), and platonics (flexural waves propagating in thin-elastic plates with holes). Fortunately, the recently proposed high-frequency homogenization (HFH) theory is only constrained by the knowledge of standing waves in order to asymptotically reconstruct dispersion curves an...

  3. ICRF [Ion Cyclotron Range of Frequencies] heating and antenna coupling in a high beta tokamak

    International Nuclear Information System (INIS)

    Maxwell's Equations are solved in two-dimensions for the electromagnetic fields in a toroidal cavity using the cold plasma fluid dielectric tensor in the Ion Cyclotron Range of Frequencies (ICRF). The Vector Wave Equation is transformed to a set of two, coupled second-order partial differential equations with inhomogeneous forcing functions which model a wave launcher. The resulting equations are finite differenced and solved numerically with a complex banded matrix algorithm on a Cray-2 computer using a code described in this report. This code is used to study power coupling characteristics of a wave launcher for low and high beta tokamaks. The low and high beta equilibrium tokamak magnetic fields applied in this model are determined from analytic solutions to the Grad-Shafranov equation. The code shows good correspondence with the results of low field side ICRF heating experiments performed on the Tokamak of Fontenay-Aux-Roses (TFR). Low field side and high field side antenna coupling properties for ICRF heating in the Columbia High Beta Tokamak (HBT) experiment are calculated with this code. Variations of antenna position in the tokamak, ionic concentration and plasma density, and volume-averaged beta have been analyzed for HBT. It is found that the location of the antenna with respect to the plasma has the dominant role in the design of an ICRF heating experiment in HBT. 10 refs., 52 figs., 13 tabs

  4. A center frequency adjustable narrow band filter for the detection of weak single frequency signal.

    Science.gov (United States)

    Xin, Yunhong; Xiang, ZhenMing; Dong, LeMing; Zhu, Bing; Cao, Hui; Fang, Yu

    2014-04-01

    We describe and implement a center frequency adjustable narrow band filter based on the crystal filter for the detection of weak single frequency signal. It is formed by a multiplier, a direct digital frequency synthesizer, a multi-stage crystal bandpass filter, and a micro control unit which is used to set the center frequency of the filter. A theoretical study is proposed and experimentally validated. The test results show that the 3 db and 20 db bandwidths are 0.84 Hz and 2.73 Hz, respectively, and the filter system can effectively detect the signal with amplitude below 1 μV and a frequency which ranges from 10 Hz to the frequency that is mainly limited by the components applied.

  5. Specific frequency bands of amplitude low-frequency oscillation encodes personality.

    Science.gov (United States)

    Wei, Luqing; Duan, Xujun; Zheng, Chunyan; Wang, Shanshan; Gao, Qing; Zhang, Zhiqiang; Lu, Guangming; Chen, Huafu

    2014-01-01

    The biological model of extraversion and neuroticism identified by Eysenck has stimulated increasing interest in uncovering neurobiological substrate of the two fundamental dimensions. Here we aim to explore brain disturbances underlying extraversion and neuroticism in 87 healthy individuals using fractional amplitude of low-frequency fluctuations (LFF) on resting-state functional magnetic resonance imaging. Two different frequency bands, Slow-5 (0.01-0.027 Hz) exhibiting higher power and involving larger brain regions, and Slow-4 (0.027-0.073 Hz) exhibiting less power and emerging locally, were analyzed. Our results showed a positive correlation between LFF amplitude at Slow-5 and extraversion in medial prefrontal cortex and precuneus, important portions of the default mode network, thus suggesting a link between default network activity and personality traits. LFF amplitude at Slow-5 was correlated positively with neuroticism in right posterior portion of the frontal lobe, further validating neuroticism with frontal lateralization. In addition, LFF amplitude at Slow-4 was negatively associated with extraversion and neuroticism in left hippocampus (HIP) and bilateral superior temporal cortex (STC) respectively, supporting the hypothesized (inverse) relationship between extraversion and resting arousal, also implying neural circuit underlying emotional process influencing on personality. Overall, these findings suggest the important relationships, between personality and LFF amplitude dynamic, depend on specific frequency bands.

  6. Early and late beta-band power reflect audiovisual perception in the McGurk illusion.

    Science.gov (United States)

    Roa Romero, Yadira; Senkowski, Daniel; Keil, Julian

    2015-04-01

    The McGurk illusion is a prominent example of audiovisual speech perception and the influence that visual stimuli can have on auditory perception. In this illusion, a visual speech stimulus influences the perception of an incongruent auditory stimulus, resulting in a fused novel percept. In this high-density electroencephalography (EEG) study, we were interested in the neural signatures of the subjective percept of the McGurk illusion as a phenomenon of speech-specific multisensory integration. Therefore, we examined the role of cortical oscillations and event-related responses in the perception of congruent and incongruent audiovisual speech. We compared the cortical activity elicited by objectively congruent syllables with incongruent audiovisual stimuli. Importantly, the latter elicited a subjectively congruent percept: the McGurk illusion. We found that early event-related responses (N1) to audiovisual stimuli were reduced during the perception of the McGurk illusion compared with congruent stimuli. Most interestingly, our study showed a stronger poststimulus suppression of beta-band power (13-30 Hz) at short (0-500 ms) and long (500-800 ms) latencies during the perception of the McGurk illusion compared with congruent stimuli. Our study demonstrates that auditory perception is influenced by visual context and that the subsequent formation of a McGurk illusion requires stronger audiovisual integration even at early processing stages. Our results provide evidence that beta-band suppression at early stages reflects stronger stimulus processing in the McGurk illusion. Moreover, stronger late beta-band suppression in McGurk illusion indicates the resolution of incongruent physical audiovisual input and the formation of a coherent, illusory multisensory percept.

  7. Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method)

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

    Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf......Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf...

  8. Can comodulation masking release occur when frequency changes could promote perceptual segregation of the on-frequency and flanking bands?

    DEFF Research Database (Denmark)

    Verhey, Jesko L; Epp, Bastian; Stasiak, Arkadiusz;

    2013-01-01

    A common characteristic of natural sounds is that the level fluctuations in different frequency regions are coherent. The ability of the auditory system to use this comodulation is shown when a sinusoidal signal is masked by a masker centred at the signal frequency (on-frequency masker, OFM...... and comodulation could serve as cues to indicate which of the stimulus components originate from one source. If the common fate of frequency components is the stronger binding cue, the sweeping FBs and the OFM with a fixed centre frequency should no longer form one auditory object and the CMR should be abolished...... bands relative to the inhibitory areas (as seen in physiological recordings using stationary flanking bands). Preliminary physiological results in the cochlear nucleus of the Guinea pig show that a correlate of CMR can also be found at this level of the auditory pathway with sweeping flanking bands....

  9. What can be found in scalp EEG spectrum beyond common frequency bands. EEG–fMRI study

    Science.gov (United States)

    Marecek, R.; Lamos, M.; Mikl, M.; Barton, M.; Fajkus, J.; I, Rektor; Brazdil, M.

    2016-08-01

    Objective. The scalp EEG spectrum is a frequently used marker of neural activity. Commonly, the preprocessing of EEG utilizes constraints, e.g. dealing with a predefined subset of electrodes or a predefined frequency band of interest. Such treatment of the EEG spectrum neglects the fact that particular neural processes may be reflected in several frequency bands and/or several electrodes concurrently, and can overlook the complexity of the structure of the EEG spectrum. Approach. We showed that the EEG spectrum structure can be described by parallel factor analysis (PARAFAC), a method which blindly uncovers the spatial–temporal–spectral patterns of EEG. We used an algorithm based on variational Bayesian statistics to reveal nine patterns from the EEG of 38 healthy subjects, acquired during a semantic decision task. The patterns reflected neural activity synchronized across theta, alpha, beta and gamma bands and spread over many electrodes, as well as various EEG artifacts. Main results. Specifically, one of the patterns showed significant correlation with the stimuli timing. The correlation was higher when compared to commonly used models of neural activity (power fluctuations in distinct frequency band averaged across a subset of electrodes) and we found significantly correlated hemodynamic fluctuations in simultaneously acquired fMRI data in regions known to be involved in speech processing. Further, we show that the pattern also occurs in EEG data which were acquired outside the MR machine. Two other patterns reflected brain rhythms linked to the attentional and basal ganglia large scale networks. The other patterns were related to various EEG artifacts. Significance. These results show that PARAFAC blindly identifies neural activity in the EEG spectrum and that it naturally handles the correlations among frequency bands and electrodes. We conclude that PARAFAC seems to be a powerful tool for analysis of the EEG spectrum and might bring novel insight to the

  10. What can be found in scalp EEG spectrum beyond common frequency bands. EEG-fMRI study

    Science.gov (United States)

    Marecek, R.; Lamos, M.; Mikl, M.; Barton, M.; Fajkus, J.; I, Rektor; Brazdil, M.

    2016-08-01

    Objective. The scalp EEG spectrum is a frequently used marker of neural activity. Commonly, the preprocessing of EEG utilizes constraints, e.g. dealing with a predefined subset of electrodes or a predefined frequency band of interest. Such treatment of the EEG spectrum neglects the fact that particular neural processes may be reflected in several frequency bands and/or several electrodes concurrently, and can overlook the complexity of the structure of the EEG spectrum. Approach. We showed that the EEG spectrum structure can be described by parallel factor analysis (PARAFAC), a method which blindly uncovers the spatial-temporal-spectral patterns of EEG. We used an algorithm based on variational Bayesian statistics to reveal nine patterns from the EEG of 38 healthy subjects, acquired during a semantic decision task. The patterns reflected neural activity synchronized across theta, alpha, beta and gamma bands and spread over many electrodes, as well as various EEG artifacts. Main results. Specifically, one of the patterns showed significant correlation with the stimuli timing. The correlation was higher when compared to commonly used models of neural activity (power fluctuations in distinct frequency band averaged across a subset of electrodes) and we found significantly correlated hemodynamic fluctuations in simultaneously acquired fMRI data in regions known to be involved in speech processing. Further, we show that the pattern also occurs in EEG data which were acquired outside the MR machine. Two other patterns reflected brain rhythms linked to the attentional and basal ganglia large scale networks. The other patterns were related to various EEG artifacts. Significance. These results show that PARAFAC blindly identifies neural activity in the EEG spectrum and that it naturally handles the correlations among frequency bands and electrodes. We conclude that PARAFAC seems to be a powerful tool for analysis of the EEG spectrum and might bring novel insight to the

  11. Evolution of narrow band - high frequency hearing in odontocetes

    DEFF Research Database (Denmark)

    Miller, Lee A.; Galatius, Anders; Olsen, Morten Tange;

    2015-01-01

    Whale biologists generally agree that predation by killer whales provided selection pressure for driving up the biosonar frequencies of some odontocetes. This made the signals of these species, like the harbor porpoise, less audible to their predator. But why should the acoustic signals of 13 to 15...... known species in four families have peak frequencies between 120 kHz and 140 kHz? We propose and argue that at these frequencies an ambient noise minimum exists and has so over the past 10 million years or more. The spectral properties of the signals produced by smaller odontocetes, like the harbor...

  12. Low-frequency band gap mechanism of torsional vibration of lightweight elastic metamaterial shafts

    Science.gov (United States)

    Li, Lixia; Cai, Anjiang

    2016-07-01

    In this paper, the low-frequency band gap mechanism of torsional vibration is investigated for a kind of light elastic metamaterial (EM) shafts architecture comprised of a radial double-period element periodically as locally resonant oscillators with low frequency property. The dispersion relations are calculated by a method combining the transfer matrix and a lumped-mass method. The theoretical results agree well with finite method simulations, independent of the density of the hard material ring. The effects of the material parameters on the band gaps are further explored numerically. Our results show that in contrast to the traditional EM shaft, the weight of our proposed EM shaft can be reduced by 27% in the same band gap range while the vibration attenuation is kept unchanged, which is very convenient to instruct the potential engineering applications. Finally, the band edge frequencies of the lower band gaps for this light EM shaft are expressed analytically using physical heuristic models.

  13. The band system of ethane around 7 micron: Frequency analysis of the ν6 band

    Science.gov (United States)

    Moazzen-Ahmadi, N.; Oliaee, J. Norooz

    2016-09-01

    High quality line parameters of the band systems of ethane are required for accurate characterization of spectral features observed in the atmospheres of Jovian planets and their satellites. To date, experimental characterization of the excited vibrational states lying below 1300 cm-1 has been made. This includes the torsional bands around 35 μm, ν9 (820 cm-1), ν3 (990 cm-1), ν12-ν9 (380 cm-1) and ν9+ν4-ν4 (830 cm-1) bands. These earlier high resolution ro-vibrational analyses were made to experimental accuracy. Here, we report a detailed analysis of the weak ν6 band in the 1340-1410 cm-1 region using a spectrum recorded at a resolution of 0.003 cm-1 and temperature of 200 K. The Hamiltonian model included couplings between ν6 and ν9 (in particular with ν9+2ν4 with which it is resonantly coupled) as well as couplings between ν6 and ν8. An excellent fit to within experimental accuracy was obtained. Taking the results of this 5-state fit, together with earlier results on lower lying vibrations, we now have experimental characterization for torsion-vibration states of ethane lying below 1400 cm-1.

  14. Beta-carotene supplementation in smokers reduces the frequency of micronuclei in sputum.

    OpenAIRE

    Poppel, G. van; Kok, F. J.; Hermus, R. J.

    1992-01-01

    beta-carotene has been hypothesised to reduce lung cancer risk. We studied the effect of 14 weeks of beta-carotene supplementation (20 mg d-1) on the frequency of micronuclei in sputum in 114 heavy smokers in a double-blind trial. Micronuclei reflect DNA damage in exfoliated cells and may thus provide a marker of early-stage carcinogenesis. Pre-treatment blood levels of cotinine, beta-carotene, retinol and vitamins C and E were similar in the placebo group (n = 61) and the treatment group (n ...

  15. New space research frequency band proposals in the 20- to 40.5-GHz range

    Science.gov (United States)

    Bishop, D. F.

    1991-01-01

    Future space research communications systems may require spectra above 20 GHz. Frequency bands above 20 GHz are identified that are suitable for space research. The selection of the proper bands depends on consideration of interference with other radio services, adequate bandwidths, link performance, and technical requirements for practical implementation.

  16. Editorial Perspective: How to optimise frequency band neurofeedback for ADHD.

    Science.gov (United States)

    Bluschke, Annet; Roessner, Veit; Beste, Christian

    2016-04-01

    Attention deficit/hyperactivity disorder (ADHD) is one of the most prevalent paediatric neuropsychiatric disorders and is characterised by hyperactivity, inattention and increased impulsivity. Children with ADHD are often also characterised by deficits in a variety of cognitive domains, including problems in working memory, a generally slower and more variable style of information processing and deficits in temporal processing, inhibitory functions and delay processing. Overarching executive functions like information updating, response inhibition and mental set shifting are also impaired in many, but not all, children with ADHD, demonstrating the neuropsychological heterogeneity characterising this disorder. Deficits in executive functions can persist into adulthood and have a substantial negative impact on everyday life. A variety of approaches are commonly considered for the treatment of ADHD (including pharmacological interventions, patient-centred cognitive-behavioural therapy approaches and specific teacher/parent training programmes). More recently, adding to this multimodal treatment approach, neurofeedback has grown in popularity as an intervention option for patients with ADHD. This article considers this intervention approach and the opportunities for optimising treatment for executive control dysfunctions in ADHD using theta/beta neurofeedback. PMID:26968314

  17. WIDE BAND DUAL FREQUENCY CIRCULAR SLOT ANTEENA WITH RECTANGULAR STUB AT X AND KU BAND

    Directory of Open Access Journals (Sweden)

    R. Sanyal

    2013-03-01

    Full Text Available The paper presents design and study of the performance of simple circular slot antenna, fed by microstrip line. The dual frequency response having center frequency of 10.58 GHz is observed by using 0.2m.m wide rectangular stub connected with microstrip line. The effect of bandwidth enhancement studies on the return loss performance (-10db by changing the substrate thickness and substrate material is also being carried out.

  18. Activation of band 3 mediates group A Streptococcus streptolysin S-based beta-haemolysis.

    Science.gov (United States)

    Higashi, Dustin L; Biais, Nicolas; Donahue, Deborah L; Mayfield, Jeffrey A; Tessier, Charles R; Rodriguez, Kevin; Ashfeld, Brandon L; Luchetti, Jeffrey; Ploplis, Victoria A; Castellino, Francis J; Lee, Shaun W

    2016-01-01

    Streptococcus pyogenes, or group A Streptococcus (GAS), is a human bacterial pathogen that can manifest as a range of diseases from pharyngitis and impetigo to severe outcomes such as necrotizing fasciitis and toxic shock syndrome. GAS disease remains a global health burden with cases estimated at over 700 million annually and over half a million deaths due to severe infections(1). For over 100 years, a clinical hallmark of diagnosis has been the appearance of complete (beta) haemolysis when grown in the presence of blood. This activity is due to the production of a small peptide toxin by GAS known as streptolysin S. Although it has been widely held that streptolysin S exerts its lytic activity through membrane disruption, its exact mode of action has remained unknown. Here, we show, using high-resolution live cell imaging, that streptolysin S induces a dramatic osmotic change in red blood cells, leading to cell lysis. This osmotic change was characterized by the rapid influx of Cl(-) ions into the red blood cells through SLS-mediated disruption of the major erythrocyte anion exchange protein, band 3. Chemical inhibition of band 3 function significantly reduced the haemolytic activity of streptolysin S, and dramatically reduced the pathology in an in vivo skin model of GAS infection. These results provide key insights into the mechanism of streptolysin S-mediated haemolysis and have implications for the development of treatments against GAS. PMID:27571972

  19. Multi-frequency resonator based on dual-band S-shaped left-handed material.

    Science.gov (United States)

    Wang, Dongxing; Ran, Lixin; Wu, Bae-Ian; Chen, Hongsheng; Huangfu, Jiangtao; Grzegorczyk, Tomasz M; Kong, J A

    2006-12-11

    In this paper, we experimentally realize a one-dimensional RHM (Right-handed Material)-LHM (Left-handed Material) multi-frequency resonator that consists of a dual-negative-band LHM and air arranged in an X-band waveguide. Multi-resonant frequencies are observed within two left-handed bands of the LHM. The effects of the loss and the hyperbolic dispersion relation of LHM layer are discussed. The incorporation of such a LHM into the resonator design allows more flexibility to realize multi-resonance. PMID:19529656

  20. DC feedback for wide band frequency fixed current source

    Directory of Open Access Journals (Sweden)

    Aoday Hashim Mohamad Al-Rawi

    2013-03-01

    Full Text Available Alternating current sources are mainly used in bioelectrical impedance devices. Nowadays 50 – 100 kHz bioelectrical impedance devices are commonly used for body composition analysis. High frequency bioelectrical impedance analysis devices are mostly used in bioimpedance tomography and blood analysis. High speed op-amps and voltage comparators are used in this circuit. Direct current feedback is used to prevent delay. An N-Channel J-FET transistor was used to establish the voltage controlled gain amplifier (VCG. A sine wave signal has been applied as input voltage. The value of this signal should be constant in 170 mV rms to keep the output current in about 1 mA rms. Four frequencies; 100 kHz, 1 MHz, 2 MHz and 3.2 MHz were applied to the circuit and the current was measured for different load resistances. The results showed that the current was stable for changes in the resistor load, bouncing around an average point as a result of bouncing DC feedback.

  1. Acupuncture induces divergent alterations of functional connectivity within conventional frequency bands: evidence from MEG recordings.

    Directory of Open Access Journals (Sweden)

    Youbo You

    Full Text Available As an ancient Chinese healing modality which has gained increasing popularity in modern society, acupuncture involves stimulation with fine needles inserted into acupoints. Both traditional literature and clinical data indicated that modulation effects largely depend on specific designated acupoints. However, scientific representations of acupoint specificity remain controversial. In the present study, considering the new findings on the sustained effects of acupuncture and its time-varied temporal characteristics, we employed an electrophysiological imaging modality namely magnetoencephalography with a temporal resolution on the order of milliseconds. Taken into account the differential band-limited signal modulations induced by acupuncture, we sought to explore whether or not stimulation at Stomach Meridian 36 (ST36 and a nearby non-meridian point (NAP would evoke divergent functional connectivity alterations within delta, theta, alpha, beta and gamma bands. Whole-head scanning was performed on 28 healthy participants during an eyes-closed no-task condition both preceding and following acupuncture. Data analysis involved calculation of band-limited power (BLP followed by pair-wise BLP correlations. Further averaging was conducted to obtain local and remote connectivity. Statistical analyses revealed the increased connection degree of the left temporal cortex within delta (0.5-4 Hz, beta (13-30 Hz and gamma (30-48 Hz bands following verum acupuncture. Moreover, we not only validated the closer linkage of the left temporal cortex with the prefrontal and frontal cortices, but further pinpointed that such patterns were more extensively distributed in the ST36 group in the delta and beta bands compared to the restriction only to the delta band for NAP. Psychophysical results for significant pain threshold elevation further confirmed the analgesic effect of acupuncture at ST36. In conclusion, our findings may provide a new perspective to lend

  2. Determination of the optimal set of frequency bands for the PLANCK CMBR satellite mission

    DEFF Research Database (Denmark)

    Linden-Vornle, M.J.D.; Nørgaard-Nielsen, Hans Ulrik

    1998-01-01

    as discussed by Brendt et al. (1994). We have applied the model calculations to different mission configurations in order to determine the optimal combination of frequency bands. It is shown that only a large frequency coverage allows a sufficiently accurate separation of CMBR anisotropies and foreground...

  3. Design of a Symmetrical Microstrip Bandpass Filter for S-Band Frequency Range

    OpenAIRE

    Mohd F. Ain; Mandeep S.J. Singh; Prabhu; Syed I. S. Hassan

    2007-01-01

    A new type of microstrip bandpass filter is presented with a center frequency operation at 2.5GHz which lies in the S-band frequency range. The filter is designed to be much smaller compared to the same type of parallel-coupled bandpass filter. The simulation results are excellent and the filter is suitable for integration within various microwave subsystems.

  4. Effects of weak nonlinearity on dispersion relations and frequency band-gaps of periodic structures

    DEFF Research Database (Denmark)

    Sorokin, Vladislav; Thomsen, Jon Juel

    2015-01-01

    The analysis of the behaviour of linear periodic structures can be traced back over 300 years, to Sir Isaac Newton, and still attracts much attention. An essential feature of periodic struc-tures is the presence of frequency band-gaps, i.e. frequency ranges in which waves cannot propagate...

  5. Beat-induced fluctuations in auditory cortical beta-band activity: Using EEG to measure age-related changes

    Directory of Open Access Journals (Sweden)

    Laura K Cirelli

    2014-07-01

    Full Text Available People readily extract regularity in rhythmic auditory patterns, enabling prediction of the onset of the next beat. Recent magnetoencephalography (MEG research suggests that such prediction is reflected by the entrainment of oscillatory networks in the brain to the tempo of the sequence. In particular, induced beta-band oscillatory activity from auditory cortex decreases after each beat onset and rebounds prior to the onset of the next beat across tempi in a predictive manner. The objective of the present study was to examine the development of such oscillatory activity by comparing electroencephalography (EEG measures of beta-band fluctuations in 7-year-old children to adults. EEG was recorded while participants listened passively to isochronous tone sequences at three tempi (390, 585, and 780ms for onset-to-onset interval. In adults, induced power in the high beta-band (20-25 Hz decreased after each tone onset and rebounded prior to the onset of the next tone across tempo conditions, consistent with MEG findings. In children, a similar pattern was measured in the two slower tempo conditions, but was weaker in the fastest condition. The results indicate that the beta-band timing network works similarly in children, although there are age-related changes in consistency and the tempo range over which it operates.

  6. Frequency of hypothyroidism in patients of beta-thalassaemia

    International Nuclear Information System (INIS)

    To determine the frequency of hypothyroidism in patients suffering from homozygous-thalassaemia. This descriptive study included 70 diagnosed thalassaemia major patients aged 5-14 years. Demographic data as well as history of blood transfusion and chelation therapy was collected. Random blood samples were drawn and thyroid profile (serum thyroxine [T4], triiodothyronine [T3] and thyroid stimulating hormone concentrations [TSH]) was done by enzyme-linked immunosorbent assay (ELISA). Primary hypothyroidism was defined by a TSH level >4 macro IU/ml. Results were analysed by descriptive statistical methods. Primary hypothyroidism was seen in 18 (25.7%) patients. Of these, 17 had normal T4 levels with elevated TSH levels consistent with a diagnosis of compensated primary hypothyroidism whereas only one patient showed a decreased T4 level with elevated TSH (uncompensated primary hypothyroidism). Mean age of hypothyroid patients was 9.2 +- 2.6 years. Frequency of hypothyroidism was associated with increased serum ferritin levels. Primary hypothyroidism occurs in a significant proportion of thalassaemia major patients in the absence of obvious clinical signs of hypothyroidism. Regular follow-up for early detection and timely treatment of such complications could improve the quality of life of these patients (JPMA 60:17; 2010). (author)

  7. Atmospheric and Fog Effects on Ultra-Wide Band Radar Operating at Extremely High Frequencies

    Directory of Open Access Journals (Sweden)

    Nezah Balal

    2016-05-01

    Full Text Available The wide band at extremely high frequencies (EHF above 30 GHz is applicable for high resolution directive radars, resolving the lack of free frequency bands within the lower part of the electromagnetic spectrum. Utilization of ultra-wideband signals in this EHF band is of interest, since it covers a relatively large spectrum, which is free of users, resulting in better resolution in both the longitudinal and transverse dimensions. Noting that frequencies in the millimeter band are subjected to high atmospheric attenuation and dispersion effects, a study of the degradation in the accuracy and resolution is presented. The fact that solid-state millimeter and sub-millimeter radiation sources are producing low power, the method of continuous-wave wideband frequency modulation becomes the natural technique for remote sensing and detection. Millimeter wave radars are used as complementary sensors for the detection of small radar cross-section objects under bad weather conditions, when small objects cannot be seen by optical cameras and infrared detectors. Theoretical analysis for the propagation of a wide “chirped” Frequency-Modulated Continuous-Wave (FMCW radar signal in a dielectric medium is presented. It is shown that the frequency-dependent (complex refractivity of the atmospheric medium causes distortions in the phase of the reflected signal, introducing noticeable errors in the longitudinal distance estimations, and at some frequencies may also degrade the resolution.

  8. Atmospheric and Fog Effects on Ultra-Wide Band Radar Operating at Extremely High Frequencies.

    Science.gov (United States)

    Balal, Nezah; Pinhasi, Gad A; Pinhasi, Yosef

    2016-01-01

    The wide band at extremely high frequencies (EHF) above 30 GHz is applicable for high resolution directive radars, resolving the lack of free frequency bands within the lower part of the electromagnetic spectrum. Utilization of ultra-wideband signals in this EHF band is of interest, since it covers a relatively large spectrum, which is free of users, resulting in better resolution in both the longitudinal and transverse dimensions. Noting that frequencies in the millimeter band are subjected to high atmospheric attenuation and dispersion effects, a study of the degradation in the accuracy and resolution is presented. The fact that solid-state millimeter and sub-millimeter radiation sources are producing low power, the method of continuous-wave wideband frequency modulation becomes the natural technique for remote sensing and detection. Millimeter wave radars are used as complementary sensors for the detection of small radar cross-section objects under bad weather conditions, when small objects cannot be seen by optical cameras and infrared detectors. Theoretical analysis for the propagation of a wide "chirped" Frequency-Modulated Continuous-Wave (FMCW) radar signal in a dielectric medium is presented. It is shown that the frequency-dependent (complex) refractivity of the atmospheric medium causes distortions in the phase of the reflected signal, introducing noticeable errors in the longitudinal distance estimations, and at some frequencies may also degrade the resolution. PMID:27223286

  9. Ultrawide low frequency band gap of phononic crystal in nacreous composite material

    Energy Technology Data Exchange (ETDEWEB)

    Yin, J.; Huang, J.; Zhang, S., E-mail: zhangs@dlut.edu.cn; Zhang, H.W.; Chen, B.S.

    2014-06-27

    The band structure of a nacreous composite material is studied by two proposed models, where an ultrawide low frequency band gap is observed. The first model (tension-shear chain model) with two phases including brick and mortar is investigated to describe the wave propagation in the nacreous composite material, and the dispersion relation is calculated by transfer matrix method and Bloch theorem. The results show that the frequency ranges of the pass bands are quite narrow, because a special tension-shear chain motion in the nacreous composite material is formed by some very slow modes. Furthermore, the second model (two-dimensional finite element model) is presented to investigate its band gap by a multi-level substructure scheme. Our findings will be of great value to the design and synthesis of vibration isolation materials in a wide and low frequency range. Finally, the transmission characteristics are calculated to verify the results. - Highlights: • A Brick-and-Mortar structure is used to discuss wave propagation through nacreous materials. • A 1D Bloch wave solution of nacreous materials with a tension-shear chain model is obtained. • The band structure and transmission characteristics of nacreous materials with the FE model are examined. • An ultrawide low frequency band gap is found in nacreous materials with both theory and FE model.

  10. Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

    Science.gov (United States)

    Simons, Rainee N.; Wintucky, Edwin G.

    2016-01-01

    This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

  11. Study of radio frequency interference effects on radiometry bands in urban environments

    OpenAIRE

    Forte Veliz, Giuseppe Francesco; Camps Carmona, Adriano José; Tarongí Bauzá, José Miguel; Vall-Llossera Ferran, Mercedes Magdalena

    2012-01-01

    Microwave radiometers are very accurate passive sensors that have been successfully used in Earth remote sensing during the last decades. Microwave radiometers measure thermal noise, therefore any other signal (radio-frequency interference or RFI) present in the band modifies the value of the measured power, and the corresponding estimated antenna temperature, from which the geophysical parameters will be retrieved. An on-going RFI survey shows how corrupted is the spectrum “protected” L-band...

  12. Behaviour of spectral entropy, spectral edge frequency 90%, and alpha and beta power parameters during low-dose propofol infusion.

    LENUS (Irish Health Repository)

    Mahon, P

    2012-02-03

    BACKGROUND: In this study we analyse the behaviour, potential clinical application and optimal cortical sampling location of the spectral parameters: (i) relative alpha and beta power; (ii) spectral edge frequency 90%; and (iii) spectral entropy as monitors of moderate propofol-induced sedation. METHODS: Multi-channel EEG recorded from 12 ASA 1 (American Society of Anesthesiologists physical status 1) patients during low-dose, target effect-site controlled propofol infusion was used for this analysis. The initial target effect-site concentration was 0.5 microg ml(-1) and increased at 4 min intervals in increments of 0.5 to 2 microg ml(-1). EEG parameters were calculated for 2 s epochs in the frequency ranges 0.5-32 and 0.5-47 Hz. All parameters were calculated in the channels: P4-O2, P3-O1, F4-C4, F3-C3, F3-F4, and Fp1-Fp2. Sedation was assessed clinically using the OAA\\/S (observer\\'s assessment of alertness\\/sedation) scale. RESULTS: Relative beta power and spectral entropy increased with increasing propofol effect-site concentration in both the 0.5-47 Hz [F(18, 90) = 3.455, P<0.05 and F(18, 90) = 3.33, P<0.05, respectively] and 0.5-32 Hz frequency range. This effect was significant in each individual channel (P<0.05). No effect was seen of increasing effect-site concentration on relative power in the alpha band. Averaged across all channels, spectral entropy did not outperform relative beta power in either the 0.5-32 Hz [Pk=0.79 vs 0.814 (P>0.05)] or 0.5-47 Hz range [Pk=0.81 vs 0.82 (P>0.05)]. The best performing indicator in any single channel was spectral entropy in the frequency range 0.5-47 Hz in the frontal channel F3-F4 (Pk=0.85). CONCLUSIONS: Relative beta power and spectral entropy when considered over the propofol effect-site range studied here increase in value, and correlate well with clinical assessment of sedation.

  13. Dual-band and high-efficiency polarization converter based on metasurfaces at microwave frequencies

    Science.gov (United States)

    Liu, Yajun; Xia, Song; Shi, Hongyu; Zhang, Anxue; Xu, Zhuo

    2016-06-01

    We present a dual-band and high-efficiency polarization converter in microwave regime. The proposed converter can convert a linearly polarized wave to its cross-polarized wave for two distinct bands: Ku (11.5-20.0 GHz) and Ka (28.8-34.0 GHz). It can also convert the linearly polarized wave to a circularly polarized wave at four other frequencies. The experimental results are in good agreement with simulation results for both frequency bands. The polarization conversion ratio is above 0.94 for the Ku-band and 0.90 for the Ka-band. Furthermore, the converter can achieve dual-band and high-efficiency polarization conversion over angles of incidence up to 45°. The converter is also polarization-selective in that only the x- and y-polarized waves can be converted. The physical mechanism of the dual-band polarization conversion effect is interpreted via decomposed electric field components that couple with different plasmon resonance modes of the structure.

  14. Dual-etalon cavity ring-down frequency-comb spectroscopy with broad band light source

    Science.gov (United States)

    Chandler, David W; Strecker, Kevin E

    2014-04-01

    In an embodiment, a dual-etalon cavity-ring-down frequency-comb spectrometer system is described. A broad band light source is split into two beams. One beam travels through a first etalon and a sample under test, while the other beam travels through a second etalon, and the two beams are recombined onto a single detector. If the free spectral ranges ("FSR") of the two etalons are not identical, the interference pattern at the detector will consist of a series of beat frequencies. By monitoring these beat frequencies, optical frequencies where light is absorbed may be determined.

  15. NASA Standard Initiator Susceptibility to UHF and S-Band Radio Frequency Power and Lightning Strikes

    Science.gov (United States)

    Burnham, Karen; Scully, Robert; Norgard, John

    2013-01-01

    The NASA Standard Initiator (NSI) is an important piece of pyrotechnic equipment used in many space applications. This presentation will outline the results of a series of tests done at UHF and S-Band frequencies to determine NSI susceptibility to Radio Frequency (RF) power. The results show significant susceptibility to pulsed RF power in the S-Band region. Additional testing with lightning pulses injected into the firing line harness, modelling the indirect effects of a lightning strike to a spacecraft, showed no vulnerability

  16. Polarization and angle insensitive dual-band bandpass frequency selective surface using all-dielectric metamaterials

    Science.gov (United States)

    Yu, Fei; Wang, Jun; Wang, Jiafu; Ma, Hua; Du, Hongliang; Xu, Zhuo; Qu, Shaobo

    2016-04-01

    In this paper, we demonstrate a dual-band bandpass all-dielectric frequency selective surface (FSS), the building elements of which are high-permittivity ceramic particles rather than metallic patterns. With proper structural design and parameter adjustment, the resonant frequency can be tuned at will. Dual-band bandpass response can be realized due to the coupling between electric and magnetic resonances. As an example, a dual-band bandpass FSS is designed in Ku band, which is composed of two-dimensional periodic arrays of complementary quatrefoil structures (CQS) cut from dielectric plates. Moreover, cylindrical dielectric resonators are introduced and placed in the center of each CQS to broaden the bandwidth and to sharpen the cut-off frequency. Theoretical analysis shows that the bandpass response arises from impedance matching caused by electric and magnetic resonances. In addition, effective electromagnetic parameters and dynamic field distributions are presented to explain the mechanism of impedance matching. The proposed FSS has the merits of polarization independence, stable transmission, and sharp roll-off frequency. The method can also be used to design all-dielectric FSSs with continuum structures at other frequencies.

  17. Odd-frequency Cooper pairs in two-band superconductors and their magnetic response

    Science.gov (United States)

    Asano, Yasuhiro; Sasaki, Akihiro

    2015-12-01

    We discuss the appearance of odd-frequency Cooper pairs in two-band superconductors by solving the Gor'kov equation analytically. We introduce the equal-time s -wave pair potentials as realized in MgB2 and iron pnictides. Although the order parameter symmetry is conventional, the band degree of freedom enriches the symmetry variety of pairing correlations. The hybridization and the asymmetry between the two conduction bands induce odd-frequency pairs as a subdominant pairing correlation in the uniform ground state. To study the magnetic response of odd-frequency Cooper pairs, we analyze the Meissner kernel represented by the Gor'kov Green function. In contrast to the even-frequency pairs linked to the pair potential, the induced odd-frequency Cooper pairs indicate a paramagnetic property. We also discuss the relation between the amplitude of the odd-frequency pairing correlation and the stability of superconducting states in terms of the self-consistent equation for the pair potential.

  18. Circularly Polarized S Band Dual Frequency Square Patch Antenna Using Glass Microfiber Reinforced PTFE Composite

    Directory of Open Access Journals (Sweden)

    M. Samsuzzaman

    2014-01-01

    Full Text Available Circularly polarized (CP dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the desired operating band. The experimental results show that the impedance bandwidth is approximately 30 MHz (2.16 GHz to 2.19 GHz for lower band and 40 MHz (3.29 GHz to 3.33 GHz for higher band with an average peak gain of 6.59 dBiC and 5.52 dBiC, respectively. Several optimizations are performed to obtain the values of the antenna physical parameters. Moreover, the proposed antenna possesses compactness, light weight, simplicity, low cost, and circularly polarized. It is an attractive candidate for dual band satellite antennas where lower band can be used for uplink and upper band can be used for downlink.

  19. Circularly polarized S band dual frequency square patch antenna using glass microfiber reinforced PTFE composite.

    Science.gov (United States)

    Samsuzzaman, M; Islam, M T; Arshad, Haslina; Mandeep, J S; Misran, N

    2014-01-01

    Circularly polarized (CP) dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE) composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the desired operating band. The experimental results show that the impedance bandwidth is approximately 30 MHz (2.16 GHz to 2.19 GHz) for lower band and 40 MHz (3.29 GHz to 3.33 GHz) for higher band with an average peak gain of 6.59 dBiC and 5.52 dBiC, respectively. Several optimizations are performed to obtain the values of the antenna physical parameters. Moreover, the proposed antenna possesses compactness, light weight, simplicity, low cost, and circularly polarized. It is an attractive candidate for dual band satellite antennas where lower band can be used for uplink and upper band can be used for downlink. PMID:24982943

  20. Correlation Coefficient Control For A Frequency Reconfigurable Dual-Band Compact MIMO Antenna Destined For LTE

    DEFF Research Database (Denmark)

    Tatomirescu, Alexandru; Buskgaard, Emil Feldborg; Pedersen, Gert Frølund

    2014-01-01

    In this contribution, we are proposing a compact design for an implementation of a two element MIMO antenna destined for LTE smart phones. The antennas are collocated at one end of the PCB to minimize antenna volume. Each element is dual-band and frequency reconfigurable using tunable capacitors...

  1. Integrated Common Radio Resource Management with Spectrum Aggregation over Non-Contiguous Frequency Bands

    DEFF Research Database (Denmark)

    Cabral, Orlando; Meucci, Filippo; Mihovska, Albena D.;

    2011-01-01

    This paper proposes an integrated Common Radio Resource Management (iCRRM). The iCRRM performs classic CRRM functionalities jointly with Spectrum Aggregation (SA), being able to switch users between non-contiguous frequency bands. The SA scheduling is obtained with an optimised General Multi...

  2. Tuning Range Optimization of a Planar Inverted F Antenna for LTE Low Frequency Bands

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pelosi, Mauro; Franek, Ondrej;

    2011-01-01

    This paper presents a Planar Inverted F Antenna (PIFA) tuned with a fixed capacitor to the low frequency bands supported by the Long Term Evolution (LTE) technology. The tuning range is investigated and optimized with respect to the bandwidth and the efficiency of the resulting antenna. Simulations...

  3. Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR

    Science.gov (United States)

    Pilia, M.; Hessels, J. W. T.; Stappers, B. W.; Kondratiev, V. I.; Kramer, M.; van Leeuwen, J.; Weltevrede, P.; Lyne, A. G.; Zagkouris, K.; Hassall, T. E.; Bilous, A. V.; Breton, R. P.; Falcke, H.; Grießmeier, J.-M.; Keane, E.; Karastergiou, A.; Kuniyoshi, M.; Noutsos, A.; Osłowski, S.; Serylak, M.; Sobey, C.; ter Veen, S.; Alexov, A.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Bîrzan, L.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brüggen, M.; Ciardi, B.; Corbel, S.; de Geus, E.; de Jong, A.; Deller, A.; Duscha, S.; Eislöffel, J.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Gunst, A. W.; Hamaker, J. P.; Heald, G.; Horneffer, A.; Jonker, P.; Juette, E.; Kuper, G.; Maat, P.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Miller-Jones, J. C. A.; Nelles, A.; Paas, H.; Pandey-Pommier, M.; Pietka, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H.; Rowlinson, A.; Schwarz, D.; Smirnov, O.; Steinmetz, M.; Stewart, A.; Swinbank, J. D.; Tagger, M.; Tang, Y.; Tasse, C.; Thoudam, S.; Toribio, M. C.; van der Horst, A. J.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijers, R. A. M. J.; Wijnands, R.; Wijnholds, S. J.; Wucknitz, O.; Zarka, P.

    2016-02-01

    Context. LOFAR offers the unique capability of observing pulsars across the 10-240 MHz frequency range with a fractional bandwidth of roughly 50%. This spectral range is well suited for studying the frequency evolution of pulse profile morphology caused by both intrinsic and extrinsic effects such as changing emission altitude in the pulsar magnetosphere or scatter broadening by the interstellar medium, respectively. Aims: The magnitude of most of these effects increases rapidly towards low frequencies. LOFAR can thus address a number of open questions about the nature of radio pulsar emission and its propagation through the interstellar medium. Methods: We present the average pulse profiles of 100 pulsars observed in the two LOFAR frequency bands: high band (120-167 MHz, 100 profiles) and low band (15-62 MHz, 26 profiles). We compare them with Westerbork Synthesis Radio Telescope (WSRT) and Lovell Telescope observations at higher frequencies (350 and 1400 MHz) to study the profile evolution. The profiles were aligned in absolute phase by folding with a new set of timing solutions from the Lovell Telescope, which we present along with precise dispersion measures obtained with LOFAR. Results: We find that the profile evolution with decreasing radio frequency does not follow a specific trend; depending on the geometry of the pulsar, new components can enter into or be hidden from view. Nonetheless, in general our observations confirm the widening of pulsar profiles at low frequencies, as expected from radius-to-frequency mapping or birefringence theories. We offer this catalogue of low-frequency pulsar profiles in a user friendly way via the EPN Database of Pulsar Profiles, http://www.epta.eu.org/epndb/

  4. Multi-band local microwave signal generation based on an optical frequency comb generator

    Science.gov (United States)

    Wang, Wen Ting; Liu, Jian Guo; Sun, Wen Hui; Chen, Wei; Zhu, Ning Hua

    2015-03-01

    We propose and experimental demonstrate a new method to generate multi-band local microwave signals based on an optical frequency comb generator (OFCG) by applying an optical sideband injection locking technique and an optical heterodyning technique. The generated microwave signal can cover multi bands from S band to Ka band. A tunable multiband microwave signal spanning from 5 GHz to 40 GHz can be generated by the beating between the optical carrier and injection locked modulation sidebands in a photodetector without an optical filter. The wavelength of the slave laser can be continuously and near-linearly adjusted by proper changing its bias current. By tuning the bias current of the slave laser, the wavelength of that is matched to one of the modulation sidebands of the OFCG. The performance of the arrangement in terms of the tunability and stability of the generated microwave signal is also studied.

  5. Frequency of the Group A Beta Hemolytic Streptococcus Infection in Children Presenting with Acute Tonsillopharyngitis

    OpenAIRE

    Özgül Yiğit; Nevin Cambaz; Emin Özkaya; Yeşim Coşkun; Nedim Samancı; Elif Ünver; Betül Sezgin

    2009-01-01

    Aim: The aim of this study was to evaluate the frequency of group A beta hemolytic streptococcus (GABHS) in children with tonsillopharyngitis and to assess their complaints and clinical findings.Materials and Method: A total of 420 children who presented to our outpatient department with acute tonsillopharyngitis were enrolled to the study. The clinical features of patients with positive throat cultures for GABHS were compared to those with negative culture results. Presence of fever (≥37.50C...

  6. A wide-band tunable phase shifter for radio-frequency reflectometry

    CERN Document Server

    Yin, G; Laird, E A

    2014-01-01

    Radio-frequency reflectometry of nanodevices requires careful separation of signal quadratures to distinguish dissipative and dispersive contributions to the device impedance. A tunable phase shifter for this purpose is described and characterized. The phase shifter, consisting of a varactor-loaded transmission line, has the necessary tuning range combined with acceptable insertion loss across a frequency band 100 MHz - 1 GHz spanning most radio-frequency experiments. Its operation is demonstrated by demodulating separately the signals due to resistance and capacitance changes in a model device.

  7. Wide-Band, Low-Frequency Pulse Profiles of 100 Radio Pulsars with LOFAR

    CERN Document Server

    Pilia, M; Stappers, B W; Kondratiev, V I; Kramer, M; van Leeuwen, J; Weltevrede, P; Lyne, A G; Zagkouris, K; Hassall, T E; Bilous, A V; Breton, R P; Falcke, H; Grießmeier, J -M; Keane, E; Karastergiou, A; Kuniyoshi, M; Noutsos, A; Osłowski, S; Serylak, M; Sobey, C; ter Veen, S; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Bell, M E; Bentum, M J; Bernardi, G; Bîrzan, L; Bonafede, A; Breitling, F; Broderick, J W; Brüggen, M; Ciardi, B; Corbel, S; de Geus, E; de Jong, A; Deller, A; Duscha, S; Eislöffel, J; Fallows, R A; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; Gunst, A W; Hamaker, J P; Heald, G; Horneffer, A; Jonker, P; Juette, E; Kuper, G; Maat, P; Mann, G; Markoff, S; McFadden, R; McKay-Bukowski, D; Miller-Jones, J C A; Nelles, A; Paas, H; Pandey-Pommier, M; Pietka, M; Pizzo, R; Polatidis, A G; Reich, W; Röttgering, H; Rowlinson, A; Schwarz, D; Smirnov, O; Steinmetz, M; Stewart, A; Swinbank, J D; Tagger, M; Tang, Y; Tasse, C; Thoudam, S; Toribio, M C; van der Horst, A J; Vermeulen, R; Vocks, C; van Weeren, R J; Wijers, R A M J; Wijnands, R; Wijnholds, S J; Wucknitz, O; Zarka, P

    2015-01-01

    LOFAR offers the unique capability of observing pulsars across the 10-240 MHz frequency range with a fractional bandwidth of roughly 50%. This spectral range is well-suited for studying the frequency evolution of pulse profile morphology caused by both intrinsic and extrinsic effects: such as changing emission altitude in the pulsar magnetosphere or scatter broadening by the interstellar medium, respectively. The magnitude of most of these effects increases rapidly towards low frequencies. LOFAR can thus address a number of open questions about the nature of radio pulsar emission and its propagation through the interstellar medium. We present the average pulse profiles of 100 pulsars observed in the two LOFAR frequency bands: High Band (120-167 MHz, 100 profiles) and Low Band (15-62 MHz, 26 profiles). We compare them with Westerbork Synthesis Radio Telescope (WSRT) and Lovell Telescope observations at higher frequencies (350 and1400 MHz) in order to study the profile evolution. The profiles are aligned in abs...

  8. Effects of corrugation shape on frequency band-gaps for longitudinal wave motion in a periodic elastic layer

    DEFF Research Database (Denmark)

    Sorokin, Vladislav

    2016-01-01

    The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band-gaps are det......The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band......, harmonic in the corrugation series. The revealed insights into the mechanism of band-gap formation can be used to predict locations and widths of all frequency band-gaps featured by any corrugation shape. These insights are general and can be valid also for other types of wave motion in periodic structures......, e.g., transverse or torsional vibration....

  9. Temporal-envelope constancy of speech in rooms and the perceptual weighting of frequency bands.

    Science.gov (United States)

    Watkins, Anthony J; Raimond, Andrew P; Makin, Simon J

    2011-11-01

    Three experiments measured constancy in speech perception, using natural-speech messages or noise-band vocoder versions of them. The eight vocoder-bands had equally log-spaced center-frequencies and the shapes of corresponding "auditory" filters. Consequently, the bands had the temporal envelopes that arise in these auditory filters when the speech is played. The "sir" or "stir" test-words were distinguished by degrees of amplitude modulation, and played in the context; "next you'll get _ to click on." Listeners identified test-words appropriately, even in the vocoder conditions where the speech had a "noise-like" quality. Constancy was assessed by comparing the identification of test-words with low or high levels of room reflections across conditions where the context had either a low or a high level of reflections. Constancy was obtained with both the natural and the vocoded speech, indicating that the effect arises through temporal-envelope processing. Two further experiments assessed perceptual weighting of the different bands, both in the test word and in the context. The resulting weighting functions both increase monotonically with frequency, following the spectral characteristics of the test-word's [s]. It is suggested that these two weighting functions are similar because they both come about through the perceptual grouping of the test-word's bands. PMID:22087906

  10. Band Structure and Fermi-Surface Properties of Ordered beta-Brass

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Christensen, N. E.

    1973-01-01

    The band structure of ordered β-brass (β′-CuZn) has been calculated throughout the Brillouin zone by the augmented-plane-wave method. The present band model differs from previous calculations with respect to the position and width of the Cu 3d band. The derived dielectric function ε2(ω) and the p...

  11. A novel in-line frequency sensor based on coupling capacitance for X-band application

    International Nuclear Information System (INIS)

    This paper presents a novel in-line frequency sensor, based on coupling capacitance, for X-band applications. The novel frequency sensor can achieve absolute frequency measurement with a simple structure and no DC power consumption. Fabrication of the frequency sensor is completely compatible with the GaAs monolithic microwave integrated circuit process. A well-designed metal–insulator–metal capacitor is employed to couple a certain percentage of incident power and a thermoelectric power sensor is used to measure the coupled power. The sensor design is guided by HFSS simulation and a lumped circuit model. The results validate the effectiveness of the simulation and model, and show relatively good performance of the frequency sensor with simple and reliable components. The net sensitivity of the frequency sensor is about 1.43 mV (W•GHz)−1, and the measured S 11 and S 21 are better than  −14.8 dB and  −1.39 dB at X-band. (paper)

  12. Band-gap tunable dielectric elastomer filter for low frequency noise

    Science.gov (United States)

    Jia, Kun; Wang, Mian; Lu, Tongqing; Zhang, Jinhua; Wang, Tiejun

    2016-05-01

    In the last decades, diverse materials and technologies for sound insulation have been widely applied in engineering. However, suppressing the noise radiation at low frequency still remains a challenge. In this work, a novel membrane-type smart filter, consisting of a pre-stretched dielectric elastomer membrane with two compliant electrodes coated on the both sides, is presented to control the low frequency noise. Since the stiffness of membrane dominates its acoustic properties, sound transmission band-gap of the membrane filter can be tuned by adjusting the voltage applied to the membrane. The impedance tube experiments have been carried out to measure the sound transmission loss (STL) of the filters with different electrodes, membrane thickness and pre-stretch conditions. The experimental results show that the center frequency of sound transmission band-gap mainly depends on the stress in the dielectric elastomer, and a large band-gap shift (more than 60 Hz) can be achieved by tuning the voltage applied to the 85 mm diameter VHB4910 specimen with pre-stretch {λ }0=3. Based on the experimental results and the assumption that applied electric field is independent of the membrane behavior, 3D finite element analysis has also been conducted to calculate the membrane stress variation. The sound filter proposed herein may provide a promising facility to control low frequency noise source with tonal characteristics.

  13. Improved synthetic aperture focusing technique results of thick concrete specimens through frequency banding

    Science.gov (United States)

    Clayton, Dwight; Barker, Alan; Albright, Austin; Santos-Villalobos, Hector

    2016-02-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on ultrasonic data collected from thick, complex concrete structures such as in NPPs. Towards these goals, we apply the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band's interaction with the contents of the concrete structure. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To minimize artifacts caused by boundary effects, the dimensions of the specimens should not be too compact. In this paper, we apply this enhanced SAFT technique to a 2.134 m × 2.134 m × 1.016 m concrete

  14. Asteroseismology of the Beta Cephei star Nu Eridani: photometric observations and pulsational frequency analysis

    CERN Document Server

    Handler, G; Jerzykiewicz, M; Krisciunas, K; Tshenye, T; Rodríguez, E; Costa, V; Zhou, A Y; Medupe, R; Phorah, W M; Garrido, R; Amado, P J; Paparo, M; Zsuffa, D; Ramokgali, L; Crowe, R; Purves, N; Avila, R; Knight, R; Brassfield, E; Kilmartin, P M; Cottrell, P L

    2004-01-01

    We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our measurements shows that the variability of Nu Eri can be decomposed into 23 sinusoidal components, eight of which correspond to independent pulsation frequencies between 5 - 8 c/d. Some of these are arranged in multiplets, which suggests rotational m-mode splitting of nonradial pulsation modes as the cause. If so, the rotation period of the star must be between 30 - 60 d. One of the signals in the light curves of Nu Eri has a very low frequency of 0.432 c/d. It can be a high-order combination frequency or, more likely, an independent pulsation mode. In the latter case Nu Eri would be both a Beta Cephei star and a slowly pulsating B (SPB) star. The photometric amplitudes of the individual pulsation modes of Nu Eri appear to have increased by about 20 per cent over the last 40 y...

  15. Low-frequency waves in a high-beta collisionless plasma Polarization, compressibility and helicity

    Science.gov (United States)

    Gary, S. P.

    1986-01-01

    This paper considers the linear theory of waves near and below the ion cyclotron frequency in an isothermal electron-ion Vlasov plasma which is isotropic, homogeneous and magnetized. Numerical solutions of the full dispersion equation for the magnetosonic/whistler and Alfven/ion cyclotron modes at beta(i) = 1.0 are presented, and the polarizations, compressibilities, helicities, ion Alfven ratios and ion cross-helicities are exhibited and compared. At sufficiently large beta(i) and theta, the angle of propagation with respect to the magnetic field, the real part of the polarization of the Alfven/ion cyclotron wave changes sign, so that, for such parameters, this mode is no longer left-hand polarized. The Alfven/ion cyclotron mode becomes more compressive as the wavenumber increases, whereas the magnetosonic/whistler becomes more compressive with increasing theta.

  16. The Size-Frequency Distribution of the Zodiacal Cloud Evidence from the Solar System Dust Bands

    CERN Document Server

    Grogan, K; Durda, D D

    2000-01-01

    Recent observations of the size-frequency distribution of zodiacal cloud particles obtained from the cratering record on the LDEF satellite (Love and Brownlee 1993) reveal a significant large particle population (100 micron diameter or greater) near 1 AU. Our previous modeling of the Solar System dust bands (Grogan et al 1997), features of the zodiacal cloud associated with the comminution of Hirayama family asteroids, has been limited by the fact that only small particles (25 micron diameter or smaller) have been considered. This was due to the prohibitively large amount of computing power required to numerically analyze the dynamics of larger particles. The recent availability of cheap, fast processors has finally made this work possible. Models of the dust bands are created, built from individual dust particle orbits, taking into account a size-frequency distribution of the material and the dynamical history of the constituent particles. These models are able to match both the shapes and amplitudes of the ...

  17. Radiation Characteristic Improvement of X-Band Slot Antenna Using New Multiband Frequency-Selective Surface

    Directory of Open Access Journals (Sweden)

    Elham Moharamzadeh

    2014-01-01

    Full Text Available A new configuration of frequency-selective surfaces (FSSs is designed and presented with multiresonance characteristics which covers all of the frequency domain of X-band from 8 to 12 GHz. The proposed FSS comprises three conductor-based split ring resonators, connected together. In this design, two unit cells of the FSS with different lengths are employed side by side to design the FSS. The FSS is used to enhance the gain of the new designed triangle slot antenna at X-band. The proposed FSS is analyzed by using reflected-wave unit-cell box method. The single, double, and array of the FSS cells are studied. Next, the designed FSS along with the antenna is analyzed. The measurement and simulated results of the impedance and radiation characteristics, especially the increment of the gain, are presented.

  18. Microwave properties of Al and Mn doped nickel ferrites at Ku band frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Raju, K. [Department of Physics, Osmania University, Hyderabad-500 007, Andhra Pradesh (India); Balaji, C.G. [Research Centre Imarat, Vigyanakancha, Hyderabad-500 069 (India); Venugopal Reddy, P., E-mail: paduruvenugopalreddy@gmail.com [Department of Physics, Osmania University, Hyderabad-500 007, Andhra Pradesh (India)

    2014-03-15

    To investigate the influence of aluminum and manganese doping on structural, electrical, magnetic and microwave behavior of nickel ferrites, the samples were prepared by citrate sol–gel method. Samples were characterized by X-ray diffractometer using Rietveld refinement technique and are found to have cubic structure with space group Fd3{sup ¯}m. A systematic investigation of magnetization, permeability, permittivity and microwave properties such as isolation, insertion loss and return loss was undertaken at Ku band (12–18 GHz) frequencies. A qualitative explanation for the various observed phenomena was given. - Highlights: • Influence of aluminum and manganese doping on various properties of Nickel ferrite. • Isolation, insertion loss and return loss were undertaken at Ku band (12–18 GHz) frequencies. • Qualitative explanation for the various observed phenomena was given.

  19. Low-frequency band gaps in chains with attached non-linear oscillators

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard

    2007-01-01

    in structures with periodic or random inclusions are located mainly in the high frequency range, as the wavelength has to be comparable with the distance between the alternating parts. Band gaps may also exist in structures with locally attached oscillators. In the linear case the gap is located around......The aim of this article is to investigate the wave propagation in one-dimensional chains with attached non-linear local oscillators by using analytical and numerical models. The focus is on the influence of non-linearities on the filtering properties of the chain in the low frequency range...

  20. A dual-band quadrature VCO with gain proportional to oscillation frequency

    International Nuclear Information System (INIS)

    This paper presents a novel dual-band quadrature voltage controlled oscillator (VCO) with the gain proportional to the oscillation frequency. Frequency synthesizers with this VCO can reduce the bandwidth fluctuation over all the frequency ranges without compensation or calibration. Besides the original switched capacitor array, an extra switched varactor array is adopted for the implementation of the proposed VCO. The tuning technique of changing the values of the capacitor and varactor at the same ratio is also derived. For verification purposes, a 2.5 G/3.5 G dual-band quadrature VCO is fabricated in a 0.13 μm CMOS process for WiMAX applications. Measurement results show that the VCO gain is closely proportional to the oscillation frequency with ±16% variation over the entire frequency range. The phase noise is −138.15 dBc/Hz at 10 MHz from the 2.5 GHz carrier and −137.44 dBc/Hz at 10 MHz from the 3.5 GHz carrier. (semiconductor integrated circuits)

  1. A dual-band quadrature VCO with gain proportional to oscillation frequency

    Science.gov (United States)

    Wenrui, Zhu; Haigang, Yang; Tongqiang, Gao; Hui, Zhang

    2013-08-01

    This paper presents a novel dual-band quadrature voltage controlled oscillator (VCO) with the gain proportional to the oscillation frequency. Frequency synthesizers with this VCO can reduce the bandwidth fluctuation over all the frequency ranges without compensation or calibration. Besides the original switched capacitor array, an extra switched varactor array is adopted for the implementation of the proposed VCO. The tuning technique of changing the values of the capacitor and varactor at the same ratio is also derived. For verification purposes, a 2.5 G/3.5 G dual-band quadrature VCO is fabricated in a 0.13 μm CMOS process for WiMAX applications. Measurement results show that the VCO gain is closely proportional to the oscillation frequency with ±16% variation over the entire frequency range. The phase noise is -138.15 dBc/Hz at 10 MHz from the 2.5 GHz carrier and -137.44 dBc/Hz at 10 MHz from the 3.5 GHz carrier.

  2. NEURO FUZZY BASED PERFORMANCE ANALYSIS OF MULTIBAND ULTRA WIDE BAND ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM

    Directory of Open Access Journals (Sweden)

    G. Joselin Retna Kumar

    2014-01-01

    Full Text Available This study proposes an efficient channel-estimation scheme for Multiband (MB Orthogonal Frequency Division Multiplexing (OFDM-based Ultra Wide Band (UWB communication systems. One of the challenges in wireless system is the frequency selective fading caused due to multipath channel between the transmitter and receiver. The signal bandwidth in broad band cellular wireless systems typically exceeds the coherence bandwidth of the multipath channel. To overcome such a multipath fading environment with low complexity and to increase the performance, UWB OFDM system is used. To practically realize MB-OFDM UWB, one needs to cope with numerous design challenges, particularly in receiver designs such as symbol timing, Carrier Frequency Offset (CFO and sampling frequency offset compensation, as well as Channel Frequency Response (CFR estimation. A channel estimation scheme using a Takagi-Sugeno (T-S fuzzy based neural network under the time varying velocity of the mobile station in a UWB OFDM system is proposed in this study. In our proposal, by utilizing the learning capability of Adaptive Neuro-Fuzzy Inference System (ANFIS, the ANFIS is trained with correct channel state information then the trained network is used as a channel estimator. To validate the performance of our proposed method, simulation results are given and found that it gives more accurate prediction of channel coefficients as compared with fuzzy channel estimator under various highly noisy multipath channel conditions.

  3. Ka-band microwave frequency comb Doppler reflectometer system for the Large Helical Device

    International Nuclear Information System (INIS)

    A ka-band multi-channel Doppler reflectometer system was constructed for the Large Helical Device (LHD) using a comb frequency generator as a source. A filter bank system is utilized for precise quadrature phase detection, and preliminary back-scattered waves were obtained in LHD plasma experiments. In addition, a direct digital signal acquisition system was successfully demonstrated for providing a greater number of multi-channel measurements. (author)

  4. Short pulse equations and localized structures in frequency band gaps of nonlinear metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Tsitsas, N.L. [School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografos, Athens 15773 (Greece); Horikis, T.P. [Department of Mathematics, University of Ioannina, Ioannina 45110 (Greece); Shen, Y.; Kevrekidis, P.G.; Whitaker, N. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Frantzeskakis, D.J., E-mail: dfrantz@phys.uoa.g [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece)

    2010-03-01

    We consider short pulse propagation in nonlinear metamaterials characterized by a weak Kerr-type nonlinearity in their dielectric response. Two short-pulse equations (SPEs) are derived for the high- and low-frequency 'band gaps' (where linear electromagnetic waves are evanescent) with linear effective permittivity epsilon<0 and permeability mu>0. The structure of the solutions of the SPEs is also briefly discussed, and connections with the soliton solutions of the nonlinear Schroedinger equation are made.

  5. Automated Risk Identification of Myocardial Infarction Using Relative Frequency Band Coefficient (RFBC) Features from ECG

    OpenAIRE

    Bakul, Gohel; Tiwary, U.S

    2010-01-01

    Various structural and functional changes associated with ischemic (myocardial infarcted) heart cause amplitude and spectral changes in signals obtained at different leads of ECG. In order to capture these changes, Relative Frequency Band Coefficient (RFBC) features from 12-lead ECG have been proposed and used for automated identification of myocardial infarction risk. RFBC features reduces the effect of subject variabilty in body composition on the amplitude dependent features. The proposed ...

  6. Breath air measurement using wide-band frequency tuning IR laser photo-acoustic spectroscopy

    Science.gov (United States)

    Kistenev, Yury V.; Borisov, Alexey V.; Kuzmin, Dmitry A.; Bulanova, Anna A.; Boyko, Andrey A.; Kostyukova, Nadezhda Y.; Karapuzikov, Alexey A.

    2016-03-01

    The results of measuring of biomarkers in breath air of patients with broncho-pulmonary diseases using wide-band frequency tuning IR laser photo-acoustic spectroscopy and the methods of data mining are presented. We will discuss experimental equipment and various methods of intellectual analysis of the experimental spectra in context of above task. The work was carried out with partial financial support of the FCPIR contract No 14.578.21.0082 (ID RFMEFI57814X0082).

  7. Improving synthetic aperture focusing technique for thick concrete specimens via frequency banding

    Science.gov (United States)

    Clayton, Dwight A.

    2016-04-01

    A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. While standard Synthetic Aperture Focusing Technique (SAFT) is adequate for many defects with shallow concrete cover, some defects located under deep concrete cover are not easily identified using the standard SAFT. For many defects, particularly defects under deep cover, the use of frequency banded SAFT improves the detectability over standard SAFT. In addition to the improved detectability, the frequency banded SAFT also provides improved scan depth resolution that can be important in determining the suitability of a particular structure to perform its designed safety function. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To validate the advantages of frequency banded SAFT on thick concrete, a 2.134 m x 2.134 m x 1.016 m concrete test specimen with twenty deliberately embedded defects was fabricated.

  8. Effects of corrugation shape on frequency band-gaps for longitudinal wave motion in a periodic elastic layer.

    Science.gov (United States)

    Sorokin, Vladislav S

    2016-04-01

    The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band-gaps are determined by means of the method of varying amplitudes. For the general symmetric corrugation shape, the width of each odd band-gap is controlled only by one harmonic in the corrugation series with its number being equal to the number of the band-gap. Widths of even band-gaps, however, are influenced by all the harmonics involved in the corrugation series, so that the lower frequency band-gaps can emerge. These are band-gaps located below the frequency corresponding to the lowest harmonic in the corrugation series. For the general non-symmetric corrugation shape, the mth band-gap is controlled only by one, the mth, harmonic in the corrugation series. The revealed insights into the mechanism of band-gap formation can be used to predict locations and widths of all frequency band-gaps featured by any corrugation shape. These insights are general and can be valid also for other types of wave motion in periodic structures, e.g., transverse or torsional vibration. PMID:27106336

  9. Large Scale Assessment of Radio Frequency Interference Signatures in L-band SAR Data

    Science.gov (United States)

    Meyer, F. J.; Nicoll, J.

    2011-12-01

    Imagery of L-band Synthetic Aperture Radar (SAR) systems such as the PALSAR sensor on board the Advanced Land Observing Satellite (ALOS) has proven to be a valuable tool for observing environmental changes around the globe. Besides offering 24/7 operability, the L-band frequency provides improved interferometric coherence, and L-band polarimetric data has shown great potential for vegetation monitoring, sea ice classification, and the observation of glaciers and ice sheets. To maximize the benefit of missions such as ALOS PALSAR for environmental monitoring, data consistency and calibration are vital. Unfortunately, radio frequency interference (RFI) signatures from ground-based radar systems regularly impair L-band SAR data quality and consistency. With this study we present a large-scale analysis of typical RFI signatures that are regularly observed in L-band SAR data over the Americas. Through a study of the vast archive of L-band SAR data in the US Government Research Consortium (USGRC) data pool at the Alaska Satellite Facility (ASF) we were able to address the following research goals: 1. Assessment of RFI Signatures in L-band SAR data and their Effects on SAR Data Quality: An analysis of time-frequency properties of RFI signatures in L-band SAR data of the USGRC data pool is presented. It is shown that RFI-filtering algorithms implemented in the operational ALOS PALSAR processor are not sufficient to remove all RFI-related artifacts. In examples, the deleterious effects of RFI on SAR image quality, polarimetric signature, SAR phase, and interferometric coherence are presented. 2. Large-Scale Assessment of Severity, Spatial Distribution, and Temporal Variation of RFI Signatures in L-band SAR data: L-band SAR data in the USGRC data pool were screened for RFI using a custom algorithm. Per SAR frame, the algorithm creates geocoded frame bounding boxes that are color-coded according to RFI intensity and converted to KML files for analysis in Google Earth. From

  10. Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

    Science.gov (United States)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

  11. Radio frequency interference at Jodrell Bank Observatory within the protected 21 cm band

    Science.gov (United States)

    Tarter, J.

    1989-01-01

    Radio frequency interference (RFI) will provide one of the most difficult challenges to systematic Searches for Extraterrestrial Intelligence (SETI) at microwave frequencies. The SETI-specific equipment is being optimized for the detection of signals generated by a technology rather than those generated by natural processes in the universe. If this equipment performs as expected, then it will inevitably detect many signals originating from terrestrial technology. If these terrestrial signals are too numerous and/or strong, the equipment will effectively be blinded to the (presumably) weaker extraterrestrial signals being sought. It is very difficult to assess how much of a problem RFI will actually represent to future observations, without employing the equipment and beginning the search. In 1983 a very high resolution spectrometer was placed at the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England. This equipment permitted an investigation of the interference environment at Jodrell Bank, at that epoch, and at frequencies within the 21 cm band. This band was chosen because it has long been "protected" by international agreement; no transmitters should have been operating at those frequencies. The data collected at Jodrell Bank were expected to serve as a "best case" interference scenario and provide the minimum design requirements for SETI equipment that must function in the real and noisy environment. This paper describes the data collection and analysis along with some preliminary conclusions concerning the nature of the interference environment at Jodrell Bank.

  12. Metastability and inter-band frequency modulation in networks of oscillating spiking neuron populations.

    Directory of Open Access Journals (Sweden)

    David Bhowmik

    Full Text Available Groups of neurons firing synchronously are hypothesized to underlie many cognitive functions such as attention, associative learning, memory, and sensory selection. Recent theories suggest that transient periods of synchronization and desynchronization provide a mechanism for dynamically integrating and forming coalitions of functionally related neural areas, and that at these times conditions are optimal for information transfer. Oscillating neural populations display a great amount of spectral complexity, with several rhythms temporally coexisting in different structures and interacting with each other. This paper explores inter-band frequency modulation between neural oscillators using models of quadratic integrate-and-fire neurons and Hodgkin-Huxley neurons. We vary the structural connectivity in a network of neural oscillators, assess the spectral complexity, and correlate the inter-band frequency modulation. We contrast this correlation against measures of metastable coalition entropy and synchrony. Our results show that oscillations in different neural populations modulate each other so as to change frequency, and that the interaction of these fluctuating frequencies in the network as a whole is able to drive different neural populations towards episodes of synchrony. Further to this, we locate an area in the connectivity space in which the system directs itself in this way so as to explore a large repertoire of synchronous coalitions. We suggest that such dynamics facilitate versatile exploration, integration, and communication between functionally related neural areas, and thereby supports sophisticated cognitive processing in the brain.

  13. Ultra-slow frequency bands reflecting potential coherence between neocortical brain regions.

    Science.gov (United States)

    Zhang, X; Wang, Y-T; Wang, Y; Jung, T P; Huang, M; Cheng, C K; Mandell, A J

    2015-03-19

    Recent studies of electromagnetic ultra-slow waves (⩽0.1Hz) have suggested that they play a role in the integration of otherwise disassociated brain regions supporting vital functions (Ackermann and Borbely, 1997; Picchioni et al., 2010; Knyazev, 2012; Le Bon et al., 2012). We emphasize this spectral domain in probing sensor coherence issues raised by these studies using Hilbert phase coherences in the human MEG. In addition, we ask: will temporal-spatial phase coherence in regional brain oscillations obtained from the ultraslow spectral bands of multi-channel magnetoencephalograms (MEG) differentiate resting, "task-free" MEG records of normal control and schizophrenic subjects? The goal of the study is a comparison of the relative persistence of intra-regional phase locking values (PLVs), among 10, region-defined, sensors in examined in the resting multichannel, MEG records as a function of spectral frequency bands and diagnostic category. The following comparison of Hilbert-transform-engendered relative phases of each designated spectral band was made using their pair-wise PLVs. This indicated the proportion of shared cycle time in which the phase relations between the index location and reference leads were maintained. Leave one out, bootstrapping of the PLVs via a support vector machine (SVM), classified clinical status with 97.3% accuracy. It was generally the case that spectral bands ⩽1.0Hz generated the highest values of the PLVs and discriminated best between control and patient populations. We conclude that PLV analysis of the oscillatory patterns of MEG recordings in the ultraslow frequency bands suggest their functional significance in intra-regional signal coherence and provide a higher rate of classification of patients and normal subjects than the other spectral domains examined. PMID:25592429

  14. Audio-Band Frequency-Dependent Squeezing for Gravitational-Wave Detectors

    Science.gov (United States)

    Oelker, Eric; Isogai, Tomoki; Miller, John; Tse, Maggie; Barsotti, Lisa; Mavalvala, Nergis; Evans, Matthew

    2016-01-01

    Quantum vacuum fluctuations impose strict limits on precision displacement measurements, those of interferometric gravitational-wave detectors among them. Introducing squeezed states into an interferometer's readout port can improve the sensitivity of the instrument, leading to richer astrophysical observations. However, optomechanical interactions dictate that the vacuum's squeezed quadrature must rotate by 90° around 50 Hz. Here we use a 2-m-long, high-finesse optical resonator to produce frequency-dependent rotation around 1.2 kHz. This demonstration of audio-band frequency-dependent squeezing uses technology and methods that are scalable to the required rotation frequency and validates previously developed theoretical models, heralding application of the technique in future gravitational-wave detectors.

  15. Radio frequency electromagnetic field compliance assessment of multi-band and MIMO equipped radio base stations.

    Science.gov (United States)

    Thors, Björn; Thielens, Arno; Fridén, Jonas; Colombi, Davide; Törnevik, Christer; Vermeeren, Günter; Martens, Luc; Joseph, Wout

    2014-05-01

    In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances.

  16. Coherent Radiation from Extensive Air Showers in the Ultra-High Frequency Band

    CERN Document Server

    Alvarez-Muñiz, Jaime; Romero-Wolf, Andrés; Tueros, Matías; Zas, Enrique

    2012-01-01

    Using detailed Monte Carlo simulations we have characterized the features of the radio emission of inclined air showers in the Ultra-High Frequency band (300 MHz - 3 GHz). The Fourier-spectrum of the radiation is shown to have a sizable intensity well into the GHz frequency range. The emission is mainly due to transverse currents induced by the geomagnetic field and to the excess charge produced by the Askaryan effect. At these frequencies only a significantly reduced volume of the shower around the axis contributes coherently to the signal observed on the ground. The size of the coherently emitting volume depends on frequency, shower geometry and observer position, and is interpreted in terms of the relative time delays. At ground level, the maximum emission at high frequencies is concentrated in an elliptical ring-like region around the intersection of a Cherenkov cone with its vertex at shower maximum and the ground. The frequency spectrum of inclined showers when observed at positions that view shower max...

  17. Electromagnetic Compatibility Studies: LTE BS vs. Aeronautical Radionavigation Services in 694-790 MHz Frequency Band

    Directory of Open Access Journals (Sweden)

    Stankevičius Evaldas

    2014-10-01

    Full Text Available This paper presents the sharing analysis of the 694–790 MHz frequency band for Mobile services IMT and Aeronautical radio-navigation services (ARNS using SEAMCAT (established by CEPT software based on the statistical simulation (Monte-Carlo method. In 2012 the World Radiocommunication Conference (WRC-12 decided to allocate the 694–790 MHz frequency band (the so-called 700 MHz band to mobile services IMT (excluding aeronautical mobile after WRC-15 conference. But this agreement raises electromagnetic compatibility problems, which should be solved until WRC-15 [1]. This study was carried out in two phases: first applying theoretical analysis, then statistical Monte-Carlo simulations with SEAMCAT software tool in order to verify results obtained in theoretical approach. Analytical calculations shows that the required protection distances between ARNS stations and the MS base stations are 132 km. The obtained results from SEAMCAT simulations indicate that separation distance should be above 100 km. These results illustrate that the systems are not electromagnetically compatible. The possible mitigation technic could be antenna pattern correction.

  18. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions. 80.361 Section 80.361 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Radiotelegraphy § 80.361 Frequencies...

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

    NARCIS (Netherlands)

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

    2011-01-01

    An intermediate frequency (IF) band digitizing radiometer system in the 100–200 GHz frequency range has been developed for Tokamak diagnostics and control, and other fields of research which require a high flexibility in frequency resolution combined with a large bandwidth and the retrieval of the f

  20. Microwave frequency detector at X-band using GaAs MMIC technology

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun; Liao Xiaoping; Jiao Yongchang

    2009-01-01

    The design,fabrication,and experimental results of an MEMS microwave frequency detector are presented for the first time.The structure consists of a microwave power divider,two CPW transmission lines,a microwave power combiner,an MEMS capacitive power sensor and a thermopile.The detector has been designed and fabricated on GaAs substrate using the MMIC process at the X-band successfully.The MEMS capacitive power sensor is used for detecting the high power signal,while the thermopile is used for detecting the low power signal.Signals of 17 and 10 dBm are measured over the X-band.The sensitivity is 0.56 MHz/fF under 17 dBm by the capacitive power sensor,and 6.67 MHz//μV under 10 dBm by the thermopile.respectively.The validity of the presented design has been confirmed by the experiment.

  1. Dual-band frequency selective surface with quasi-elliptic bandpass response

    Institute of Scientific and Technical Information of China (English)

    Zhou Hang; Qu Shao-Bo; Peng Wei-Dong; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Bai Peng; Xu Zhuo

    2012-01-01

    Based on the substrate integrated waveguide technology,we present a dual-band frequency selective surface (FSS) with a quasi-elliptic bandpass response. The characteristics of the quasi-elliptic bandpass response are realized by shunting two substrate integrated waveguide cavities of different sizes,with the same slots on both sides of the metal surfaces.Four cavities of different sizes and two slots of different sizes are used to design the novel FSS.Every bandpass response with sharp sidebands is induced by two transmission nulls that are generated by the coupling between the slot aperture resonance and the cavity resonance.The simulation results show that such dual-band FSS has the advantages of high selectivity and stable performance at different oblique incident angles.Moreover,it is easy to fabricate.

  2. Dual band multi frequency rectangular patch microstrip antenna with flyswatter shaped slot for wireless systems

    Science.gov (United States)

    Bhardwaj, Dheeraj; Saraswat, Shriti; Gulati, Gitansh; Shekhar, Snehanshu; Joshi, Kanika; Sharma, Komal

    2016-03-01

    In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S11) have been investigated. The antenna design is primarily focused on achieving a dual band operation.

  3. Airborne Remote Observations of L-Band Radio Frequency Interference and Implications for Satellite Missions

    Science.gov (United States)

    Laymon, Charles; Srinivasan, Karthik; Limaye, Ashutosh

    2011-01-01

    Passive remote sensing of the Earth s surface and atmosphere from space has significant importance in operational and research environmental studies, in particular for the scientific understanding, monitoring and prediction of climate change and its impacts. Passive remote sensing requires the measurement of naturally occurring radiations, usually of very low power levels, which contain essential information on the physical process under investigation. As such, these sensed radio frequency bands are a unique natural resource enabling space borne passive sensing of the atmosphere and the Earth s surface that deserves adequate allocation to the Earth Exploration Satellite Service and absolute protection from interference. Unfortunately, radio frequency interference (RFI) is an increasing problem for Earth remote sensing, particularly for passive observations of natural emissions. Because these natural signals tend to be very weak, even low levels of interference received by a passive sensor may degrade the fidelity of scientific data. The characteristics of RFI (low-level interference and radar-pulse noise) are not well known because there has been no systematic surveillance, spectrum inventory or mapping of RFI. While conducting a flight experiment over central Tennessee in May 2010, RFI, a concern for any instrument operating in the passive L band frequency, was observed across 16 subbands between 1402-1427 MHz. Such a survey provides rare characterization data from which to further develop mitigation technologies as well as to identify bandwidths to avoid in future sensor formulation.

  4. Frequency band-importance functions for auditory and auditory-visual speech recognition

    Science.gov (United States)

    Grant, Ken W.

    2005-04-01

    In many everyday listening environments, speech communication involves the integration of both acoustic and visual speech cues. This is especially true in noisy and reverberant environments where the speech signal is highly degraded, or when the listener has a hearing impairment. Understanding the mechanisms involved in auditory-visual integration is a primary interest of this work. Of particular interest is whether listeners are able to allocate their attention to various frequency regions of the speech signal differently under auditory-visual conditions and auditory-alone conditions. For auditory speech recognition, the most important frequency regions tend to be around 1500-3000 Hz, corresponding roughly to important acoustic cues for place of articulation. The purpose of this study is to determine the most important frequency region under auditory-visual speech conditions. Frequency band-importance functions for auditory and auditory-visual conditions were obtained by having subjects identify speech tokens under conditions where the speech-to-noise ratio of different parts of the speech spectrum is independently and randomly varied on every trial. Point biserial correlations were computed for each separate spectral region and the normalized correlations are interpreted as weights indicating the importance of each region. Relations among frequency-importance functions for auditory and auditory-visual conditions will be discussed.

  5. Adaptive Threshold Clipper Combining Receiver for Fast Frequency Hopping Systems during Partial-Band Noise Jamming

    Institute of Scientific and Technical Information of China (English)

    肖立民; 许希斌; 姚彦

    2001-01-01

    Diversity combining technologies are analyzed for fastfrequency-hopping spread spectrum systems during partial-band noise jamming to develop a novel combining receiver called an Adaptive Threshold Clipper Combining Receiver (ATCCR). The optimal clipping level for an ATCCR is analyzed, computed, and compared with several other diversity combining technologies. Since the ATCCR can estimate the power of the jamming and the number of jammed frequency cells to adaptively adjust the clipper's threshold, the system performance using the adaptive threshold clipper combining technique can be greatly improved.

  6. Emotion Recognition with Eigen Features of Frequency Band Activities Embedded in Induced Brain Oscillations Mediated by Affective Pictures.

    Science.gov (United States)

    Aydin, Serap; Demirtaş, Serdar; Ateş, Kahraman; Tunga, M Alper

    2016-05-01

    In this study, singular spectrum analysis (SSA) has been used for the first time in order to extract emotional features from well-defined electroencephalography (EEG) frequency band activities (BAs) so-called delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-16 Hz), beta (16-32 Hz), gamma (32-64 Hz). These five BAs were estimated by applying sixth-level multi-resolution wavelet decomposition (MRWD) with Daubechies wavelets (db-8) to single channel nonaveraged emotional EEG oscillations of 6 s for each scalp location over 16 recording sites (Fp1, Fp2, F3, F4, F7, F8, C3, C4, P3, P4, T3, T4, T5, T6, O1, O2). Every trial was mediated by different emotional stimuli which were selected from international affective picture system (IAPS) to induce emotional states such as pleasant (P), neutral (N), and unpleasant (UP). Largest principal components (PCs) of BAs were considered as emotional features and data mining approaches were used for the first time in order to classify both three different (P, N, UP) and two contrasting (P and UP) emotional states for 30 healthy controls. Emotional features extracted from gamma BAs (GBAs) for 16 recording sites provided the high classification accuracies of 87.1% and 100% for classification of three emotional states and two contrasting emotional states, respectively. In conclusion, we found the followings: (1) Eigenspectra of high frequency BAs in EEG are highly sensitive to emotional hemispheric activations, (2) emotional states are mostly mediated by GBA, (3) pleasant pictures induce the higher cortical activation in contrast to unpleasant pictures, (4) contrasting emotions induce opposite cortical activations, (5) cognitive activities are necessary for an emotion to occur. PMID:26971786

  7. Optimization of amplitude-frequency characteristic three elements band-pass filter with dielectric resonator by genetic algorithm

    Directory of Open Access Journals (Sweden)

    A. A. Trubin

    2010-01-01

    Full Text Available It’s proposed the program that is searching the coupling coefficients of dielectric resonators answering to the necessary gain-frequency characteristic of band pass microwave filter. The program is based on a genetic algorithm.

  8. Low Power Phase Locked Loop Frequency Synthesizer for 2.4 GHz Band Zigbee

    Directory of Open Access Journals (Sweden)

    Nesreen M.H. Ismail

    2009-01-01

    Full Text Available Problem statement: Wireless communication systems are required for many applications. There are different standards for these systems. IEEE 802.15.4 defines the communication system standard for zigbee. This study discussed designing one of the blocks of zigbee transceiver which is the Phase Locked Loop (PLL. A major target for any communication systems is saving battery power, especially for zigbee as it is meant to be a low cost communication system. Phase Locked Loop is responsible on carrier frequency selection in a communication system. It is the most power consumer block in the transceiver as well. The objective of this study was designing a low power fully integrated integer-N PLL frequency synthesizer targeting the 2.4 GHz band IEEE 802.15.4 Std zigbee. Approach: Minimizing total power consumption of PLL was achieved by introducing a novel design of Phase Frequency Detector (PFD and modifying the rest of the PLL blocks. The proposed PFD uses only 12 transistors and it preserved the main characteristics of the conventional PFD with a simple architecture. The Charge Pump (CP was single-ended source switch to save power and minimize mismatches. The Voltage Controlled Oscillator (VCO spans from 4.737-4.977 GHz band using LC resonator. The VCO worked at double the frequency band to avoid local oscillator leakage and feed through. The integer N divider used a 15/16 dual modulus. Results: The proposed PLL was designed using Silterra 0.18 um CMOS process. It consumed 3.2 mW with 1.8 voltage supply. Phase noise is-113.4 dBc Hz-1 at 1 MHz. The proposed PFD works up to 2.5 GHz with free dead zone. The Charge Pump (CP works with 20 uA. lock-in time is 25 us and total die area is 1×2 mm. All results were taken from extracted layout simulations. Conclusion: The results of this study indicated that a PLL can work with less power consumption and save the transceiver battery. The proposed PFD was suitable for high speed applications.

  9. A Pure-Python Robust Frequency Band Automatic Phase Picker for Seismic Monitoring

    Science.gov (United States)

    Chen, C.; Holland, A. A.

    2013-12-01

    We modify the FPPICK algorithm of Lomax et al. (2012) and implement an automatic phase picking algorithm implemented in Python. The algorithm takes advantage of existing seismological Python libraries, Obspy. The algorithm is designed to work on a variety of instrumentation and automatically adapts to different sampling rates. The time series signals are band-pass filtered for each band, octave, considered within the picker algorithm. The energy of the signal is calculated over an averaging window and multiplied by the instantaneous energy of the signal. This energy time-series is the statistic we can then examine for each frequency band considered. The summary statistic, which allows the identification of a trigger, is simply the maximum value of any frequency bands energy statistic at each sample time. A trigger is identified by using a control chart type statistic to identify when our statistics summary is changing rapidly and exceeds a specified number of standard deviations from the mean of the summary energy statistic. This has the advantage that the picker parameters don't necessarily need to be modified when processing data from a wide variety of instrumentation with different response characteristics. The algorithm also contains a method to determine the first motion direction associated with a pick as well as an uncertainty for the pick. As with any automatic phase identification system false picks can and do occur. A few simple algorithms are implemented to avoid false-picks, the picker can be configured not to include these checks. These algorithms remove picks that occur very close in time, and picks for which a phase has a smaller RMS than the previous time interval. The algorithm uses many techniques within Numpy to improve computation times. The algorithm effectively picks both P- and S-phase from local and regional earthquakes with only small amounts of picker parameter modifications. The picker can pick both P and S phases on local and regional

  10. Extremely low-frequency Lamb wave band gaps in a sandwich phononic crystal thin plate

    Science.gov (United States)

    Shen, Li; Wu, Jiu Hui; Liu, Zhangyi; Fu, Gang

    2015-11-01

    In this paper, a kind of sandwich phononic crystal (PC) plate with silicon rubber scatterers embedded in polymethyl methacrylate (PMMA) matrix is proposed to demonstrate its low-frequency Lamb wave band gap (BG) characteristics. The dispersion relationship and the displacement vector fields of the basic slab modes and the locally resonant modes are investigated to show the BG formation mechanism. The anti-symmetric Lamb wave BG is further studied due to its important function in reducing vibration. The analysis on the BG characteristics of the PC through changing their geometrical parameters is performed. By optimizing the structure, a sandwich PC plate with a thickness of only 3 mm and a lower boundary (as low as 23.9 Hz) of the first anti-symmetric BG is designed. Finally, sound insulation experiment on a sandwich PC plate with the thickness of only 2.5 mm is conducted, showing satisfactory noise reduction effect in the frequency range of the anti-symmetric Lamb BG. Therefore, this kind of sandwich PC plate has potential applications in controlling vibration and noise in low-frequency ranges.

  11. Controlled excitation of electromagnetic band-gap line and point defect modes at microwave frequencies

    Science.gov (United States)

    Schuster, M.; Klein, N.

    2003-03-01

    We report on the controlled excitation of line and point defect modes in a two-dimensional hexagonal electromagnetic band-gap structure made of rods of dielectric material (aluminium oxide). We compared simulation performed with a numerical field simulation software and experimental measurements at microwave frequencies with regard to coupling from external waveguides to line defects and subsequent coupling to resonant modes. We observed that for a line defect in the photonic crystal the impedance matching to a waveguide is strongly dependent on the defect width. We furthermore demonstrated that the coupling to a localized defect resonance can be strongly influenced by the variation of certain single lattice elements, affecting transmission behavior and quality factor of the resonant modes.

  12. Ocean dynamic noise energy flux directivity in the 400 Hz to 700 Hz frequency band

    Institute of Scientific and Technical Information of China (English)

    Vladimir A. Shchurov; Galina F. Ivanova; Marianna V. Kuyanova; Helen S. Tkachenko

    2007-01-01

    Results of field studies of underwater dynamic noise energy flux directivity at two wind speeds, 6 m/s and 12 m/s, in the 400 Hz to 700 Hz frequency band in the deep open ocean are presented. The measurements were made by a freely drifting telemetric combined system at 500 m depth. Statistical characteristics of the horizontal and vertical dynamic noise energy flux directivity are considered as functions of wind speed and direction. Correlation between the horizontal dynamic noise energy flux direction and that of the wind was determined; a mechanism of the horizontal dynamic noise energy flux generation is related to the initial noise field scattering on ocean surface waves.

  13. Quanty for core level spectroscopy - excitons, resonances and band excitations in time and frequency domain

    Science.gov (United States)

    Haverkort, Maurits W.

    2016-05-01

    Depending on the material and edge under consideration, core level spectra manifest themselves as local excitons with multiplets, edge singularities, resonances, or the local projected density of states. Both extremes, i.e., local excitons and non-interacting delocalized excitations are theoretically well under control. Describing the intermediate regime, where local many body interactions and band-formation are equally important is a challenge. Here we discuss how Quanty, a versatile quantum many body script language, can be used to calculate a variety of different core level spectroscopy types on solids and molecules, both in the frequency as well as the time domain. The flexible nature of Quanty allows one to choose different approximations for different edges and materials. For example, using a newly developed method merging ideas from density renormalization group and quantum chemistry [1-3], Quanty can calculate excitons, resonances and band-excitations in x-ray absorption, photoemission, x-ray emission, fluorescence yield, non-resonant inelastic x-ray scattering, resonant inelastic x-ray scattering and many more spectroscopy types. Quanty can be obtained from: http://www.quanty.org.

  14. Frequency of Sensory Neural Hearing Loss in Major Beta-Thalassemias in Southern Iran

    Directory of Open Access Journals (Sweden)

    Seyed-Taghi Heydari

    2010-09-01

    Full Text Available Objective:The thalassemias are among the most common genetic disorders worldwide, occurring more frequently in the Mediterranean region. The aim of this study was to determined frequency of sensory-neural hearing loss in major ß- thalassemias transfusion dependent patients in south of Iran. Methods:A cross sectional study on 308 cases of major beta-thalassemia patients referring to Thalassemia Center of Shiraz University of Medical Sciences between 2006-2007 years. The diagnosis of ß- thalassemia major was based on clinical history, complete blood count and hemoglobine electrophoresis. Clinical data such as serum ferritin level, deferoxamine (DFO dose, mean daily doses of DFO (mg/kg and audiometric variables was recorded. Findings:Out of 308 cases, 283 (96.5% had normal hearing and 10 (3.5% sensorineural hearing loss. There was no statically significant difference between two groups regarding mean age, weight, age at the first blood transfusion, age at the first DFO infusion. Conclusion:We found the lowest incidence of sensorineural hearing loss in a large population of patients suffered from major thalassemia who received DFO. We show that DFO is not ototoxic at a low dose. When considering all related literature, as a whole there has been much critical misrepresentation about DFO ototoxicity.

  15. Frequency of Sensory Neural Hearing Loss in Major Beta-Thalassemias in Southern Iran

    Science.gov (United States)

    Faramarzi, Abolhassan; Karimi, Mehran; Heydari, Seyed-Taghi; Shishegar, Mahmoud; Kaviani, Masoud

    2010-01-01

    Objective The thalassemias are among the most common genetic disorders worldwide, occurring more frequently in the Mediterranean region. The aim of this study was to determined frequency of sensory-neural hearing loss in major ß- thalassemias transfusion dependent patients in south of Iran. Methods A cross sectional study on 308 cases of major beta-thalassemia patients referring to Thalassemia Center of Shiraz University of Medical Sciences between 2006–2007 years. The diagnosis of ß- thalassemia major was based on clinical history, complete blood count and hemoglobine electrophoresis. Clinical data such as serum ferritin level, deferoxamine (DFO) dose, mean daily doses of DFO (mg/kg) and audiometric variables was recorded. Findings Out of 308 cases, 283 (96.5%) had normal hearing and 10 (3.5%) sensorineural hearing loss. There was no statically significant difference between two groups regarding mean age, weight, age at the first blood transfusion, age at the first DFO infusion. Conclusion We found the lowest incidence of sensorineural hearing loss in a large population of patients suffered from major thalassemia who received DFO. We show that DFO is not ototoxic at a low dose. When considering all related literature, as a whole there has been much critical misrepresentation about DFO ototoxicity. PMID:23056722

  16. Frequency of the Group A Beta Hemolytic Streptococcus Infection in Children Presenting with Acute Tonsillopharyngitis

    Directory of Open Access Journals (Sweden)

    Özgül Yiğit

    2009-06-01

    Full Text Available Aim: The aim of this study was to evaluate the frequency of group A beta hemolytic streptococcus (GABHS in children with tonsillopharyngitis and to assess their complaints and clinical findings.Materials and Method: A total of 420 children who presented to our outpatient department with acute tonsillopharyngitis were enrolled to the study. The clinical features of patients with positive throat cultures for GABHS were compared to those with negative culture results. Presence of fever (≥37.50C, axilary, vomiting, coryza, sore throat, cough, abdominal pain, tenderness of cervical lymph nodes, and tonsillopharyngitis were recorded. Results: The mean age of the patients was 6.5±3.4 years (range, 1 to 14 years. The positive throat culture rate for GABHS was 22.62% (95 of 420 patients. It was found that fever, sore throat, cough, abdominal pain and tender cervical lymph nodes were significantly more frequent in patients with positive throat culture for GABHS than those with negative result for GABHS.Conclusion: GABHS should be firstly considered in patients presenting with symptoms of fever, sore throat, cough, abdominal pain and tenderness of cervical lymph nodes. (Journal of Current Pediatrics 2009; 7: 13-7

  17. Practically Efficient Blind Speech Separation Using Frequency Band Selection Based on Magnitude Squared Coherence and a Small Dodecahedral Microphone Array

    Directory of Open Access Journals (Sweden)

    Kazunobu Kondo

    2012-01-01

    Full Text Available Small agglomerative microphone array systems have been proposed for use with speech communication and recognition systems. Blind source separation methods based on frequency domain independent component analysis have shown significant separation performance, and the microphone arrays are small enough to make them portable. However, the level of computational complexity involved is very high because the conventional signal collection and processing method uses 60 microphones. In this paper, we propose a band selection method based on magnitude squared coherence. Frequency bands are selected based on the spatial and geometric characteristics of the microphone array device which is strongly related to the dodecahedral shape, and the selected bands are nonuniformly spaced. The estimated reduction in the computational complexity is 90% with a 68% reduction in the number of frequency bands. Separation performance achieved during our experimental evaluation was 7.45 (dB (signal-to-noise ratio and 2.30 (dB (cepstral distortion. These results show improvement in performance compared to the use of uniformly spaced frequency band.

  18. High frequency of beta thalassaemia in a small island population in Melanesia.

    OpenAIRE

    Bowden, D K; Hill, A V; Weatherall, D. J.; Clegg, J B

    1987-01-01

    A study of the causes of anaemia in the south west Pacific archipelago of Vanuatu has identified one island, Maewo, where the carrier rate for beta thalassaemia exceeds 20%, one of the highest recorded incidences in the world. Homozygous beta thalassaemia is a major cause of infant mortality and a serious drain on health resources on this island. Interactions of beta thalassaemia with various forms of alpha + thalassaemia were common in this population. Coexistent alpha + thalassaemia leads t...

  19. Multi-cavity coupling acoustic metamaterials with low-frequency broad band gaps based on negative mass density

    Science.gov (United States)

    Yang, Chuanhui; Wu, Jiu Hui; Cao, Songhua; Jing, Li

    2016-08-01

    This paper studies a novel kind of low-frequency broadband acoustic metamaterials with small size based on the mechanisms of negative mass density and multi-cavity coupling. The structure consists of a closed resonant cavity and an open resonant cavity, which can be equivalent to a homogeneous medium with effective negative mass density in a certain frequency range by using the parameter inversion method. The negative mass density makes the anti-resonance area increased, which results in broadened band gaps greatly. Owing to the multi-cavity coupling mechanism, the local resonances of the lower frequency mainly occur in the closed cavity, while the local resonances of the higher frequency mainly in the open cavity. Upon the interaction between the negative mass density and the multi-cavity coupling, there exists two broad band gaps in the range of 0-1800 Hz, i.e. the first-order band gap from 195 Hz to 660 Hz with the bandwidth of 465 Hz and the second-order band gap from 1157 Hz to 1663 Hz with the bandwidth of 506 Hz. The acoustic metamaterials with small size presented in this paper could provide a new approach to reduce the low-frequency broadband noises.

  20. Dielectric properties and emissivity of seawater at C-band microwave frequency.

    Science.gov (United States)

    Murugkar, A G; Joshi, A S; Kurtadikar, M L

    2012-10-01

    Microwave remote sensing applications over ocean using radar and radiometers, a precise knowledge of emissivity and reflectivity, are required. Emissivity of ocean surface is a function of the surface configuration, frequency of radiation, temperature and its dielectric properties. The emissivity of a smooth ocean surface at a particular wavelength is determined by its complex dielectric properties. In present study, laboratory measurements of complex dielectric properties, real part epsilon', and imaginary part epsilon", of surface seawater samples collected from Bay of Bengal and Arabian Sea are carried out. Measurements of these seawater samples are done at 5 GHz and 30 degrees C using an automated C-band microwave bench set up. The salinity of samples is also measured using autosalinometer. The salinity values are used to determine epsilon' and epsilon" using the Debye equations. The normal incidence emissivity and brightness temperature values for smooth sea surface are reported for surface samples. The dielectric constant epsilon' decreases and dielectric loss increases with increase in salinity at 5 GHz and 30 degrees C. At normal incidence, emissivity is almost constant for varying salinities.

  1. Low Noise Quantum Frequency Conversion from Rb Wavelengths to Telecom O-band

    Science.gov (United States)

    Li, Xiao; Solmeyer, Neal; Stack, Daniel; Quraishi, Qudsia

    2015-05-01

    Ideal quantum repeaters would be composed of long-lived quantum memories entangled with flying qubits. They are becoming essential elements to achieve quantum communication over long distances in a quantum network. However, quantum memories based on neutral atoms operate at wavelengths in the near infrared, unsuitable for long distance communication. The ability to coherently convert photons entangled with quantum memories into telecom wavelengths reduces the transmission loss in optical fibers and therefore dramatically improves the range of a quantum repeater. Furthermore, quantum frequency conversion (QFC) can enable entanglement and communication between different types of quantum memories, thus creating a versatile hybrid quantum network. A recent experiment has shown the conversion of heralded photons from Rb-based memories to the telecom C-band. We implement a setup using a nonlinear PPLN waveguide for the QFC into a wavelength region where the noise-floor would be limited by dark counts rather than pump photons. Our approach uses a pump laser at a much longer wavelength. It has the advantage that the strong pump itself and the broad background in the PPLN can be nearly completely filtered from the converted signal. Such low background level allows for the conversion to be done on the heralding photon, which enables the generated entanglement to be used in a scalable way to multiple nodes remotely situated and to subsequent protocols.

  2. Analysis and comparison model for measuring tropospheric scintillation intensity for Ku-band frequency in Malaysia

    Directory of Open Access Journals (Sweden)

    Mandeep JS

    2011-06-01

    Full Text Available This study has been based on understanding local propagation signal data distribution characteristics and identifying and predicting the overall impact of significant attenuating factors regarding the propagation path such as impaired propagation for a signal being transmitted. Predicting propagation impairment is important for accurate link budgeting, thereby leading to better communication network system designation. This study has thus used sample data for one year concerning beacon satellite operation in Malaysia from April 2008 to April 2009. Data concerning 12GHz frequency (Ku-band and 40° elevation angle was collected and analysed, obtaining average signal amplitude value, ÷ and also standard deviation ó which is normally measured in dB to obtain long-term scintillation intensity distribution. This analysis showed that scintillation intensity distribution followed Gaussian distribution for long-term data distribution. A prediction model was then selected based on the above; Karasawa,
    ITU-R, Van de Kamp and Otung models were compared to obtain the best prediction model performance for selected data regarding specific meteorological conditions. This study showed that the Karasawa model had the best performance for predicting scintillation intensity for the selected da ta.

  3. Dielectric properties and emissivity of seawater at C-band microwave frequency.

    Science.gov (United States)

    Murugkar, A G; Joshi, A S; Kurtadikar, M L

    2012-10-01

    Microwave remote sensing applications over ocean using radar and radiometers, a precise knowledge of emissivity and reflectivity, are required. Emissivity of ocean surface is a function of the surface configuration, frequency of radiation, temperature and its dielectric properties. The emissivity of a smooth ocean surface at a particular wavelength is determined by its complex dielectric properties. In present study, laboratory measurements of complex dielectric properties, real part epsilon', and imaginary part epsilon", of surface seawater samples collected from Bay of Bengal and Arabian Sea are carried out. Measurements of these seawater samples are done at 5 GHz and 30 degrees C using an automated C-band microwave bench set up. The salinity of samples is also measured using autosalinometer. The salinity values are used to determine epsilon' and epsilon" using the Debye equations. The normal incidence emissivity and brightness temperature values for smooth sea surface are reported for surface samples. The dielectric constant epsilon' decreases and dielectric loss increases with increase in salinity at 5 GHz and 30 degrees C. At normal incidence, emissivity is almost constant for varying salinities. PMID:25151713

  4. Potential radio frequency interference with the GPS L5 band for radio occultation measurements

    Directory of Open Access Journals (Sweden)

    A. M. Wolff

    2014-05-01

    Full Text Available New Radio Occultation (RO receivers are planned to utilize the newly implemented Global Positioning System (GPS L5 signal centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance Measuring Equipment (DME and Tactical Air Navigation (TACAN stations share the same frequency band as the GPS L5 signal. DME/TACAN signals have been identified to be a means of interference for any GPS L5 receiver. This study focuses on implementing a Systems Tools Kit (STK simulation to gain insight into the power received by a RO satellite in Low Earth Orbit (LEO from a DME/TACAN transmission. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME/TACAN station as well as a tool to predict the number of interfering DME/TACAN stations at any point in time. Taking a conservative approach, the signal power received was much greater than the typical power level received by a RO satellite from a GPS satellite transmission. This relatively high received power along with a high number of interfering DME/TACAN stations as an RO satellite passes over North America or Western Europe indicate that DME/TACAN interference may conflict with RO receivers.

  5. Quantum Transduction of Telecommunications-band Single Photons from a Quantum Dot by Frequency Upconversion

    CERN Document Server

    Rakher, Matthew T; Slattery, Oliver; Tang, Xiao; Srinivasan, Kartik

    2010-01-01

    The ability to transduce non-classical states of light from one wavelength to another is a requirement for integrating disparate quantum systems that take advantage of telecommunications-band photons for optical fiber transmission of quantum information and near-visible, stationary systems for manipulation and storage. In addition, transducing a single-photon source at 1.3 {\\mu}m to visible wavelengths for detection would be integral to linear optical quantum computation due to the challenges of detection in the nearinfrared. Recently, transduction at single-photon power levels has been accomplished through frequency upconversion, but it has yet to be demonstrated for a true single-photon source. Here, we transduce the triggered single-photon emission of a semiconductor quantum dot at 1.3 {\\mu}m to 710 nm with a total detection (internal conversion) efficiency of 21% (75%). We demonstrate that the 710 nm signal maintains the quantum character of the 1.3 {\\mu}m signal, yielding a photon anti-bunched second-ord...

  6. Frequency Shift and Sub-band Effect in Pair-Production Process Under Adiabatic Closing the External Field

    Science.gov (United States)

    Song, Xinfang; Wang, Wenyuan; Fu, Libin

    2016-09-01

    Oscillating electric field is chosen to investigate the electron-positron pair production process by using a quantum kinetic theory and the effective mass model [Phys. Rev. Lett. 112, 050402 (2014)]. The particle yield exhibits a characteristic oscillatory structure which is related to the multi-photon thresholds. The true peak positions are typically slightly above the naive threshold estimate, which is defined as frequency shift. During the numerical calculations, we find the frequency shift can be affected by the system parameters under adiabatic closing the external field, it is worthwhile to study in detail. In this paper, we investigate the frequency shift and the sub-band effect in electron-positron pair production with oscillating electric field. First, a quantum kinetic theory and the effective mass are presented to obtain the frequency shift, the results are fitted very well. And we find the frequency shift and the sub-band effect can be influenced by pulse duration, photon number, and strength of the external field. The frequency shift becomes evident as increases of photon number and the external field strength. The sub-band width is relatively lower at longer pulse duration, higher photon number region, and weaker external field. The results shown in the paper are helpful for understanding multi-photon pair production process in the strong field.

  7. Frequency Shift and Sub-band Effect in Pair-Production Process Under Adiabatic Closing the External Field

    Science.gov (United States)

    Song, Xinfang; Wang, Wenyuan; Fu, Libin

    2016-04-01

    Oscillating electric field is chosen to investigate the electron-positron pair production process by using a quantum kinetic theory and the effective mass model [Phys. Rev. Lett. 112, 050402 (2014)]. The particle yield exhibits a characteristic oscillatory structure which is related to the multi-photon thresholds. The true peak positions are typically slightly above the naive threshold estimate, which is defined as frequency shift. During the numerical calculations, we find the frequency shift can be affected by the system parameters under adiabatic closing the external field, it is worthwhile to study in detail. In this paper, we investigate the frequency shift and the sub-band effect in electron-positron pair production with oscillating electric field. First, a quantum kinetic theory and the effective mass are presented to obtain the frequency shift, the results are fitted very well. And we find the frequency shift and the sub-band effect can be influenced by pulse duration, photon number, and strength of the external field. The frequency shift becomes evident as increases of photon number and the external field strength. The sub-band width is relatively lower at longer pulse duration, higher photon number region, and weaker external field. The results shown in the paper are helpful for understanding multi-photon pair production process in the strong field.

  8. Effects of weak nonlinearity on the dispersion relation and frequency band-gaps of a periodic Bernoulli–Euler beam

    DEFF Research Database (Denmark)

    Sorokin, Vladislav S.; Thomsen, Jon Juel

    2016-01-01

    The paper deals with analytically predicting the effects of weak nonlinearity on the dispersion relation and frequency band-gaps of a periodic Bernoulli– Euler beam performing bending oscillations. Two cases are considered: (i) large transverse deflections, where nonlinear (true) curvature...

  9. A high conversion-gain Q-band InP DHBT subharmonic mixer using LO frequency doubler

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor;

    2008-01-01

    The paper presents analysis and design of a Q-band subharmonic mixer (SHM) with high conversion gain. The SHM consists of a local oscillator (LO) frequency doubler, RF pre-amplifier, and single-ended mixer. The SHM has been fabricated in a high-speed InP double heterojunction bipolar transistor...

  10. Digital predistortion of 75–110 GHz W-band frequency multiplier for fiber wireless short range access systems

    DEFF Research Database (Denmark)

    Zhao, Ying; Deng, Lei; Pang, Xiaodan;

    2011-01-01

    We present a W-band fiber-wireless transmission system based on a nonlinear frequency multiplier for high-speed wireless short range access applications. By implementing a baseband digital signal predistortion scheme, intensive nonlinear distortions induced in a sextuple frequency multiplier can...... be effectively pre-compensated. Without using costly W-band components, a transmission system with 26km fiber and 4m wireless transmission operating at 99.6GHz is experimentally validated. Adjacent-channel power ratio (ACPR) improvements for IQ-modulated vector signals are guaranteed and transmission...... performances for fiber and wireless channels are studied. This W-band predistortion technique is a promising candidate for applications in high capacity wireless-fiber access systems....

  11. Formation mechanism of the low-frequency locally resonant band gap in the two-dimensional ternary phononic crystals

    Institute of Scientific and Technical Information of China (English)

    Wang Gang; Liu Yao-Zong; Wen Ji-Hong; Yu Dian-Long

    2006-01-01

    The low-frequency band gap and the corresponding vibration modes in two-dimensional ternary locally resonant phononic crystals are restudied successfully with the lumped-mass method. Compared with the work of C. Goffaux and J. Sanchez-Dehesa (Phys. Rev. B 67 14 4301(2003)), it is shown that there exists an error of about 50% in their calculated results of the band structure, and one band is missing in their results. Moreover, the in-plane modes shown in their paper are improper, which results in the wrong conclusion on the mechanism of the ternary locally resonant phononic crystals. Based on the lumped-mass method and better description of the vibration modes according to the band gaps, the locally resonant mechanism in forming the subfrequency gaps is thoroughly analysed. The rule used to judge whether a resonant mode in the phononic crystals can result in a corresponding subfrequency gap is also verified in this ternary case.

  12. Frequency distribution of sickle cell anemia, sickle cell trait and sickle/beta-thalassemia among anemic patients in Saudi Arabia

    OpenAIRE

    Elsayid, Mohieldin; Al-Shehri, Mohammed Jahman; Alkulaibi, Yasser Abdullah; Alanazi, Abdullah; Qureshi, Shoeb

    2015-01-01

    Background: Notwithstanding, the growing incidence of sickle cell hemoglobinopathies (SCH) such as sickle cell anemia (SCA) or sickle cell disease, sickle/beta-thalassemia; the exact prevalence remains obscure in Saudi Arabia. Hence, this study is an attempt to determine the frequency of SCA and sickle cell trait (SCT) among all anemic patients with SCH treated at the King Abdul-Aziz Medical City (KAMC), Riyadh, Saudi Arabia. Furthermore, the hemoglobin (Hb) S and other Hb patterns (Hb AS and...

  13. Triaxial tunable mechanical monolithic sensors for large band low frequency monitoring and characterization of sites and structures

    Science.gov (United States)

    Barone, F.; Giordano, G.; Acernese, F.; Romano, R.

    2016-04-01

    This paper describes the application of the monolithic UNISA Folded Pendulum, optimized as inertial sensor (seismometer) for low frequency applications for characterization of sites (including underground sites) and structures (e.g. buildings, bridges, historical monuments), but, in general, for applications requiring large band low-frequency performances coupled with high sensitivities. The main characteristics of this class of sensors are high sensitivity, large measurement band, compactness, lightness, scalability, tunability of the resonance frequency, low thermal noise and very good immunity to environmental noises. The horizontal and vertical versions of folded pendulum allow an effective state-of-the-art mechanical implementation of triaxial sensors, configurable both as seismometer and/or as accelerometer.

  14. Design of Frequency Selective Surface with Double Bands%双带频率选择表面设计

    Institute of Scientific and Technical Information of China (English)

    曲宝龙; 李旭东; 朱鹏刚

    2012-01-01

    In order to realize double-band properties of frequency selective surface (FSS), the composite element FSS, composed of rectangle grid and three-ring loop element, is presented. The spectral domain solution method is described in detail for FSS. The frequency response properties of FSS are analyzed for electromagnetic waves with different incident angles and polarizations based on the spectral domain method. The result shows that the designed FSS can maintain stable double-band, flat top transmission and sharp skirt properties for electromagnetic waves with different incidence angles and polarizations. The double-band properties show stop-band from 1. 8 GHz to 5.4 GHz and pass-band from 5.4 GHz to 20.0 GHz. The resonant frequency of stop-band is situated at about 3. 1 GHz, and the bandwidth of flat top transmission is over 14.3 GHz at —4 dB. The sharp skirt properties show that the S-band signal is reflected intensively and other band signals are transmitted, and multi-band communication is achieved. The composite FSS can be used in satellite communications, radomes and other fields.%为了实现频率选择表面(FSS)的双带特性,设计了由矩形栅格和三圆环组合单元FSS.对FSS的谱域求解方法进行了详细的描述.采用谱域法分析了不同角度和极化入射波下FSS的频率响应性能.结果表明,所设计的FSS对于不同入射角度和极化电磁波具有稳定的双带、平顶传输及陡峭下降边缘特性.双带特性大致表现为1.8~5.4 GHz的阻带和5.4~20.0 GHz的通带.阻带谐振频率稳定在3.1 GHz左右,而通带在-4 dB的平顶传输带宽达14.3 GHz以上.其陡峭下降边缘特性表现为S波段信号强烈反射,而其他波段信号通过,从而实现多波段通讯.该结构FSS可应用于卫星通信、雷达罩及其他相关领域.

  15. Dual-Frequency L-Band Antenna Array with Integrated Transmit/Receive Modules Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase I SBIR proposal we describe our plan to develop two key technologies for future combined radar/radiometer systems operating at L-band. The first, a...

  16. An Overview on Development of Passive Radar Based on the Low Frequency Band Digital Broadcasting and TV Signals

    Directory of Open Access Journals (Sweden)

    Wan Xian-rong

    2012-06-01

    Full Text Available Starting from the detection principle and characteristics of passive radar, this paper describes the development of passive radar based on the low frequency band (HF/VHF/UHF digital broadcasting and TV signal. Based on the radio coverage ratio and technical features of digital broadcasting and TV signals, the research status in abroad, especially in Europe, is introduced at first, on experimental systems, technical parameters, and comparative experiments. Then the latest development of passive radars, in different frequency bands in China, both theory and experimental study are presented. Followed is the commentary on the key techniques and problems of Digital Broadcasting-based Passive Radar (DBPR, including the waveform’s properties and its modification, reference signal extraction, multipath clutter rejection, target detection, tracking, and fusion as well as real-time signal processing. Finally, the prospects of development and application of this kind of passive radar are discussed.

  17. Investigate the Performance of Various Shapes of Planar Monopole Antenna on Modified Ground Plane Structures for L frequency Band Applications

    Directory of Open Access Journals (Sweden)

    Anshul Agarwal

    2013-11-01

    Full Text Available In this paper, various shapes of planar monopole antenna on different ground plane structures are presented. It is designed for the 1-2 GHz frequency band for L-band application. A monopole of square, circular, triangular and hexagon shape is mounted vertically on the dielectric of glass epoxy (FR4 lossy substrate with relative permittivity of 4.3, thickness of 1.6 mm above the ground plane through a single feeding strip. Simulation results such as impedance bandwidth, directivity, gain and radiation pattern are also analyzed and compared. The effect of feeding strip is a critical parameter for the performance of antenna, is studied for various shapes of monopole antenna are investigated. The radiation performance is also shown to be acceptable over a wide range of frequency.

  18. Design and characteristics of L-C thin films filter at microwave frequency band

    Science.gov (United States)

    Kim, In-Sung; Min, Bok-Ki; Song, Jae-Sung

    2005-12-01

    Multifunction corresponding to multimedia age has furthermore required high integration to the devices at microwave band, so more evolution for multi-layer integration like system on chip(SoC) becomes to be necessary. In wireless mobile communication, portable mobile phones grew up to a huge market. Microwave devices have played an important role in the wireless communication systems. One challenge in the implementation of circuit integration is in the design of micro wave band pass filter with thin film MOM capacitor and spiral inductor. In this paper, Cu and TaO thin film with RF sputtering was deposited for inductor and capacitor on the SiO II/Si(100) substrate. MIM capacitor and spiral inductor was fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, an important devices for mobile communication. Based on the high-Q values of passive components, MIM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and was 5 dB for a 900 MHz filter. This paper also discusses a theoretical analysis and practical design to L-C band pass filter.

  19. Mobile Communication Networks and Digital Television Broadcasting Systems in the Same Frequency Bands – Advanced Co-Existence Scenarios

    OpenAIRE

    L. Polak; Kaller, O.; L. Klozar; J. Sebesta; T. Kratochvil

    2014-01-01

    The increasing demand for wireless multimedia services provided by modern communication systems with stable services is a key feature of advanced markets. On the other hand, these systems can many times operate in a neighboring or in the same frequency bands. Therefore, numerous unwanted co-existence scenarios can occur. The aim of this paper is to summarize our results which were achieved during exploration and measurement of the co-existences between still used and upcoming mobile networks ...

  20. Path loss variation of on-body UWB channel in the frequency bands of IEEE 802.15.6 standard.

    Science.gov (United States)

    Goswami, Dayananda; Sarma, Kanak C; Mahanta, Anil

    2016-06-01

    The wireless body area network (WBAN) has gaining tremendous attention among researchers and academicians for its envisioned applications in healthcare service. Ultra wideband (UWB) radio technology is considered as excellent air interface for communication among body area network devices. Characterisation and modelling of channel parameters are utmost prerequisite for the development of reliable communication system. The path loss of on-body UWB channel for each frequency band defined in IEEE 802.15.6 standard is experimentally determined. The parameters of path loss model are statistically determined by analysing measurement data. Both the line-of-sight and non-line-of-sight channel conditions are considered in the measurement. Variations of parameter values with the size of human body are analysed along with the variation of parameter values with the surrounding environments. It is observed that the parameters of the path loss model vary with the frequency band as well as with the body size and surrounding environment. The derived parameter values are specific to the particular frequency bands of IEEE 802.15.6 standard, which will be useful for the development of efficient UWB WBAN system.

  1. Effect of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency

    Energy Technology Data Exchange (ETDEWEB)

    Ding Xueyong; Li Hongfan; Lv Zhensu [Polytechnic Institute of San Ya University, Sanya, Hainan 572022 (China)

    2012-09-15

    Based on the mode-coupling method, numerical analysis is presented to demonstrate the influence of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency. Results show that the interval between the band-gaps of the competing mode and the desired working mode is narrowed by use of positive-taper ripples, but is expanded if negative-taper ripples are employed, and the influence of the negative-taper ripples is obviously more advantageous than the positive-taper ripples; the band-gap overlap of modes can be efficiently separated by use of negative-taper ripples. The residual side-lobes of the frequency response in a coaxial Bragg structure with ripple taper also can be effectively suppressed by employing the windowing-function technique. These peculiarities provide potential advantage in constructing a coaxial Bragg cavity with high quality factor for single higher-order-mode operation of a high-power free-electron maser in the terahertz frequency range.

  2. Role of frequency band integration in sharpening frequency tunings of the inferior colliculus neurons in the big brown bat, Eptesicus fuscus

    Institute of Scientific and Technical Information of China (English)

    WU Feijian; CHEN Qicai; JEN Philip H.S.; SHEN Junxian

    2004-01-01

    By means of a particular two-tone stimulation paradigm in combination of using a pair of electrodes for simultaneously recording from two inferior colliculus (IC) neurons, the current in vivo study is undertaken to explore the role of frequency band integration (FBI) in sharpening of frequency tuning in the big brown bat, Eptesicus fuscus. Three major results are found: (1) The paired neurons correlated to FBI are located not only within the same frequency filter bandwidth (FFB), but also across different FFBs. The relations of their frequency tuning curves (FTCs) are mainly of two types: the flank-overlapped and overlaid patterns. (2) Although the sharpness of FTCs between paired neurons is mutual, the sharpening efficiency of neurons located within the same FFB is higher than that of neurons across FFBs, and the FTCs of neurons with the best frequencies (BF) of 20-30 kHz are most strongly sharpened. (3) The strength of FBI is weak near the BF but gradually increased with frequencies away from the BF of sound stimuli. This suggests that the dynamical FBI of the IC neurons located within and across the FFBs might be involved in the formation of functional FFB structures.

  3. Frequency-band signatures of visual responses to naturalistic input in ferret primary visual cortex during free viewing.

    Science.gov (United States)

    Sellers, Kristin K; Bennett, Davis V; Fröhlich, Flavio

    2015-02-19

    Neuronal firing responses in visual cortex reflect the statistics of visual input and emerge from the interaction with endogenous network dynamics. Artificial visual stimuli presented to animals in which the network dynamics were constrained by anesthetic agents or trained behavioral tasks have provided fundamental understanding of how individual neurons in primary visual cortex respond to input. In contrast, very little is known about the mesoscale network dynamics and their relationship to microscopic spiking activity in the awake animal during free viewing of naturalistic visual input. To address this gap in knowledge, we recorded local field potential (LFP) and multiunit activity (MUA) simultaneously in all layers of primary visual cortex (V1) of awake, freely viewing ferrets presented with naturalistic visual input (nature movie clips). We found that naturalistic visual stimuli modulated the entire oscillation spectrum; low frequency oscillations were mostly suppressed whereas higher frequency oscillations were enhanced. In average across all cortical layers, stimulus-induced change in delta and alpha power negatively correlated with the MUA responses, whereas sensory-evoked increases in gamma power positively correlated with MUA responses. The time-course of the band-limited power in these frequency bands provided evidence for a model in which naturalistic visual input switched V1 between two distinct, endogenously present activity states defined by the power of low (delta, alpha) and high (gamma) frequency oscillatory activity. Therefore, the two mesoscale activity states delineated in this study may define the degree of engagement of the circuit with the processing of sensory input.

  4. Lewis Investigates Frequency Sharing Between Future NASA Space Systems and Local Multipoint Distribution Systems in the 27-GHz Band

    Science.gov (United States)

    1997-01-01

    At the request of the Federal Communications Commission (FCC), the NASA Lewis Research Center undertook an intensive study to examine the feasibility of frequency sharing between future NASA space services and proposed Local Multipoint Distribution Systems (LMDS) in the 25.25- to 27.5-GHz band. This follows NASA's earlier involvement in the FCC's 1994 Negotiated Rule Making Committee which studied frequency sharing between Ka-band Fixed Satellite Services and LMDS in the 27.5- to 29.5-GHz band. LMDS is a terrestrial, cellular, wireless communication service primarily intended to provide television distribution from hub stations located within relatively small cells to fixed subscriber receivers. Some proposed systems, however, also plan to offer interactive services via subscriber-to-hub transmissions. LMDS providers anticipate that their systems will be a cost-effective alternative to cable television systems, especially in urban areas. LMDS proponents have expressed an interest in using frequencies below 27.5 GHz. NASA, however, plans to operate three types of space systems below 27.5 GHz. The H, I, and J follow-on satellites for the Tracking and Data Relay Satellite System (TDRSS), which are planned for launch beginning in 1999, are designed to receive high-data-rate transmissions (up to 800 Mbps) from low-Earth orbiting "user" spacecraft in the 25.25- to 27.5-GHz band. In this case, the potential interference is the aggregate interference from LMDS transmitters (both hubs and subscribers) into the TDRSS tracking receive beams as they sweep over the Earth's surface while tracking lower altitude user spacecraft.

  5. Bio-Soliton Model that predicts Non-Thermal Electromagnetic Radiation Frequency Bands, that either Stabilize or Destabilize Life Conditions

    CERN Document Server

    Geesink, J H

    2016-01-01

    Solitons, as self-reinforcing solitary waves, interact with complex biological phenomena such as cellular self-organisation. Soliton models are able to describe a spectrum of electromagnetism modalities that can be applied to understand the physical principles of biological effects in living cells, as caused by electromagnetic radiation. A bio-soliton model is proposed, that enables to predict which eigen-frequencies of non-thermal electromagnetic waves are life-sustaining and which are, in contrast, detrimental for living cells. The particular effects are exerted by a range of electromagnetic wave frequencies of one-tenth of a Hertz till Peta Hertz, that show a pattern of twelve bands, if positioned on an acoustic frequency scale. The model was substantiated by a meta-analysis of 240 published papers of biological radiation experiments, in which a spectrum of non-thermal electromagnetic waves were exposed to living cells and intact organisms. These data support the concept of coherent quantized electromagnet...

  6. Wide frequency independently controlled dual-band inkjet-printed antenna

    KAUST Repository

    AbuTarboush, Hattan F.

    2014-01-08

    A low-cost inkjet-printed multiband monopole antenna is presented. The unique advantage of the proposed antenna is the freedom to adjust and set the dual-band of the antenna independently over a wide range (148.83%). To demonstrate the independent control feature, the 2.4 and 3.4 GHz bands for the wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications are selected as an example. The measured impedance bandwidths for the 2.4 and 3.4 GHz are 15.2 and 23.7%, respectively. These dual-bands have the ability to be controlled independently between 1.1 and 7.5 GHz without affecting the other band. In addition, the proposed antenna can be assigned for different mobile and wireless applications such as GPS, PCS, GSM 1800, 1900, UMTS, and up to 5-GHz WLAN and WiMAX applications. The mechanism of independent control of each radiator through dimensional variation is discussed in detail. The antenna has a compact size of 10 × 37.3 × 0.44 mm3, leaving enough space for the driving electronics on the paper substrate. The measured results from the prototype are in good agreement with the simulated results. Owing to inkjet printing on an ordinary paper, the design is extremely light weight and highly suitable for low cost and large volume manufacturing. © The Institution of Engineering and Technology 2013.

  7. Estimating peak response frequencies in a tidal band in the seas adjacent to China with a numerical model

    Institute of Scientific and Technical Information of China (English)

    CUI Xinmei; FANG Guohong; TENG Fei; WU Di

    2015-01-01

    A numerical method is designed to examine the response properties of real sea areas to open ocean forcing. The application of this method to modeling the China's adjacent seas shows that the Bohai Sea has a highest peak response frequency (PRF) of 1.52 d−1; the northern Yellow Sea has a PRF of 1.69 d−1; the Gyeonggi Bay has a high amplitude gain plateau in the frequency band roughly from 1.7 to 2.7 d−1; the Yellow Sea (includ-ing the Gyeonggi Bay), the East China Sea shelf and the Taiwan Strait have a common high amplitude gain band with frequencies around 1.76 to 1.78 d−1 and are shown to be a system that responds to the open ocean forcing in favor of amplifying the waves with frequencies in this band; the Beibu Gulf, the Gulf of Thailand and the South China Sea deep basin have PRFs of 0.91, 1.01 and 0.98 d−1 respectively. In addition, the East China Sea has a Poincare mode PRF of 3.91 d−1. The PRFs of the Bohai Sea, the northern Yellow Sea, the Bei-bu Gulf and the South China Sea can be explained by a classical quarter (half for the Bohai Sea) wavelength resonance theory. The results show that further investigations are needed for the response dynamics of the Yellow Sea-East China Sea-Taiwan Strait system, the East China Sea Poincare mode, the Taiwan Strait, and the Gulf of Thailand.

  8. Flexible metamaterial narrow-band-pass filter based on magnetic resonance coupling between ultra-thin bilayer frequency selective surfaces

    International Nuclear Information System (INIS)

    A novel flexible metamaterial narrow-band-pass filter is designed and proved to be reliable by both numerical simulations and experimental measurements. The unit cell of the designed structure consists of circle ring resonators on top of a thin dielectric layer backed by a metallic mesh. The investigations on the distribution of the surface current and magnetic field as well as the analysis of the equivalent circuit model reveal that the magnetic resonance response between layers induced by the reverse surface current contributes to the high quality factor band-pass property. Importantly, it is a flexible design with a tunable resonance frequency by just changing the radius of the circle rings and can also be easily extended to have the multi-band-pass property. Moreover, this simplified structure with low duty cycle and ultra-thin thickness is also a symmetric design which is insensitive to the polarization and incident angles. Therefore, such a metamaterial narrow-band-pass filter is of great importance in the practical applications such as filtering and radar stealth, and especially for the conformal structure applications in the infrared and optical window area. (paper)

  9. High frequency wide-band transformer uses coax to achieve high turn ratio and flat response

    Science.gov (United States)

    De Parry, T.

    1966-01-01

    Center-tap push-pull transformer with toroidal core helically wound with a single coaxial cable creates a high frequency wideband transformer. This transformer has a high-turn ratio, a high coupling coefficient, and a flat broadband response.

  10. An L-Band Radio Frequency Interference (RFI) Detection and Mitigation Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radio Frequency Interference (RFI) can render microwave radiometer measurements useless. We have proposed a method and an architecture that can be used to identify...

  11. A C-Band Radio Frequency Interference (RFI) Detection and Mitigation Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radio Frequency Interference (RFI) can render microwave radiometer measurements useless. We propose a method and an architecture that can be used to identify...

  12. Circularly Polarized S Band Dual Frequency Square Patch Antenna Using Glass Microfiber Reinforced PTFE Composite

    OpenAIRE

    Samsuzzaman, M.; M. T. Islam; Haslina Arshad; J. S. Mandeep; Misran, N

    2014-01-01

    Circularly polarized (CP) dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE) composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the ...

  13. Correction and Characterization of Radio Frequency Interference Signatures in L-band Synthetic Aperture Radar Data

    OpenAIRE

    Meyer, Franz; Nicoll, Jeremy; Doulgeris, Anthony Paul

    2013-01-01

    Radio frequency interference (RFI) is a known issue in low-frequency radar remote sensing. In synthetic aperture radar (SAR) image processing, RFI can cause severe degradation of image quality, distortion of polarimetric signatures, and an increase of the SAR phase noise level. To address this issue, a processing system was developed that is capable of reliably detecting, characterizing, and mitigating RFI signatures in SAR observations. In addition to being the basis for image correction, th...

  14. Watts linkage based large band low frequency sensors for scientific applications

    Science.gov (United States)

    Barone, F.; Giordano, G.; Acernese, F.; Romano, R.

    2016-07-01

    The UNISA Folded Pendulum class of horizontal and vertical sensors, based on an innovative configuration of the classical Watt's linkage mechanical architecture, allows the design and implementation of very large band monolithic sensors (10-7 Hz to102 Hz), whose sensitivities for the most common applications are defined by the noise introduced by their readouts (e.g. space and underwater applications, including UHV and cryogenics ones.

  15. Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data

    Science.gov (United States)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Kleynhans, Waldo; Wessels, Konrad; Asner, Gregory; Leblon, Brigitte

    2015-07-01

    Structural parameters of the woody component in African savannahs provide estimates of carbon stocks that are vital to the understanding of fuelwood reserves, which is the primary source of energy for 90% of households in South Africa (80% in Sub-Saharan Africa) and are at risk of over utilisation. The woody component can be characterised by various quantifiable woody structural parameters, such as tree cover, tree height, above ground biomass (AGB) or canopy volume, each been useful for different purposes. In contrast to the limited spatial coverage of ground-based approaches, remote sensing has the ability to sense the high spatio-temporal variability of e.g. woody canopy height, cover and biomass, as well as species diversity and phenological status - a defining but challenging set of characteristics typical of African savannahs. Active remote sensing systems (e.g. Light Detection and Ranging - LiDAR; Synthetic Aperture Radar - SAR), on the other hand, may be more effective in quantifying the savannah woody component because of their ability to sense within-canopy properties of the vegetation and its insensitivity to atmosphere and clouds and shadows. Additionally, the various components of a particular target's structure can be sensed differently with SAR depending on the frequency or wavelength of the sensor being utilised. This study sought to test and compare the accuracy of modelling, in a Random Forest machine learning environment, woody above ground biomass (AGB), canopy cover (CC) and total canopy volume (TCV) in South African savannahs using a combination of X-band (TerraSAR-X), C-band (RADARSAT-2) and L-band (ALOS PALSAR) radar datasets. Training and validation data were derived from airborne LiDAR data to evaluate the SAR modelling accuracies. It was concluded that the L-band SAR frequency was more effective in the modelling of the CC (coefficient of determination or R2 of 0.77), TCV (R2 of 0.79) and AGB (R2 of 0.78) metrics in Southern African

  16. Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

    Directory of Open Access Journals (Sweden)

    Lipiński Marcin

    2016-06-01

    Full Text Available The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

  17. Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation.

    Science.gov (United States)

    Hasan, Mehedi; Maldonado-Basilio, Ramón; Hall, Trevor J

    2015-06-01

    A dual-function photonic integrated circuit for microwave photonic applications is proposed. The circuit consists of four linear electro-optic phase modulators connected optically in parallel within a generalized Mach-Zehnder interferometer architecture. The photonic circuit is arranged to have two separate output ports. A first port provides frequency up-conversion of a microwave signal from the electrical to the optical domain; equivalently single-side-band modulation. A second port provides tunable millimeter wave carriers by frequency octo-tupling of an appropriate amplitude RF carrier. The circuit exploits the intrinsic relative phases between the ports of multi-mode interference couplers to provide substantially all the static optical phases needed. The operation of the proposed dual-function photonic integrated circuit is verified by computer simulations. The performance of the frequency octo-tupling and up-conversion functions is analyzed in terms of the electrical signal to harmonic distortion ratio and the optical single side band to unwanted harmonics ratio, respectively.

  18. Control of low-frequency noise for piping systems via the design of coupled band gap of acoustic metamaterials

    Science.gov (United States)

    Li, Yanfei; Shen, Huijie; Zhang, Linke; Su, Yongsheng; Yu, Dianlong

    2016-07-01

    Acoustic wave propagation and sound transmission in a metamaterial-based piping system with Helmholtz resonator (HR) attached periodically are studied. A transfer matrix method is developed to conduct the investigation. Calculational results show that the introduction of periodic HRs in the piping system could generate a band gap (BG) near the resonant frequency of the HR, such that the bandwidth and the attenuation effect of HR improved notably. Bragg type gaps are also exist in the system due to the systematic periodicity. By plotting the BG as functions of HR parameters, the effect of resonator parameters on the BG behavior, including bandwidth, location and attenuation performance, etc., is examined. It is found that Bragg-type gap would interplay with the resonant-type gap under some special situations, thereby giving rise to a super-wide coupled gap. Further, explicit formulation for BG exact coupling is extracted and some key parameters on modulating the width and the attenuation coefficient of coupled gaps are investigated. The coupled gap can be located to any frequency range as one concerned, thus rendering the low-frequency noise control feasible in a broad band range.

  19. Analysis of dispersion and attenuation of surface waves in poroelastic media in the exploration-seismic frequency band

    Science.gov (United States)

    Zhang, Y.; Xu, Y.; Xia, J.

    2011-01-01

    We analyse dispersion and attenuation of surface waves at free surfaces of possible vacuum/poroelastic media: permeable-'open pore', impermeable-'closed pore' and partially permeable boundaries, which have not been previously reported in detail by researchers, under different surface-permeable, viscous-damping, elastic and fluid-flowing conditions. Our discussion is focused on their characteristics in the exploration-seismic frequency band (a few through 200 Hz) for near-surface applications. We find two surface-wave modes exist, R1 waves for all conditions, and R2 waves for closed-pore and partially permeable conditions. For R1 waves, velocities disperse most under partially permeable conditions and least under the open-pore condition. High-coupling damping coefficients move the main dispersion frequency range to high frequencies. There is an f1 frequency dependence as a constant-Q model for attenuation at high frequencies. R1 waves for the open pore are most sensitive to elastic modulus variation, but least sensitive to tortuosities variation. R1 waves for partially permeable surface radiate as non-physical waves (Im(k) coefficients, low Poisson's ratios, and low tortuosities increase the slope of the -f1 dependence. When the attenuation coefficients reach 0, R2 waves for partially permeable surface begin to radiate as non-physical waves. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

  20. Peak frequency in the theta and alpha bands correlates with human working memory capacity.

    Science.gov (United States)

    Moran, Rosalyn J; Campo, Pablo; Maestu, Fernando; Reilly, Richard B; Dolan, Raymond J; Strange, Bryan A

    2010-01-01

    Theta oscillations in the local field potential of neural ensembles are considered key mediators of human working memory. Theoretical accounts arising from animal hippocampal recordings propose that the phase of theta oscillations serves to instantiate sequential neuronal firing to form discrete representations of items held online. Human evidence of phase relationships in visual working memory has enhanced this theory, implicating long theta cycles in supporting greater memory capacity. Here we use human magnetoencephalographic recordings to examine a novel, alternative principle of theta functionality. The principle we hypothesize is derived from information theory and predicts that rather than long (low frequency) theta cycles, short (high frequency) theta cycles are best suited to support high information capacity. From oscillatory activity recorded during the maintenance period of a visual working memory task we show that a network of brain regions displays an increase in peak 4-12 Hz frequency with increasing memory load. Source localization techniques reveal that this network comprises bilateral prefrontal and right parietal cortices. Further, the peak of oscillation along this theta-alpha frequency axis is significantly higher in high capacity individuals compared to low capacity individuals. Importantly while we observe the adherence of cortical neuronal oscillations to our novel principle of theta functioning, we also observe the traditional inverse effect of low frequency theta maintaining high loads, where critically this was located in medial temporal regions suggesting parallel, dissociable hippocampal-centric, and prefrontal-centric theta mechanisms. PMID:21206531

  1. Peak frequency in the theta and alpha bands correlates with human working memory capacity

    Directory of Open Access Journals (Sweden)

    Rosalyn J Moran

    2010-11-01

    Full Text Available Theta oscillations in the local field potential of neural ensembles are considered key mediators of human working memory. Theoretical accounts arising from animal hippocampal recordings propose that the phase of theta oscillations serves to instantiate sequential neuronal firing to form discrete representations of items held online. Human evidence of phase relationships in visual working memory has enhanced this theory, implicating long theta cycles in supporting greater memory capacity. Here we use human magnetoencephalographic recordings to examine a novel, alternative principle of theta functionality. The principle we hypothesize is derived from information theory and predicts that rather than long (low frequency theta cycles, short (high frequency theta cycles are best suited to support high information capacity. From oscillatory activity recorded during the maintenance period of a visual working memory task we show that a network of brain regions displays an increase in peak 4-12 Hz frequency with increasing memory load. Source localization techniques reveal that this network comprises bilateral prefrontal and right parietal cortices. Further, the peak of oscillation along this theta-alpha frequency axis is significantly higher in high capacity individuals compared to low capacity individuals. Importantly while we observe the adherence of cortical neuronal oscillations to our novel principle of theta functioning, we also observe the traditional inverse effect of low frequency theta maintaining high loads, where critically this was located in medial temporal regions suggesting parallel, dissociable hippocampal-centric and prefrontal-centric theta mechanisms.

  2. Active power control with undead-band voltage & frequency droop applied to a meshed DC grid test system

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Zeni, Lorenzo; Fosso, Olav Bjarte

    2012-01-01

    for both normal and disturbed operation. Its main features are flexibility, reliability due to distributed control, easy expandability of the system and minimisation of communication needs. The control technique has been tested and its effectiveness has been verified to demonstrate its suitability......A new method for controlling active power in HVDC grids has been tested on the meshed CIGRE B4 DC grid test system. The control strategy is based on the recently proposed undead-band droop control, which combines DC voltage and AC frequency droop. It provides sufficient roomm for optimisation...

  3. New indices for quantification of the power spectrum of heart rate variability time series without the need of any frequency band definition

    International Nuclear Information System (INIS)

    This paper presents a new family of indices for the frequency domain analysis of heart rate variability time series that do not need any frequency band definition. After proper detrending of the time series, a cumulated power spectrum is obtained and frequencies that contain a certain percentage of the power below them are identified, so median frequency, bandwidth and a measure of the power spectrum asymmetry are proposed to complement or improve the classical spectral indices as the ratio of the powers of LF and HF bands (LF/HF). In normal conditions the median frequency provides similar information as the classical indices, while the bandwidth and asymmetry can be complementary measures of the physiological state of the tested subject. The proposed indices seem to be a good choice for tracking changes in the power spectrum in exercise stress, and they can guide in the determination of frequency band limits in other animal species

  4. ANALYSIS AND SOLUTION FOR MULTI-BAND ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING ULTRA WIDE BAND SYSTEM IN REAL ENVIRONMENT FOR VEHICLE TO INFRASTRUCTURE APPLICATION

    Directory of Open Access Journals (Sweden)

    Sanaa Kabil

    2013-01-01

    Full Text Available Many researches in the world deal with driving on the road to ensure optimum safety. In this context, several telecommunication technologies are often used to connect the vehicles via continuous wireless communication with the infrastructure, exchange data and information relevant to increase overall road safety and enable cooperative traffic management. These systems are not reliable for all situations and the difficulties encountered by the drivers. We have been proposed the Multi-band Orthogonal Frequency- Division Multiplexing system based on Ultra Wide Band (MB-OFDM UWB as a good candidate to insure a Vehicle to Infrastructure (V2I communication with high data rate and good performances in terms of Bit Error Rate (BER. However, Inter-Carrier Interference (ICI resulting from Doppler shift phenomenon degrades MB-OFDM UWB system performance and raises a significant challenge in wireless mobile environment. In this study, V2I communication based on the MB-OFDM UWB technology is studied and analyzed for 200 Mbit/s, over multipath channel using the IEEE802.15.4a channel model with Doppler shift for different speeds. The theoretical formulas of BER in Additive White Gaussian Noise (AWGN and Rayleigh channels are calculated and are compared to the simulation results in MB-OFDM UWB system. The comparison shows that simulation results are consistent with theoretical formulas. The degradation in the performance of the proposed system solution becomes worse with a high speed 250 Km h-1, so it’s necessary to use new receiver solutions. The Extended Kalman Filer (EKF and the Maximum Likelihood (ML estimation with ZF equalizer have been proposed and have been compared to Zero-Forcing (ZF in order to combat the ICI effect. For high value of speed (250 Km h-1, the EKF method performs better than the ML method, better than the ZF equalizer and offers much improvement in performance in term of BER.

  5. Wide operation frequency band magnetostrictive vibration power generator using nonlinear spring constant by permanent magnet

    Science.gov (United States)

    Furumachi, S.; Ueno, T.

    2016-04-01

    We study magnetostrictive vibration based power generator using iron-gallium alloy (Galfenol). The generator is advantages over conventional, such as piezoelectric material in the point of high efficiency highly robust and low electrical impedance. Generally, the generator exhibits maximum power when its resonant frequency matches the frequency of ambient vibration. In other words, the mismatch of these frequencies results in significant decrease of the output. One solution is making the spring characteristics nonlinear using magnetic force, which distorts the resonant peak toward higher or lower frequency side. In this paper, vibrational generator consisting of Galfenol plate of 6 by 0.5 by 13 mm wound with coil and U shape-frame accompanied with plates and pair of permanent magnets was investigated. The experimental results show that lean of resonant peak appears attributed on the non-linear spring characteristics, and half bandwidth with magnets is 1.2 times larger than that without. It was also demonstrated that the addition of proof mass is effective to increase the sensitivity but also the bandwidth. The generator with generating power of sub mW order is useful for power source of wireless heath monitoring for bridge and factory machine.

  6. E-beam sustained plasma as a medium for the amplification of electromagnetic radiation in the subterahertz frequency band

    International Nuclear Information System (INIS)

    It is demonstrated that low-temperature weakly-ionized nonequilibrium plasma created by a high-energy electron beam in gases (gas mixtures) with the Ramsauer minimum in a transport cross section and the effective attachment of slow electrons can be used as a medium for the amplification of electromagnetic radiation in the subterahertz frequency band. An analysis of the electron energy distribution function (EEDF) in a Xe : F2 mixture is performed. An energy interval with a growing EEDF is found to exist in such a mixture. Such an interval provides the existence of the population inversion of the electron spectrum in the continuum and is responsible for the positive value of a gain factor for microwave radiation. A gain factor depending on amplified radiation frequency and plasma parameters is analysed. (paper)

  7. An Intermediate Frequency Acquisition Scheme for S-band Single Access Link of the Tracking and Data Relay Satellite System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A nonzero intermediate frequency (IF) likelihood acquisition scheme designed for S-band Single Access (SSA) link of China's Tracking and Data Relay Satellite S y stem (CTDRSS) is introduced. The received signal is downconv erted to IF, and then direct sampled in IF using a 1-bit A/D. After the digital i zation, the sampled data is detected using a hybrid likelihood acquisition schem e. Using this structure, large noise figure of the analog mixer or active filter s, amplitude and phase imbalance between low-frequency in-phase and quandratur e- phase channel can be avoided. An easy designing algorithm of the acquisition sch eme is also derived. The performance and algorithm are verified by computer simu lation.

  8. Two-layer radio frequency MEMS fractal capacitors in PolyMUMPS for S-band applications

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    In this Letter, the authors fabricate for the first time MEMS fractal capacitors possessing two layers and compare their performance characteristics with the conventional parallel-plate capacitor and previously reported state-of-the-art single-layer MEMS fractal capacitors. Explicitly, a capacitor with a woven structure and another with an interleaved configuration were fabricated in the standard PolyMUMPS surface micromachining process and tested at S-band frequencies. The self-resonant frequencies of the fabricated capacitors were close to 10GHz, which is better than that of the parallel-plate capacitor, which measured only 5.5GHz. Further, the presented capacitors provided a higher capacitance when compared with the state-of-the-art-reported MEMS fractal capacitors created using a single layer at the expense of a lower quality factor. © 2012 The Institution of Engineering and Technology.

  9. Effects of $\\beta_{6}$ deformation and low-lying vibrational bands on heavy-ion fusion reactions at sub-barrier energies

    CERN Document Server

    Rumin, T; Takigawa, N; Rumin, Tamanna; Hagino, Kouichi; Takigawa, Noboru

    2000-01-01

    We study fusion reactions of $^{16}$O with $^{154}$Sm, $^{186}$W and $^{238}$U at sub-barrier energies by a coupled-channels framework. We focus especially on the effects of $\\beta_{6}$ deformation and low-lying vibrational excitations of the target nucleus. It is shown that the inclusion of experimental data for all of these reactions. For the $^{154}$Sm and $^{238}$U targets, the octupole vibration significantly affects the fusion barrier distribution. The effect of $\\beta$ band is negligible in all the three reactions, while the $\\gamma$ band causes a non-negligible effect on the barrier distribution at energies above the main fusion barrier. We compare the optimum values of the deformation parameters obtained by fitting the fusion data with those obtained from inelastic scatterings and the ground state mass calculations. We show that the channel coupling of high multipolarity beyond the quadrupole coupling is dominated by the nuclear coupling and hence higher order Coulomb coupling does not much influence...

  10. Narrow-band 1 W source at 257 nm using frequency quadrupled passively Q-switched Yb:YAG laser.

    Science.gov (United States)

    Goldberg, Lew; Cole, Brian; McIntosh, Chris; King, Vernon; Hays, A D; Chinn, Stephen R

    2016-07-25

    We describe generation of 1.1 W of 257 nm emission by frequency quadrupling the 1030 nm emission from a compact passively Q-switched Yb:YAG laser. The laser utilized a volume Bragg grating to achieve a 0.1 nm linewidth required for UV-Raman spectroscopic applications, generated 100 kW peak power, 250 μJ pulses and 3.6 W of average power at 1030 nm. Fourth harmonic generation (FHG) was carried out using a 10 mm lithium triborate (LBO) crystal to generate 515 nm second harmonic with 70% conversion efficiency, followed by a 7 mm beta-barium borate (BBO) crystal to generate 257 nm fourth harmonic with 45% efficiency, resulting in an overall nonlinear conversion efficiency of 31%. Far-field and near-field of the FHG emission were characterized. PMID:27464186

  11. Narrow-band 1 W source at 257 nm using frequency quadrupled passively Q-switched Yb:YAG laser.

    Science.gov (United States)

    Goldberg, Lew; Cole, Brian; McIntosh, Chris; King, Vernon; Hays, A D; Chinn, Stephen R

    2016-07-25

    We describe generation of 1.1 W of 257 nm emission by frequency quadrupling the 1030 nm emission from a compact passively Q-switched Yb:YAG laser. The laser utilized a volume Bragg grating to achieve a 0.1 nm linewidth required for UV-Raman spectroscopic applications, generated 100 kW peak power, 250 μJ pulses and 3.6 W of average power at 1030 nm. Fourth harmonic generation (FHG) was carried out using a 10 mm lithium triborate (LBO) crystal to generate 515 nm second harmonic with 70% conversion efficiency, followed by a 7 mm beta-barium borate (BBO) crystal to generate 257 nm fourth harmonic with 45% efficiency, resulting in an overall nonlinear conversion efficiency of 31%. Far-field and near-field of the FHG emission were characterized.

  12. RF-components embedded with photonic-band-bap (PBG) and fishnet-metamaterial structures for high frequency accelerator application

    CERN Document Server

    Robak, Sara; Shin, Young-Min

    2015-01-01

    In the development of high efficiency and high gradient RF-accelerators, RF waveguides and cavities have been designed with Photonic Band Gap (PBG) and fishnet- metamaterial structures. The designed structures are comprised of a periodically corrugated channel sandwiched between two photonic crystal slabs with alternating high to low dielectric constants and a multi-cell cavity-resonator designed with fishnet-metamaterial apertures. The structural designs of our interest are intended to only allow an operating-mode or -band within a narrow frequency range to propagate. The simulation analysis shows that trapped non-PBG modes are effectively suppressed down to ~ -14.3 dB/cm, while PBG modes propagated with ~2 dB of insertion loss, corresponding to ~1.14 dB/cm attenuation. The pre- liminary modeling analysis on the fishnet-embedded cavity shows noticeable improvement of Q-factor and field gradient of the operating mode (TM010) compared to those of typical pillbox- or PBG-cavities. Fabrication of the Ka-band PBG...

  13. Observation of solar radio bursts using swept-frequency radiospectrograph in 20 - 40 MHz band

    International Nuclear Information System (INIS)

    A new station for the observation of solar decametric radio bursts has been developed at Miyagi Vocational Training College in Tsukidate, Miyagi, Japan. Using the swept frequency radiospectrograph covering a frequency range from 20 MHz to 40 MHz within 200 msec, with bandwidth of 30 kHz, the radio outbursts from the sun have been currently monitored with colored dynamic spectrum display. After July 1982, successful observations provide the data which include all types of solar radio bursts such as type I, II, III, IV and V in the decametric wavelength range. In addition to these typical radio bursts, rising tone bursts with fast drift rate followed by strong type III bursts and a series of bursts repeating rising and falling tone bursts with slow drift rate have been observed. (author)

  14. An electrodeless system for measurement of liquid sample dielectric properties in radio frequency band.

    Science.gov (United States)

    Hartwig, V; Giovannetti, G; Vanello, N; Costantino, M; Landini, L; Benassi, A

    2006-01-01

    An electrodeless measurement system based on a resonant circuit is proposed for the measurement of dielectric properties of liquid samples at RF (radio frequency). Generally, properties as dielectric constant, loss factor and conductivity are measured by parallel plate capacitor cells: this method has several limitations in the case of particular liquid samples and in the range of radiofrequencies. Our method is based on the measurements of resonance frequency and quality factor of a LC resonant circuit in different measuring conditions, without and with the liquid sample placed inside a test tube around which the home made coil is wrapped. The measurement is performed using a network analyzer and a dual loop probe, inductively coupled with the resonant circuit. One of the advantages of this method is the contactless between the liquid sample and the measurement electrodes. In this paper the measurement system is described and test measurements of conventional liquids dielectric properties are reported.

  15. A reconfigurable multi-mode multi-band transmitter with integrated frequency synthesizer for short-range wireless communication

    International Nuclear Information System (INIS)

    A reconfigurable multi-mode direct-conversion transmitter (TX) with integrated frequency synthesizer (FS) is presented. The TX as well as the FS is designed with a flexible architecture and frequency plan, which helps to support all the 433/868/915 MHz ISM band signals, with the reconfigurable bandwidth from 250 kHz to 2 MHz. In order to save power and chip area, only one 1.8 GHz VCO is adopted to cover the whole frequency range. All the operation modes can be regulated in real time by configuring the integrated register-bank through an SPI interface. Implemented in 180 nm CMOS, the FS achieves a frequency coverage of 320–460 MHz and 620–920 MHz. The lowest phase noise can be −107 dBc/Hz at a 100 kHz offset and −126 dBc/Hz at a 1 MHz offset. The transmitter features a + 10.2 dBm peak output power with a +9.5 dBm 1-dB-compression point and 250 kHz/500 kHz/1 MHz/2 MHz reconfigurable signal bandwidth. (semiconductor integrated circuits)

  16. Radio wave propagation at frequencies exceeding MUF-F2 in the short wave band

    Science.gov (United States)

    Ashkaliyev, Y. F.; Bocharov, V. I.

    1972-01-01

    The results of measurements of field strength and signal/noise ratio on experimental ionospheric-scattering short wave radio links are presented. It is shown that the seasonal and diurnal variations of field strength are determined by features of solar and meteoric activity. The role of the sporadic E-layer in propagation of short radio waves at frequencies exceeding MUF-F2 is noted.

  17. Harvesting Broad Frequency Band Blue Energy by a Triboelectric-Electromagnetic Hybrid Nanogenerator.

    Science.gov (United States)

    Wen, Zhen; Guo, Hengyu; Zi, Yunlong; Yeh, Min-Hsin; Wang, Xin; Deng, Jianan; Wang, Jie; Li, Shengming; Hu, Chenguo; Zhu, Liping; Wang, Zhong Lin

    2016-07-26

    Ocean wave associated energy is huge, but it has little use toward world energy. Although such blue energy is capable of meeting all of our energy needs, there is no effective way to harvest it due to its low frequency and irregular amplitude, which may restrict the application of traditional power generators. In this work, we report a hybrid nanogenerator that consists of a spiral-interdigitated-electrode triboelectric nanogenerator (S-TENG) and a wrap-around electromagnetic generator (W-EMG) for harvesting ocean energy. In this design, the S-TENG can be fully isolated from the external environment through packaging and indirectly driven by the noncontact attractive forces between pairs of magnets, and W-EMG can be easily hybridized. Notably, the hybrid nanogenerator could generate electricity under either rotation mode or fluctuation mode to collect energy in ocean tide, current, and wave energy due to the unique structural design. In addition, the characteristics and advantages of outputs indicate that the S-TENG is irreplaceable for harvesting low rotation speeds (energy, which fits the frequency range for most of the water wave based blue energy, while W-EMG is able to produce larger output at high frequencies (>10 Hz). The complementary output can be maximized and hybridized for harvesting energy in a broad frequency range. Finally, a single hybrid nanogenerator unit was demonstrated to harvest blue energy as a practical power source to drive several LEDs under different simulated water wave conditions. We also proposed a blue energy harvesting system floating on the ocean surface that could simultaneously harvest wind, solar, and wave energy. The proposed hybrid nanogenerator renders an effective and sustainable progress in practical applications of the hybrid nanogenerator toward harvesting water wave energy offered by nature. PMID:27267558

  18. Electromagnetic characterization and shielding effectiveness of concrete composite reinforced with carbon nanotubes in the mobile phones frequency band

    Energy Technology Data Exchange (ETDEWEB)

    Micheli, D., E-mail: davide.micheli@uniroma1.it [“Sapienza” University of Rome, Department of Astronautic, Electric and Energy Engineering (DIAEE), Via Salaria 851, 00184 Rome (Italy); Pastore, R.; Vricella, A.; Morles, R.B.; Marchetti, M.; Delfini, A. [“Sapienza” University of Rome, Department of Astronautic, Electric and Energy Engineering (DIAEE), Via Salaria 851, 00184 Rome (Italy); Moglie, F.; Primiani, V. Mariani [Università Politecnica delle Marche, Department of Information Engineering (DII), Via Brecce Bianche 12, Ancona (Italy)

    2014-10-15

    Highlights: • The frequency band 0.75–1.12 GHz is exploited in mobile phone radio access network. • A lot of nanomaterial is needed for the measurement and no literature is available. • The manufacturing procedure is usually used for preparation of concrete composite. • High EM absorbing walls could be used to mitigate the human exposure to EM fields. • A shielding effectiveness of 50 dB is obtained for a 15 cm thick wall–3 wt% of CNT. - Abstract: The electromagnetic properties of carbon nanotube powder reinforced concretes are numerically and experimentally characterized. This typology of composite material is built by following the simple procedure usually adopted for the on-site concrete production. The dielectric parameters are investigated by means of waveguide measurements in the frequency band 0.75–1.12 GHz that is currently exploited in mobile phone radio access networks. The obtained results are used to compute the electromagnetic shielding effectiveness of large wall-shaped concrete structures. A shielding effectiveness up to 50 dB is obtained for a 15 cm thick wall when the carbon nanotube inclusion is raised up to 3 wt%.

  19. An Increase in Alpha Band Frequency in Resting State EEG after Electrical Stimulation of the Ear in Tinnitus Patients—A Pilot Study

    Science.gov (United States)

    Mielczarek, Marzena; Michalska, Joanna; Polatyńska, Katarzyna; Olszewski, Jurek

    2016-01-01

    In our clinic invasive transtympanal promontory positive DC stimulations were first used, with a success rate of 42%. However, non-invasive hydrotransmissive negative DC stimulations are now favored, with improvement being obtained in 37.8% directly after the treatment, and 51.3% in a follow up 1 month after treatment. The further improvement after 1 month may be due to neuroplastic changes at central level as a result of altered peripheral input. The aim of the study was to determine how/whether a single electrical stimulation of the ear influences cortical activity, and whether changes observed in tinnitus after electrical stimulation are associated with any changes in cortical activity recorded in EEG. The study included 12 tinnitus patients (F–6, M-6) divided into two groups. Group I comprised six patients with unilateral tinnitus - unilateral, ipsilateral ES was performed. Group II comprised six patients with bilateral tinnitus—bilateral ES was performed. ES was performed using a custom-made apparatus. The active, silver probe—was immersed inside the external ear canal filled with saline. The passive electrode was placed on the forehead. The stimulating frequency was 250 Hz, the intensity ranged from 0.14 to 1.08 mA. The voltage was kept constant at 3 V. The duration of stimulation was 4 min. The EEG recording (Deymed QEST 32) was performed before and after ES. The patients assessed the intensity of tinnitus on the VAS 1-10. Results: In both groups an improvement in VAS was observed—in group I—in five ears (83.3%), in group II—in seven ears (58.3%). In Group I, a significant increase in the upper and lower limit frequency of alpha band was observed in the central temporal and frontal regions following ES. These changes, however, were not correlated with improvement in tinnitus. No significant changes were observed in the beta and theta bands and in group II. Preliminary results of our research reveal a change in cortical activity after electrical

  20. Harvesting Broad Frequency Band Blue Energy by a Triboelectric-Electromagnetic Hybrid Nanogenerator.

    Science.gov (United States)

    Wen, Zhen; Guo, Hengyu; Zi, Yunlong; Yeh, Min-Hsin; Wang, Xin; Deng, Jianan; Wang, Jie; Li, Shengming; Hu, Chenguo; Zhu, Liping; Wang, Zhong Lin

    2016-07-26

    Ocean wave associated energy is huge, but it has little use toward world energy. Although such blue energy is capable of meeting all of our energy needs, there is no effective way to harvest it due to its low frequency and irregular amplitude, which may restrict the application of traditional power generators. In this work, we report a hybrid nanogenerator that consists of a spiral-interdigitated-electrode triboelectric nanogenerator (S-TENG) and a wrap-around electromagnetic generator (W-EMG) for harvesting ocean energy. In this design, the S-TENG can be fully isolated from the external environment through packaging and indirectly driven by the noncontact attractive forces between pairs of magnets, and W-EMG can be easily hybridized. Notably, the hybrid nanogenerator could generate electricity under either rotation mode or fluctuation mode to collect energy in ocean tide, current, and wave energy due to the unique structural design. In addition, the characteristics and advantages of outputs indicate that the S-TENG is irreplaceable for harvesting low rotation speeds (blue energy, while W-EMG is able to produce larger output at high frequencies (>10 Hz). The complementary output can be maximized and hybridized for harvesting energy in a broad frequency range. Finally, a single hybrid nanogenerator unit was demonstrated to harvest blue energy as a practical power source to drive several LEDs under different simulated water wave conditions. We also proposed a blue energy harvesting system floating on the ocean surface that could simultaneously harvest wind, solar, and wave energy. The proposed hybrid nanogenerator renders an effective and sustainable progress in practical applications of the hybrid nanogenerator toward harvesting water wave energy offered by nature.

  1. A Wide-Band Injection-Locked Frequency Divider in 0.18um CMOS

    OpenAIRE

    Acar, M.; Leenaerts, D. M. W.; Nauta, Bram

    2004-01-01

    In this paper we propose a novel inductorless Injection-Locked Frequency Divider (ILFD) that can make divisions with ratios 2,4,6 and 8 with wide locking ranges. Fabricated in a digital 0.18μm CMOS process the divider can operate up to 15 GHz. The measured locking ranges of the divider for division ratios 4 and 6 are 1.6 GHz and 1.1 GHz wide respectively. The current consumption of the divider is 3.8 mA operating at 1.8V supply. The active area of the chip is 100x67μm2.

  2. Design and development of precise high power wide band attenuator cum dummy load for HF and VHF frequencies

    International Nuclear Information System (INIS)

    Particle accelerators utilize high power radio frequency system to provide necessary accelerating field to charged particles for acceleration. The development of RF power sources over wide range of frequencies is in progress for various applications in accelerators. In this paper the design and indigenous development of precise low cost wide band attenuator cum dummy load has been discussed. The precise wide band attenuator/ dummy loads not merely used for absorption of RF power for testing of high power sources without any remarkable reflection but are also used for broad ranges of measurements and calibration of both active and passive RF components and devices. The ideal requirement of an attenuator/load is invariance of its resistance within specified temperature range and over wide range of supply frequencies as well as absence of any parasitic reactances. Although no practical device can meet these ideal requirements. However proper selection of design parameters and minimizing the inherent parasitic reactance and making them distributed in nature above requirements can be met satisfactorily. In order to achieve all the above requirements we have used tapered transmission line to keep both sending and receiving end impedance equal to 50 Ohm. The techniques to meet necessary requirements and practical method to realize them have been discussed in detail. The discussion about difficulties encountered and their solutions are also recommended to meet practical requirement. A 40 dB attenuator cum 50 ohm load capable of handling 1 kW input power has been already developed and tested. In this device heat is removed by natural convection. The design and development of 5 kW, 60 dB attenuator is taken care by forced convection cooling to manage thermal issue. Theoretical simulation of aforesaid attenuator had been performed with freely available software RF SIM 99 using multiple sections of lossy transmission line. To realize real practical situation hybrid analysis

  3. An advanced Ka band phased array communication system at commercial frequencies

    Science.gov (United States)

    Wald, Lawrence; Kacpura, Thomas; Kershner, Dennis

    2000-01-01

    The Glenn Research Center (GRC) Direct Data Distribution (D3) project will demonstrate an advanced, high-performance communication system that transmits information from a technology payload carried by the Space Shuttle in low-Earth orbit (LEO) to a small receiving terminal on the Earth. The Shuttle-based communications package will utilize a solid-state, Ka-band phased array antenna that electronically steers the 19.05 Ghz RF signal toward a low-cost, tracking ground terminal, thereby providing agile, vibration-free, electronic steering at reduced size and weight with increased reliability. The project will also demonstrate new digital modulation and processing technology that will allow transmission of user/platform data at rates up to 1200 Mbits per second. This capability will enable the management of the substantially increased amounts of data to be collected from the International Space Station (ISS) or other LEO platforms directly to NASA field centers, principal investigators, or into the commercial terrestrial communications network. .

  4. A low power wide-band CMOS PLL frequency synthesizer for portable hybrid GNSS receiver

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shimao; Yu Yunfeng; Ma Chengyan; Ye Tianchun [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Yin Ming, E-mail: xiaoshimao@casic.ac.c [Hangzhou Zhongke Microelectronics Co Ltd, Hangzhou 310053 (China)

    2010-03-15

    The design consideration and implementation of a CMOS frequency synthesizer for the portable hybrid global navigation satellite system are presented. The large tuning range is achieved by tuning curve compensation using an improved VCO resonant tank, which reduces the power consumption and obtains better phase noise performance. The circuit is validated by simulations and fabricated in a standard 0.18 {mu}m 1P6M CMOS process. Close-loop phase noise measured is lower than -95 dBc at 200 kHz offset while the measured tuning range is 21.5% from 1.47 to 1.83 GHz. The proposed synthesizer including source coupled logic prescaler consumes 6.2 mA current from 1.8 V supply. The whole silicon required is only 0.53 mm{sup 2}. (semiconductor integrated circuits)

  5. Experimental estimations of viscoelastic properties of multilayer damped plates in broad-band frequency range

    CERN Document Server

    Ege, Kerem; Laulagnet, Bernard; Guyader, Jean-Louis

    2012-01-01

    Regarding lightweighting structures for aeronautics, automotive or construction applications, the level of performance of solutions proposed in terms of damping and isolation is fundamental. Hence multilayered plate appears as an interesting answer if damping performances are properly optimized. In this paper, a novel modal analysis method (Ege et al, JSV 325 (4-5), 2009) is used to identify viscoelastic properties (loss factors, Young's modulus) of "polyethylene thermoplastic / aluminum" bilayer plates. The thermoplastic is chosen for its high loss factors and relative low mass. The experimental method consists in a high-resolution technique (ESPRIT algorithm) which allows precise estimations of the viscoelastic properties even in frequency domains with high modal overlap (high damping or modal density). Experimental loss factors estimated from impact hammer excitations on the free-free plates highly corresponds with two theoretical estimations. In the first model (Guyader & Lesueur, JSV 58(1), 1978) the...

  6. AxiSEM and instaseis: Fast simulation of global wavefields across the frequency band

    Science.gov (United States)

    Nissen-Meyer, T.; van Driel, M.; Krischer, L.; Stähler, S. C.; Hosseini, K.; Leng, K.

    2015-12-01

    We present our seismic modeling methods AxiSEM and instaseis. These methods exploit recent developments in high-performance computing and suitable numerical methods for seismic wave propagation, while operating efficiently across the vast observable frequency spectrum of global waves in sparse yet realistic structures. AxiSEM (www.axisem.info and geodynamics.org) relies upon axisymmetric (including spherically symmetric) models, thereby satisfying a large fraction of observable data. The benefit of this method lies in the resultant dimensional collapse to two numerical dimensions, whereby the third azimuthal dimension is tackled analytically. For high-frequency wave propagation, this leads to 3-4 orders of magnitude speedup in computational cost compared to 3D domain discretizations. AxiSEM is highly scalable and accommodates efficient implementations of viscoelasticity and anisotropy. We will present benchmarks, data comparisons, a diverse range of applications from inner-core anisotropy to noise modeling and lowermost mantle structures, and wavefields for sensitivity kernels. We also touch upon ongoing efforts for linking computational cost to structural complexity in the vein of Occam's razor, eventually allowing for an adaptive rendition of 1D, 2D and 3D structures at optimally low computational cost, as well as 1D/3D hybrid approaches. Instaseis (www.instaseis.net) is a methodology to extract full, broadband and accurate waveforms instantaneously from wavefield databases computed with AxiSEM. This "once-and-for-all solution" relies on reciprocity and requires only two AxiSEM simulations to construct the databases, while allowing for arbitrary parameter changes (e.g. source, processing, structure) instantaneously with modest computational cost and storage requirements. The instaseis python package is integrated with ObsPy, contains a graphical user interface, and can be used for source inversion, noise simulations, finite-fault modeling, waveform tomography

  7. Note: radio frequency inductance-capacitance band-stop filter circuit to perform contactless conductivity measurements in pulsed magnetic fields.

    Science.gov (United States)

    Altarawneh, M M

    2012-09-01

    We present a new technique to perform radio frequency (rf) contactless conductivity measurements in pulsed magnetic fields to probe different ground states in condensed matter physics. The new method utilizes a simple analog band-stop filter circuit implemented in a radio frequency transmission setup to perform contactless conductivity measurements. The new method is more sensitive than the other methods (e.g., the tunnel diode oscillator and the proximity detector oscillator) due to more sensitive dependence of the circuit resonance frequency on the tank circuit inductance (not the transmission line). More important, the new method is more robust than other methods when used to perform measurements in very high magnetic fields, works for a wide range of temperatures (i.e., 300 K-1.4 K) and is less sensitive to noise and mechanical vibrations during pulse magnet operation. The new technique was successfully applied to measure the Shubnikov-de Haas effect in Bi(2)Se(3) in pulsed magnetic fields of up to 60 T.

  8. Note: Radio frequency inductance-capacitance band-stop filter circuit to perform contactless conductivity measurements in pulsed magnetic fields

    Science.gov (United States)

    Altarawneh, M. M.

    2012-09-01

    We present a new technique to perform radio frequency (rf) contactless conductivity measurements in pulsed magnetic fields to probe different ground states in condensed matter physics. The new method utilizes a simple analog band-stop filter circuit implemented in a radio frequency transmission setup to perform contactless conductivity measurements. The new method is more sensitive than the other methods (e.g., the tunnel diode oscillator and the proximity detector oscillator) due to more sensitive dependence of the circuit resonance frequency on the tank circuit inductance (not the transmission line). More important, the new method is more robust than other methods when used to perform measurements in very high magnetic fields, works for a wide range of temperatures (i.e., 300 K-1.4 K) and is less sensitive to noise and mechanical vibrations during pulse magnet operation. The new technique was successfully applied to measure the Shubnikov-de Haas effect in Bi2Se3 in pulsed magnetic fields of up to 60 T.

  9. Nicotine induction of theta frequency oscillations in rodent medial septal diagonal band in vitro

    Institute of Scientific and Technical Information of China (English)

    Cheng-biao LU; Cheng-zhang LI; Dong-liang LI; Zaineb HENDERSON

    2013-01-01

    Aim:This study aimed to examine the role of the nicotinic receptor (nAChR) in the generation of theta oscillations (4-12 Hz) in vitro.Methods:Electrophysiological studies were performed on medial septal diagonal band area (MSDB) slices to measure theta oscillation.Immunofluorescence and confocal microscopy studies were carried out to detect α4 nAChR and β2 nAChR subunits in perfused-fixed tissue from VGluT2-GFP and GAD67-GFP transgenic mice.Results:Application of nicotine to MSDB slices produced persistent theta oscillations in which area power increased in a doseresponsive manner.This activity was inhibited by GABAA receptor antagonists and partially by ionotropic glutamate receptor antagonists,indicating the involvement of local GABAergic and glutamatergic neurons in the production of the rhythmic activity.The nicotineinduced theta activity was also inhibited selectively by non-α7*nAChR antagonists,suggesting the presence of these receptor types on GABAergic and glutamatergic neuron populatjons in the MSDB.This was confirmed by immunofluorescence and confocal microscopy studies in transgenic mice in which the GABAergic and glutamatergic neurons express green fluorescent protein (GFP),showing Iocalisation of β2 nAChR and α4 nAChR subunits,the most common constituents of non-α7*nAChRs,in both cell types in the MSDB.Conclusion:Theta activity in the MSDB may be generated by tonic stimulation of non-α7*nAChRs.

  10. Characteristics of Alpha Band Frequency in Adolescents with Bipolar II Disorder: A Resting-State QEEG Study.

    Directory of Open Access Journals (Sweden)

    Mahdi Moeini

    2015-03-01

    Full Text Available The aim of this study was to compare the QEEG of adolescents affected by bipolar II disorder with age and gender matched healthy controls, and to extract the characteristics of the alpha frequency band to better understand this disorder.Twenty one adolescents affected by acute episodes of bipolar II disorder (BMD II, both hypomanic and depressive episodes, were selected via convenience sampling based on DSM IV criteria and child and adolescent psychiatrist diagnosis. Eleven patients were going through a hypomanic episode and 10 patients were going through a depression episode. Of the participants, 18 who were matched with the patient group participated in this study as a normal group. Any major comorbidities and intellectual disabilities were excluded through applying K-SADS-PL and Raven's IQ test for all the patients and the healthy participants. Electroencephalogram signals were obtained according to 10-20 international system by 21 electrodes from participants in open and closed eyes in a resting state. We selected 40 seconds length segments from each recorded EEG signals that had minimal noise and artifacts. Power spectrum density (PSD was estimated for each segment and extracted alpha band frequency. We used only referential (unipolar montage for comparison. Eventually, data were analyzed by independent Mann-Whitney test and independent t test.We observed significant differences in the alpha frequency band in some brain regions. Alpha power increased in the fronto-central region and right parietal lobe in the patients (P < 0.05. In the patients with BMD II, entropy of alpha oscillations was larger than the normal participants in the central region and in the F3, F4 and P4 channels. Also, there were differences in the variance of alpha oscillations in these regions between the two groups (P < 0.05. In the occipital lobe, alpha wave had different skewness between the two groups (P < 0.05.Thalamus as a generator and modulator of at least a

  11. Targeted high and low speech frequency bands to right and left ears respectively improve task performance and perceived sociability in dyadic conversations.

    Science.gov (United States)

    Gregory, Stanford W; Kalkhoff, Will; Harkness, Sarah K; Paull, Jessica L

    2009-07-01

    Past research shows that the lower nonverbal frequencies of the human voice, beneath .5 kHz, transmit an acoustic signal promoting social convergence and status accommodation between human interlocutors. We conducted a laboratory experiment and a validation study to explore the possible communications benefits of targeting the low-frequency band to the left ears of human participants and the high-frequency band to the right ears. We compare this "Enhanced" condition with two other conditions: a "Confounded" condition, in which the low-frequency band was targeted to participants' right ears and the higher-frequency band to their left ears; and a Control condition, in which the entire unaltered frequency band was targeted to both ears. For the duration of their interaction, experiment participants engaged in dyadic conversations while attempting to complete a task via an audio-visual communication system. Our results show that both the speed and accuracy of task completion were significantly improved in the Enhanced condition. In the second validation study, groups of participants rated the quality of videotaped conversations from the experiment using a semantic differential instrument. The Enhanced condition conversations were rated significantly more affectively favourable than either the unaltered Control or Confounded condition conversations. Overall, our results exhibit potential for enhancing two-way electronic communications and improving task performances in media environments.

  12. Targeted high and low speech frequency bands to right and left ears respectively improve task performance and perceived sociability in dyadic conversations.

    Science.gov (United States)

    Gregory, Stanford W; Kalkhoff, Will; Harkness, Sarah K; Paull, Jessica L

    2009-07-01

    Past research shows that the lower nonverbal frequencies of the human voice, beneath .5 kHz, transmit an acoustic signal promoting social convergence and status accommodation between human interlocutors. We conducted a laboratory experiment and a validation study to explore the possible communications benefits of targeting the low-frequency band to the left ears of human participants and the high-frequency band to the right ears. We compare this "Enhanced" condition with two other conditions: a "Confounded" condition, in which the low-frequency band was targeted to participants' right ears and the higher-frequency band to their left ears; and a Control condition, in which the entire unaltered frequency band was targeted to both ears. For the duration of their interaction, experiment participants engaged in dyadic conversations while attempting to complete a task via an audio-visual communication system. Our results show that both the speed and accuracy of task completion were significantly improved in the Enhanced condition. In the second validation study, groups of participants rated the quality of videotaped conversations from the experiment using a semantic differential instrument. The Enhanced condition conversations were rated significantly more affectively favourable than either the unaltered Control or Confounded condition conversations. Overall, our results exhibit potential for enhancing two-way electronic communications and improving task performances in media environments. PMID:19031308

  13. A second mutation associated with apparent [beta]-hexosaminidase A pseudodeficiency: Identification and frequency estimation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Z.; Chabot, T.; Triggs-Raine, B.L. (Univ. of Manitoba, Winnepeg (Canada)); Natowicz, M.R.; Prence, E.M. (Shriver Center for Mental Retardation, Waltham, MA (United States) Harvard Medical School, Boston, MA (United States)); Kaback, M.M.; Lim-Steele, S.T.; Brown, D. (Children' s Hospital, San Diego, CA (United States) Univ. of California, San Diego, CA (United States))

    1993-12-01

    Deficient activity of [beta]-hexosaminidase A (Hex A), resulting from mutations in the HEXA gene, typically causes Tay-Sachs disease. However, healthy individuals lacking Hex A activity against synthetic substrates (i.e., individuals who are pseudodeficient) have been described. Recently, an apparently benign C[sub 739]-to-T (Arg247Trp) mutation was found among individuals with Hex A levels indistinguishable from those of carriers of Tay-Sachs disease. This allele, when in compound heterozygosity with a second [open quotes]disease-causing[close quotes] allele, results in Hex A pseudodeficiency. The authors examined the HEXA gene of a healthy 42-year-old who was Hex A deficient but did not have the C[sub 739]-to-T mutation. The HEXA exons were PCR amplified, and the products were analyzed for mutations by using restriction-enzyme digestion or single-strand gel electrophoresis. A G[sub 805]-to-A (Gly269Ser) mutation associated with adult-onset G[sub m2] gangliosidosis was found on one chromosome. A new mutation, C[sub 745]-to-T (Arg 249Trp), was identified on the second chromosome. This mutation was detected in an additional 4/63 (6%) non-Jewish and 0/218 Ashkenazi Jewish enzyme-defined carriers. Although the Arg249Trp change may result in a late-onset form of G[sub M2] gangliosidosis, any phenotype must be very mild. This new mutation and the benign C[sub 739]-to-T mutation together account for [approximately]38% of non-Jewish enzyme-defined carriers. Because carriers of the C[sub 739]-to-T and C[sub 745]-to-T mutations cannot be differentiated from carriers of disease-causing alleles by using the classical biochemical screening approaches, DNA-based analyses for these mutations should be offered for non-Jewish enzyme-defined heterozygotes, before definitive counseling is provided. 46 refs., 5 figs., 2 tabs.

  14. Mobile Communication Networks and Digital Television Broadcasting Systems in the Same Frequency Bands – Advanced Co-Existence Scenarios

    Directory of Open Access Journals (Sweden)

    L. Polak

    2014-04-01

    Full Text Available The increasing demand for wireless multimedia services provided by modern communication systems with stable services is a key feature of advanced markets. On the other hand, these systems can many times operate in a neighboring or in the same frequency bands. Therefore, numerous unwanted co-existence scenarios can occur. The aim of this paper is to summarize our results which were achieved during exploration and measurement of the co-existences between still used and upcoming mobile networks (from GSM to LTE and digital terrestrial television broadcasting (DVB systems. For all of these measurements and their evaluation universal measurement testbed has been proposed and used. Results presented in this paper are a significant part of our activities in work package WP5 in the ENIAC JU project “Agile RF Transceivers and Front-Ends for Future Smart Multi-Standard Communications Applications (ARTEMOS”.

  15. Negative refraction and subwavelength imaging of a photonic-crystal slab for the frequencies in the third band

    Institute of Scientific and Technical Information of China (English)

    Shuai Feng; Cheng Ren; Degang Xu; Yiquan Wang

    2009-01-01

    Negative refraction and subwavelength imaging properties of a two-dimensional(2D)photonic crystal(PC)slab are studied by the finite-difference time-domain method.The PC consists of a triangular lattice of air holes immersed in a dielectric.For a certain frequency range in the third photonic band,the directions of the group velocities and the phase velocities can be opposite,so the PC can work as a kind of negative refractive-index material.The light radiated from a point source can form a subwavelength image spot through the PC slab.Negative refraction and an effective refractive index of the PC slab n=-1 can be achieved for the incident wave with its incident angle within a certain range.

  16. Broadband tunable Raman soliton self-frequency shift to mid-infrared band in a highly birefringent microstructure fiber

    Science.gov (United States)

    Wei, Wang; Xin-Ying, Bi; Jun-Qi, Wang; Yu-Wei, Qu; Ying, Han; Gui-Yao, Zhou; Yue-Feng, Qi

    2016-07-01

    Raman soliton self-frequency shifted to mid-infrared band (λ > 2 μm) has been achieved in an air-silica microstructure fiber (MF). The MF used in our experiment has an elliptical core with diameters of 1.08 and 2.48 μm for fast and slow axis. Numerical simulation shows that each fundamental orthogonal polarization mode has two wide-spaced λ ZDW and the λ ZDW pairs located at 701/2110 nm and 755/2498 nm along the fast and slow axis, respectively. Using 810-nm Ti:sapphire femtosecond laser as pump, when the output power varies from 0.3 to 0.5 W, the furthest red-shift Raman solitons in both fast and slow axis shift from near-infrared band to mid-infrared band, reaching as far as 2030 and 2261 nm. Also, mid-infrared Raman solitons can always be generated for pump wavelength longer than 790 nm if output pump power reaches 0.5 W. Specifically, with pump power at 0.5 W, the mid-infrared soliton in slow axis shifts from 2001 to 2261 nm when the pump changes from 790 nm to 810 nm. This means only a 20 nm change of pump results in 260 nm tunability of a mid-infrared soliton. Project supported by the National Natural Science Foundation of China (Grant Nos. 61405172, 61405173, and 61275093), the Natural Science Foundation of Hebei Province, China (Grant No. F2014203194), the College Science Research Program of Hebei Province, China (Grant No. QN20131044), and the Program of Independent Research for the Young Teachers of Yanshan University of China (Grant No. 13LGB017).

  17. A Novel Characteristic Frequency Bands Extraction Method for Automatic Bearing Fault Diagnosis Based on Hilbert Huang Transform

    Directory of Open Access Journals (Sweden)

    Xiao Yu

    2015-11-01

    Full Text Available Because roller element bearings (REBs failures cause unexpected machinery breakdowns, their fault diagnosis has attracted considerable research attention. Established fault feature extraction methods focus on statistical characteristics of the vibration signal, which is an approach that loses sight of the continuous waveform features. Considering this weakness, this article proposes a novel feature extraction method for frequency bands, named Window Marginal Spectrum Clustering (WMSC to select salient features from the marginal spectrum of vibration signals by Hilbert–Huang Transform (HHT. In WMSC, a sliding window is used to divide an entire HHT marginal spectrum (HMS into window spectrums, following which Rand Index (RI criterion of clustering method is used to evaluate each window. The windows returning higher RI values are selected to construct characteristic frequency bands (CFBs. Next, a hybrid REBs fault diagnosis is constructed, termed by its elements, HHT-WMSC-SVM (support vector machines. The effectiveness of HHT-WMSC-SVM is validated by running series of experiments on REBs defect datasets from the Bearing Data Center of Case Western Reserve University (CWRU. The said test results evidence three major advantages of the novel method. First, the fault classification accuracy of the HHT-WMSC-SVM model is higher than that of HHT-SVM and ST-SVM, which is a method that combines statistical characteristics with SVM. Second, with Gauss white noise added to the original REBs defect dataset, the HHT-WMSC-SVM model maintains high classification accuracy, while the classification accuracy of ST-SVM and HHT-SVM models are significantly reduced. Third, fault classification accuracy by HHT-WMSC-SVM can exceed 95% under a Pmin range of 500–800 and a m range of 50–300 for REBs defect dataset, adding Gauss white noise at Signal Noise Ratio (SNR = 5. Experimental results indicate that the proposed WMSC method yields a high REBs fault

  18. Low-frequency waves in a high-beta collisionless plasma: polarization, compressibility and helicity

    International Nuclear Information System (INIS)

    The linear theory of waves near and below the ion cyclotron frequency in an isothermal electron-ion Vlasov plasma which is isotropic, homogeneous and magnetized is considered. Numerical solutions of the full dispersion equation for the magnetosonic whistler and Alfven/ion cyclotron modes at βsub(i)=1.0 are presented, and the polarizations, compressibilities, helicities, ion Alfven ratios and ion cross-helicities are exhibited and compared. At sufficiently large βsub(i) and theta, the angle of propagation with respect to the magnetic field, the real part of the polarization of the Alfven/ion cyclotron wave changes sign, so that, for such parameters, this mode is no longer left-hand polarized. The Alfven/ion cyclotron mode becomes more compressive as the wavenumber increases, whereas the magnetosonic/whistler becomes more compressive with increasing theta. At oblique propagation, the helicity of both modes approaches zero in the long-wavelength limit; in contrast, the ion cross-helicity is of order unity for the Alfven/ion cyclotron wave and decreases as theta increases for the magnetosonic/whistler mode. (author)

  19. Rejection of radio-frequency noise with a wide-band differential preamplifier and solid-shielded coaxial input cables

    International Nuclear Information System (INIS)

    Radio-frequency signals simulating electrical interference ranging from 50 Hz to 50 MHz were applied to the shields of the input cable system (two solid-shielded, mineral-insulated cables approximately 6 m long) of a wide-band (approximately 60 MHz) differential preamplifier for use with fission counters as input devices as part of in-vessel, low-level flux monitors in future liquid-metal fast breeder reactors (LMFBRs) to determine the common-mode rejection. Results show that differences in electrical properties and shielding characteristics of the two input coaxial cables along with end effects produced by an unbalanced sensor severely degrade the rejection capability of the differential preamplifier. At 1 MHz, the common-mode rejection without input cables is approximately -70 dB; this is reduced to approximately -10 dB when measured with the rf signal applied to the surface of the input cable shields. Measurements of the shielding characteristics of the input cables showed resonances at test frequencies greater than 2 MHz. A ferrite core was installed in the input assembly to increase the impedance of the shields and to permit termination of the coaxial line consisting of the input cable shields and the protective metal conduit for the input cables. This assembly eliminated all resonances below 20 MHz. The increased impedance also reduced the amplitude of the shield currents, resulting in an increase in the shielding effectiveness of the input cables without affecting the signal transmission of the cables

  20. 高低频复合基板研究%Composite Substrate with Wide Frequency Band from DC to RF

    Institute of Scientific and Technical Information of China (English)

    王栋; 林玉敏; 季兴桥

    2011-01-01

    Mixed-signal composite substrate offers signal transmission with a wide frequency range from DC to RF. Both challenges of manufacturing this substrate and its main attributes Were introduced. Composite substrate with a wide frequency band from DC to RF can ba fabricated in three ways: composite construction of FR4 PCB and microwave multilayer printed circuits, low temperature co-fired ceramics and liquid-crystal-polymer, which are introduced in detail.%高低频复合基板技术是在同一块基板上同时实现低频信号和高频信号的传输.主要介绍了高低频复合基板制造面临的挑战以及高低频复合基板的主要特性.较为详细地介绍了高低频复合基板主要的三种实现方式,即FR4印制电路板与微波印制电路的复合结构、低温共烧陶瓷技术以及液晶聚合物基板.

  1. Frequency band-dependence of S-wave splitting in China mainland and its implications

    Institute of Scientific and Technical Information of China (English)

    LIU; Kun

    2001-01-01

    [1]Liu, T. S., Loess and the Environment, Beijing: China Ocean Press, 1985, 1-251.[2]Chen, L. X., Zhu, Q. G., Luo, H. B. et al., East Asian Monsoon, Beijing: China Meteorology Press, 1991, 28-61.[3]An, Z. S., Liu, T. S., Lu, Y. C. et al., The long-term palaeomonsoon variation recorded by the loess-palaeosol sequence in central China, Quaternary International, 1990, (7/8): 91-95.[4]Guo, Z. T., Liu, T. S., Fedoroff, N. et al., Shift of the monsoon intensity on the Loess Plateau at ca. 0.85 MaBP, Chinese Science Bulletin, 1993, 38(2): 586-591.[5]Chen, J., An, Z. S., Wang, Y. J. et al., Distributions of Rb and Sr in the Luochuan loess-paleosol sequence of China during the last 800 ka: Implications for paleomonsoon variations, Science in China, Ser. D, 1999, 42(3): 225-232.[6]Chen, J., Wang, Y. J., Ji, J. F. et al., Rb/Sr variations and its climatic stratigraphical significance of a loess-paleosol profile from Luochuan, Shaanxi Province, Quaternary Sciences (in Chinese), 1999, 19(4): 350-356.[7]Guo, Z. T.,Liu, T. S., Fedoroff, N. et al., Climate extremes in loess of China coupled with the strength of deep-water for-mation in the North Atlantic, Global and Planetary Change, 1998, 18: 113-128.[8]Guo, Z. T., Liu, T. S., An, Z. S., Paleosols of the last 0.15 Ma in the Weinan loess section and their paleoclimate signifi-cance, Quaternary Sciences (in Chinese), 1994, 14(3): 256-269.[9]Guo, Z, T,, Fedoroff, N., Liu, T. S., Micromorphology of the loess-paleosol sequence of the last 130 ka in China and pa-leoclimatic event, Science in China (in Chinese), Ser. D, 1996, 26(3): 392-398.[10]Guo, Z., Liu, T., Guiot, J., et al., High frequency pulses of East Asian monsoon climate in the last two glaciations: Link with the North Atlantic, Climate Dynamics, 1996, 12: 701-709.[11]Guo, Z. T., Peng, S. Z., Wei, L. Y. et al., Weathering signals of Millennial-Scale oscillations of the East Asian Summer monsoon over the last 220 ka, Chinese Science

  2. The giant frequency shift of intramolecular O-H vibration band in the raman spectra of water on the silver surface

    CERN Document Server

    Kompan, Mikhail

    2016-01-01

    The giant frequency shift was observed in Raman spectra for inramolecular O-H vibration band. The effect was observed in SERS-condition experiment, when exciting light was focused by short-focus objective on the Ag-surface, merged in water. The shift was detected relatively to the regularl position of band, measured from the bulk of water under the same other conditions.

  3. Microbial resistance and frequency of extended-spectrum beta-lactamase (ESBL in isolated from blood cultures

    Directory of Open Access Journals (Sweden)

    Ruan Carlos Gomes da Silva

    2014-12-01

    Full Text Available Introduction:The emergence and spread of isolated carriers of extended-spectrum beta-lactamase (ESBL have complicated the treatment of nosocomial infections, since its production is not easily identified by the sensitivity tests, routinely performed in clinical laboratories, leading to difficulties in the hospital control of resistant microorganisms and antibiotics misuse.Objective:The objective of this study was to analyze the resistance profile and the frequency of ESBL in Gram-negative bacteria isolated from blood cultures. A hundred bacterial samples from blood cultures of adult patients were analyzed, which were phenotypically identified by biochemical tests of carbohydrates fermentation and submitted to determination of the resistance profile by disc diffusion test and ESBL screening by disc approximation and disc replacement methods.Results:Among the bacterial samples tested, 30 were identified as Gram-negative bacteria, predominantly by Proteus mirabilis, Pantoea agglomerans, and Escherichia coli. Of these, 73.33% were positive for the detection of ESBL by phenotypic tests, and was found mainly in Pantoea agglomerans, Proteus mirabilis, and Enterobacter cloacae.Conclusion:The increase in the occurrence of ESBL in different Enterobacteriaceae shows the importance of the amplification of detection in other species than Escherichia coli or Klebsiella sp., so that the assistance to the patient is not restrained, since these resistant bacteria cannot be detected by the laboratories. Considering the frequency of ESBL in this study, we highlight the importance of its detection, aiming to its contribution to the development of improvements in the health care policies of hospitals.

  4. The Frequency of Extended-spectrum Beta-lactamase and The Rate of Antibiotic Resistance in Escherichia coli Strains

    Directory of Open Access Journals (Sweden)

    Gul Karagoz

    2013-06-01

    Full Text Available Background The resistance related with production of extended-spectrum beta-lactamase (ESBL is an important problem that we face when we are treating infections caused by enterobacteriaceae. We aimed to evaluate the frequency of ESBL production in E. coli strains and the rate of antibiotic resistance isolated from in our microbiology laboratory. Method E. coli strains isolated from various clinical specimens between January 2010 – December 2011 were assessed retrospectively. Resistances to ESBL-producing and non-producing E. coli and the rate of ESBL production according to the years were investigated. The results were compared with statistical analysis. Results The rate of ESBL producing E. coli was 21.9% in 2010, and 25% in 2011. There was no resistance to imipenem, meropenem, ertapenem and tigecycline in all strains. The resistance to antibiotics other than amikacin was statistically significant in ESBL producing E. coli compared to ESBL non-producing E.coli (p<0.05. Conclusion Surveillance studies guide appropriate antibiotic therapy and prevent development of resistance. Empiric treatment should be started according to local surveillance data, and de-escalation of the administered antibiotics should be used following culture results. [TAF Prev Med Bull 2013; 12(3.000: 291-296

  5. A novel wideband, low-profile and second-order miniaturized band-pass frequency selective surfaces

    Directory of Open Access Journals (Sweden)

    Nianxi Xu

    2015-07-01

    Full Text Available A novel wideband, low-profile and second-order miniaturized band-pass frequency selective surface (FSS made of metallic mesh and its complementary structures with skewed arrays of modified triples is presented in this paper. Compared with traditional second-order bandpass FSSs obtained using λ/4 apart from one another, the novel FSS with an overall thickness of λ/18 is composed of three metallic layers (the outside and middle layers are complementary separated by two electric thin dielectric substrates. This arrangement can shorten the inter-element spacing and increase the bandwidth, while the up and bottom metallic layers can constitute a symmetric biplanar FSS and thus realize ability of maximally flat second-order bandpass response. The novel FSS has a −3 dB bandwidth about 8.2 GHz (6.9 -15.1 GHz and a fractional bandwidth exceeds 75%. Moreover, such an FSS has the merits of stable performance for incident angles within 50° and different polarizations. The principles of operation along with guidelines for the design of the proposed FSS, the simulated results by vector modal matching method, and the experimental values of the fabricated prototype are also presented and discussed.

  6. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  7. Detection of shallow buried nonmetallic landmine and estimation of its depth at microwave X-band frequency

    Science.gov (United States)

    Tiwari, K. C.; Singh, D.; Arora, M.

    2009-05-01

    Current methods of demining are mostly ground or vehicle based and therefore extremely time consuming, risky and also do not produce low false alarm rates. Detection of landmines using airborne and satellite based sensors are a viable risk free alternative. However extracting mine like features from data captured using airborne and satellite based sensors using signal and image processing techniques with low false alarm rates is a subject of active research. Microwave remote sensing in X-band (10 GHz, 3 cm) frequency has the capability for both subsurface penetration and resolution of landmines as well as non-lethal targets. In the present study, a set of experiments under laboratory conditions have been carried out using dummy landmines without explosives buried to different depths up to 10 cm in dry smooth sand. The data generated through the experiments is processed through a series of image processing steps and a region of interest segmented using Otsu and Maximum Entropy based thresholding methods. The region of interest is masked and the average observed backscatter containing the mine further processed through an electromagnetic model developed and optimized using genetic algorithm for estimation of depth. The method does not have any requirement of separate training and test data set to train the optimizer and validate the results. The results under laboratory conditions indicate satisfactory results both for detection of shallow buried landmines and estimation of depth.

  8. A pseudogap model beyond BCS for the cuprates: The effect of order parameter symmetry, Debye frequency and band structure

    International Nuclear Information System (INIS)

    One of the most intriguing aspects of high temperature superconductors (HTSC) is the presence of the pseudogap in the normal and the superconducting phases of the cuprate compounds. Several pseudogap models have been proposed to explain the $abnormal$ properties of the cuprates. One of the recent models relies on the assumption that the self-energy is given by ΣPG(iωn)=- Eg2(k)G0(k,-iωn) where G0(k,iωn is the one- particle free Green function. Going beyond this mean field model for the pseudogap we now take into account fluctuations of the pseudogap as ΣPG(iωn)=- Eg2(k)GPG(k,-iωn) where GPG(k,iωn is the one-particle full Green function. We study the combined effect of the band structure and the Debye frequency, ωD, on the superconducting critical temperature, Tc, as a function of the number of carriers per site, n. Our conclusions are: 1) increasing the value of V/t increases the value of Tc/t; 2) increasing the value of EG/t decreases the value of Tc/t. By the way, one needs some critical value of V/t to have finite values of Tc/t. This is the reason we have taken high values of V/ to find superconductivity; 3) decreasing the value of ωD/t decreases the value of Tc/t. This is reasonable since we have less available states around the Fermi; 4) the inclusion of α', which we call the effect of the band structure, is important because it moves the center of curve of Tc/t x n. The center of this curve, with respect to half-filling (n=1), is displaced to the left if α'>0.0; 5) the chemical potential is defined in the region where Tc/t ≠ 0. However, in this region, it is almost identical for different values of V/t. This is due to the fact that μ is a global property; 6) our model always produces d-wave superconductivity around the Fermi level, independent whether EG(K-bar)/t is s- or d-wave symmetry. (author)

  9. Frequency and intensity dependence of the sub-band-gap features observed in the surface photovoltage spectrum of semi-insulating GaAs

    Science.gov (United States)

    Sharma, T. K.; Kumar, Shailendra; Rustagi, K. C.

    2002-11-01

    Surface photovoltage spectroscopy studies on thick semi-insulating GaAs wafers are reported in the range 850-950 nm using the chopped light geometry. We observed some interesting sharp features in the sub-band-gap of SI-GaAs, which were reported recently [Appl. Phys. Lett. 79, 1715(2001); Rev. Sci. Instrum. 73, 1835 (2002)]. In this article, we present the dependence of these features on the chopping frequency and the source intensity. The intensity variation in the above-band-gap region and for the A peak (898 nm) in the sub-band-gap region could be fitted with single component while it is necessary to consider more than one component to fit the data for the Q peak (887 nm) in the sub-band-gap region. A model consistent with the observed features is also proposed.

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

    Science.gov (United States)

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

    2014-05-01

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

  11. New generation chiral metamaterials with small and flat chirality over a certain frequency band based on circular split ring resonators for microwave filter applications

    Science.gov (United States)

    Dincer, Furkan; Akgol, Oguzhan; Karaaslan, Muharrem; Unal, Emin; Demirel, Ekrem; Sabah, Cumali

    2016-02-01

    There are many studies in literature on chiral metamaterials (MTMs) to obtain large chiralities with dynamic optical activities. With this regard, this new generation planar chiral MTM study focuses on a small, non-dispersive (constant/flat) chirality admittance over an indicated frequency band which has not been investigated so far in literature. This new generation planar chiral MTM provides a small and a constant/fixed chirality which is mostly ignored by the scientists. This study numerically and experimentally investigates and examines these new generation MTMs based on circular split ring resonators (SRRs) with an increased capacitance in details. Obtained results show that the suggested structure can provide a small and constant/flat chirality admittance over a certain frequency band and hence it can be used to design myriad novel electromagnetic (EM) devices such as transmission and antireflection filters, polarization rotators for any desired frequency regions.

  12. Pre-treatment with beta blockers and the frequency of hypokalaemia in patients with acute chest pain.

    OpenAIRE

    Simpson, E; Rodger, J C; Raj, S. M.; Wong, C.; Wilkie, L; Robertson, C.

    1987-01-01

    Plasma potassium concentration was measured at admission in 1234 patients who presented with acute chest pain. One hundred and ninety five patients were on beta blockers before admission. The potassium concentrations of patients admitted early (within four hours of onset of symptoms) were compared with those admitted later (4-18 hours after onset of symptoms). There was a transient fall in plasma potassium concentrations in patients not pre-treated with beta blockers. This was not seen in pat...

  13. Low-loss transmission band in photonic crystal waveguides with sharp cutoff at a frequency below the bandgap

    DEFF Research Database (Denmark)

    Krüger, Asger Christian; Zhang, Min; Groothoff, Nathaniel;

    2011-01-01

    We present TE transmission measurements of photonic crystal waveguides with high hole radius to period ratio r/Λ=0.388. This geometry introduces a unique low loss transmission band in addition to the traditional PhC guiding band and very sharp transmission edges for devices with a length of 50 μm...... or longer. Finite difference time domain and plane wave expansion simulations confirm the results and show that the sharpness of the cutoffs can be explained by the spectral shape of the guiding mode in the band diagram....

  14. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    Science.gov (United States)

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light.

  15. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    Science.gov (United States)

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light. PMID:18084457

  16. A broad slow frequencies band and high slowing down factor by using one-dimensional hybrid periodic/Fibonacci photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ali, N; Kanzari, M, E-mail: naimgi2@yahoo.fr [Photovoltaic and Semiconductor Materials Laboratory, El-Manar University-ENIT PO Box 37, Le belvedere 1002-Tunis (Tunisia)

    2010-11-15

    By using a theoretical model based on Transfer Matrix Method (TMM) for normal incidence simulator, and for serial (S) polarisation, the slowing of light in one-dimensional (1D) hybrid (Fibonacci{sub 1}/periodic/Fibonacci{sub 2}) photonic crystals is studied at visible frequency band. Effects of the periodicity, the non-periodicity and the number of layers of each photonic structure on the slowing down of light are discussed. The higher slowing down factors was obtained by the hybrid Fibonacci{sub 1}/periodic/Fibonacci{sub 2} structures. This slowing down factors is greater than those corresponding to the periodic, the Fibonacci, the Thue-Morse and the Cantor band-gap structures. In addition this hybrid structure gives the possibility to slowing several frequencies

  17. Development of a 7.2-, 8.4-, and 32- Gigahertz (X-/X-/Ka-Band) Three-Frequency Feed for the Deep Space Network

    Science.gov (United States)

    Stanton, P. H.; Hoppe, D. J.; Reilly, H.

    2001-01-01

    This article summarizes the design of a three-frequency feed for the Deep Space Network supporting the 32-GHz downlink, 8.4-GHz downlink, and 7.2-GHz uplink bands simultaneously. Monopulse tracking is also provided at 32 GHz. The design combines high-power uplink operation and ultra-low-noise receive capability in a single feed with no need for frequency-selective surfaces or external diplexers. The key components of the feed will be described along with special considerations taken into account during their design. Experimental results, lessons learned, and ideas for future improvement are also included.

  18. Peculiarities of Forming Single-Frequency Generation in a Monopulse YAG:Nd-Laser with Transverse Diode Pumping and Injection of Narrow-Band Radiation

    Science.gov (United States)

    Bogdanovich, M. V.; Kalinov, V. S.; Kostik, O. E.; Lantsov, K. I.; Lepchenkov, K. V.; Mashko, V. V.; Ryabtsev, A. G.; Ryabtsev, G. I.; Teplyashin, L. L.

    2016-05-01

    The features of forming output radiation in a powerful monopulse single-frequency side diode-pumped laser operating in external narrow-band signal seeding mode were investigated. The monopulse single-frequency laser was fabricated of a YAG:Nd active element excited by three laser diode matrices. A compact continuous-wave YAG:Nd-laser with longitudinal diode pumping served as the seeding laser. It was shown experimentally that the transition of the monopulse laser from multimode to single-frequency lasing with a spectral line width of about 54 MHz (0.2 pm) occurs at seeding-laser radiation power P th ≈ 0.14 mW (radiation intensity of 1.8·10-2 W/cm2). Increasing the seeding-laser power over P th does not lead to a noticeable change of the output characteristics of the monopulse laser for a given pump level (above the threshold). If the pump power varies from 1.5 to 3.0 kW, the P th value is not changed but the energy of the output pulses of single-frequency monopulse generation increases to 40 MJ. The low level of the external narrow-band seeding signal allows us to consider the single-frequency low-power semiconductor laser as a promising source of the seeding signal.

  19. Pupil Dilation and EEG Alpha Frequency Band Power Reveal Load on Executive Functions for Link-Selection Processes during Text Reading.

    Directory of Open Access Journals (Sweden)

    Christian Scharinger

    Full Text Available Executive working memory functions play a central role in reading comprehension. In the present research we were interested in additional load imposed on executive functions by link-selection processes during computer-based reading. For obtaining process measures, we used a methodology of concurrent electroencephalographic (EEG and eye-tracking data recording that allowed us to compare epochs of pure text reading with epochs of hyperlink-like selection processes in an online reading situation. Furthermore, this methodology allowed us to directly compare the two physiological load-measures EEG alpha frequency band power and pupil dilation. We observed increased load on executive functions during hyperlink-like selection processes on both measures in terms of decreased alpha frequency band power and increased pupil dilation. Surprisingly however, the two measures did not correlate. Two additional experiments were conducted that excluded potential perceptual, motor, or structural confounds. In sum, EEG alpha frequency band power and pupil dilation both turned out to be sensitive measures for increased load during hyperlink-like selection processes in online text reading.

  20. Digital Predistortion of 75-110GHzW-Band Frequency Multiplier for Fiber Wireless Short Range Access Systems

    DEFF Research Database (Denmark)

    Zhao, Ying; Pang, Xiaodan; Deng, Lei;

    2011-01-01

    We present a digital predistortion technique to effectively compensate high nonlinearity of a sextuple multiplier operating at 99.6GHz. An 18.9dB adjacent-channel power ratio (ACPR) improvement is guaranteed and a W-band fiber-wireless system is experimentally investigated.......We present a digital predistortion technique to effectively compensate high nonlinearity of a sextuple multiplier operating at 99.6GHz. An 18.9dB adjacent-channel power ratio (ACPR) improvement is guaranteed and a W-band fiber-wireless system is experimentally investigated....

  1. The non-equilibrium response of a superconductor to pair-breaking radiation measured over a broad frequency band

    International Nuclear Information System (INIS)

    We have measured the absorption of terahertz radiation in a BCS superconductor over a broad range of frequencies from 200 GHz to 1.1 THz, using a broadband antenna-lens system and a tantalum microwave resonator. From low frequencies, the response of the resonator rises rapidly to a maximum at the gap edge of the superconductor. From there on, the response drops to half the maximum response at twice the pair-breaking energy. At higher frequencies, the response rises again due to trapping of pair-breaking phonons in the superconductor. In practice, this is a measurement of the frequency dependence of the quasiparticle creation efficiency due to pair-breaking in a superconductor. The efficiency, calculated from the different non-equilibrium quasiparticle distribution functions at each frequency, is in agreement with the measurements

  2. Measurements of pressure induced self-broadening and frequency shift coefficients of methane R9 manifold of 2v3 band

    Institute of Scientific and Technical Information of China (English)

    Weiguang Ma; Lei Dong; Wangbao Yin; Linfeng Li; Lei Zhang; Suotang Jia

    2005-01-01

    @@ An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2v3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm-1 were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232±0.003 and 0.0055±0.0007 MHz/Pa, respectively.

  3. 基于ECG频带特征的身份识别%A Human Identification Method Based on ECG's Frequency Band Features

    Institute of Scientific and Technical Information of China (English)

    王利; 白鹏飞; 潘中良; 易子川

    2012-01-01

    目的:心电图作为活体的生理信号,可以方便的从手指中提取,具备易采集、难复制的特点.因此,本文提出了基于单导联ECG频带特征的身份识别方法.方法:文中首先对单周期ECG进行小波包变换,提取各子带的波形与能量,并将子带能量、ECG波形、子带波形作为分类特征;然后,引入DTW算法确定待测数据与模板之间的ECG波形、子带波形的最优匹配距离,同时提取待测数据与模板之间的子带能量比值与差值,为上述参数设置合适阈值并进行身份识别.结果:当测试数据与模板取自同一样本时,同频带的子带能量、ECG波形、子带波形差异较小,所以同一子带能量之比接近于1,同一子带的能量之差与波形的匹配距离接近于0.反之,上述参数差异较大,这为ECG提供了良好的分类特征.结论:将ECG用于身份识别,识别装置的硬件成本低,并且用于识别的信号难以窃取,是一种比较安全的身份识别手段.实验结果表明,相较传统算法,本文提出的方法具有较高识别率,这为ECG身份识别提供了一种新的方法.%Objective: As a physiological signal in vivo, ECG (electrocardiogram) can be easily extracted from fingers. It is easy to collect but difficult to replicate. Therefore, the paper proposed a human identification method based on frequency band features of single lead ECG. Methods: Firstly, decomposition of the single-cycle ECG signal is proposed by using wavelet packet and the waveform and energy of each sub-band is extracted. It uses the sub-band energy.the ECG waveform,the sub-band waveform as classification features; Then, the DTW algorithm is introduced to determine the optimal matching distance of ECG waveforms and sub-band waveforms between test data and the template. The research extracts the energy ratio and difference of each sub-band between test data and the template at the same time. It sets suitable thresholds for above parameters for

  4. Exploration of multi-fold symmetry element-loaded superconducting radio frequency structure for reliable acceleration of low- & medium-beta ion species

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shichun [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2015-09-01

    Reliable acceleration of low- to medium-beta proton or heavy ion species is needed for future high-current superconducting radio frequency (SRF) accelerators. Due to the high-Q nature of an SRF resonator, it is sensitive to many factors such as electron loading (from either the accelerated beam or from parasitic field emitted electrons), mechanical vibration, and liquid helium bath pressure fluctuation etc. To increase the stability against those factors, a mechanically strong and stable RF structure is desirable. Guided by this consideration, multi-fold symmetry element-loaded SRF structures (MFSEL), cylindrical tanks with multiple (n>=3) rod-shaped radial elements, are being explored. The top goal of its optimization is to improve mechanical stability. A natural consequence of this structure is a lowered ratio of the peak surface electromagnetic field to the acceleration gradient as compared to the traditional spoke cavity. A disadvantage of this new structure is an increased size for a fixed resonant frequency and optimal beta. This paper describes the optimization of the electro-magnetic (EM) design and preliminary mechanical analysis for such structures.

  5. Frequency reconfigurable of three-band RF MEMS PIFA antenna%RF MEMS频率可重构三频PIFA天线的设计

    Institute of Scientific and Technical Information of China (English)

    胡芳菲; 许高斌; 陈兴; 马渊明

    2016-01-01

    设计了一种结合RF MEMS开关实现频率可重构的三频PIFA(planner inverted F-antenna,平面倒F天线)天线。该频率可重构天线通过变换在地层的RF MEMS开关的通断改变天线的谐振回路的物理长度,从而改变PIFA天线的工作频率。通过HFSS仿真可知,这个天线可以工作在203,498和910 MHz这三个频率为中心的频段,其相对带宽分别为18%,10%和8%,能够满足实际通信的需求。%The frequency reconfigurable three-band planner inverted F-antenna(PIFA) that employed RF mico-electro-mechanical systems (RF MEMS) switches was designed. The frequency reconfigurable antenna was achieved by using RF MEMS switches on the ground to change the physical lengths of the paths on the antenna resonance circuit, and then to change the antenna’s work frequency. Simulation was conducted by HFSS. Results denote this antenna can work centered around 203, 498, 910 MHz three bands and has the relative bandwidths of 18%, 10% and 8%, respectively, and it can meet the needs of practical communication.

  6. Qualitative Analysis of the Time-Frequency Signature Induced by a Reflected L-Band Signal from Time Evolving Sea Surfaces

    CERN Document Server

    Coatanhay, Arnaud

    2013-01-01

    Passive remote sensing techniques have become more and more popular for detection and characterization purposes. The advantage of using the Global Navigation Satellite Systems (GNSS) are the well known signals emitted and the availability in most areas on Earth. In the present paper, L-Band signals (including GNSS signals) are considered for oceanographic purposes. The main interest in this contribution is the analysis of the signal reflected by an evolving sea surface using time-frequency transforms. The features which occur in this domain are examined in relation to the physical phenomena: interaction of the electromagnetic waves with the moving sea surface.

  7. Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector

    OpenAIRE

    Hernandez-Garcia, C.; Kraslinikov, M.; Asova, G.; Bakr, M; Boonpornprasert, P.; Good, J; GROSS, M; Huck, H.; Isaev, I.; Kalantaryan, D.; Khojoyan, M.; Kourkafas, G.; Lishilin, O.; Malyutin, D.; Melkumyan, D.

    2016-01-01

    This paper discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency cavity (RF gun) from Cs2Te photocathodes illuminated with ps-long UV laser pulses when the laser transverse distribution consists of a flat-top core with Gaussian-like decaying halo. The produced charge shows a linear dependence at low laser pulse energies as expected in the quantum efficiency limited emission regime, while its dependence on laser pulse energy is observed to be m...

  8. Analysis of eigenfrequencies of finite periodic structures in view of location of frequency pas- and stop-bands

    DEFF Research Database (Denmark)

    Hvatov, Alexander; Sorokin, Sergey

    2013-01-01

    cell with various boundary conditions. Two classical models of periodic structures are considered, for which closed form solutions are obtained and analyzed. The regular and irregular eigenfrequencies of periodicity cells and finite periodic structures are identified, and the eigenmodes are compared....... application, however, only a finite segment of such a structure can be used. This paper is concerned with comparison of the eigenfrequency spectra of finite periodic structures with location of stop-bands for their infinite counterparts. Special attention is paid to eigenfrequencies of a single periodicity...

  9. Over-the-horizon propagation measurements at six radar-frequency bands at the Atlantic Ocean Coast

    Science.gov (United States)

    Boekema, R. B.

    1993-07-01

    In the autumn of 1989, the propagation subgroup of NATO AC/243 has conducted a propagation experiment near Lorient France, at the Atlantic Ocean. The purpose of this experiment was to gain an insight into the influence of the evaporation duct above the sea on the propagation of radar signals of different frequencies in an over-the-horizon situation and into the applicability of model predictions. The geometry of the experiment has been chosen to represent a typical ship defence situation. The measurements have shown that for the present case the nearly always present evaporation duct results in a signal enhancement with the strongest effects at the 10.5 and 16 GHz frequencies. An extended study of the quality of the model predictions, possible by the unique set of measurement results, shows some interesting matters. If the process of prediction is divided into two parts, the calculation of the duct height from the meteorological data and the path loss calculation from this duct height, the conclusion is made that the first part is responsible for the largest inaccuracies. The used duct height calculation method showed systematic deviations for different meteorological conditions. The inaccuracy of the duct height calculation makes useful path loss predictions at the millimeter-wave frequencies (35 and 94 GHz) impossible for this over-the-horizon situation. The predictions at the lower frequencies are much better, but not always satisfactory. The deviation analyses in this report can be useful to improve propagation models.

  10. Multi-band radio over fiber system with all-optical halfwave rectification, transmission and frequency down-conversion

    DEFF Research Database (Denmark)

    Prince, Kamau; Tafur Monroy, Idelfonso

    2011-01-01

    We introduce a novel application of all-optical half-wave rectification in the transportation and delivery of multi-frequency radio-over fiber signals. System evaluation was performed of transmission over various optical fiber types and all-optical envelope detection was implemented to achieve...

  11. An equivalent roughness model for seabed backscattering at very high frequencies using a band-matrix approach

    DEFF Research Database (Denmark)

    Wendelboe, Gorm; Jacobsen, Finn; Bell, Judith

    2007-01-01

    This work concerns modeling of very high frequency (>100 kHz) sonar images obtained from a sandy seabed. The seabed is divided into a discrete number of 1D height profiles. For each height profile the backscattered pressure is computed by an integral equation method for interface scattering between...

  12. EFFECT OF BUMP WIDTH ON THE EFFICIENCY OF HIGH-LOW 4H-SIC IMPATT AT Ka-BAND WINDOW FREQUENCY

    Directory of Open Access Journals (Sweden)

    SOUMEN BANERJEE,

    2010-10-01

    Full Text Available The effect of bump width on the efficiency of high-low p+nn-n+ single drift 4H-SiC Impatt diode has been investigated at Ka-band (35 GHz window frequency. A drift diffusion model has been used to study theparameters at optimum bias current density. The diode is designed to operate at millimeter wave frequency. The highest efficiency obtained is found to be at and around 25.47% if the high-to-low doping ratio is varied from 1000 to 50 for a fixed n layer width of 0.8 μm. The conversion efficiency is found to be higher at lower bump width for small doping density ratio. As the doping density is increased the peak efficiency is found to shift towards higher bump width.

  13. 33 W quasi-continuous-wave narrow-band sodium D2a laser by sum-frequency generation in LBO

    Science.gov (United States)

    Wang, Peng-Yuan; Xie, Shi-Yong; Bo, Yong; Wang, Bao-Shan; Zuo, Jun-Wei; Wang, Zhi-Chao; Shen, Yu; Zhang, Feng-Feng; Wei, Kai; Jin, Kai; Xu, Yi-Ting; Xu, Jia-Lin; Peng, Qin-Jun; Zhang, Jing-Yuan; Lei, Wen-Qiang; Cui, Da-Fu; Zhang, Yu-Dong; Xu, Zu-Yan

    2014-09-01

    We demonstrate an all-solid quasi-continuous-wave (QCW) narrow-band source tunable to sodium D2a line at 589.159 nm. The source is based on sum-frequency mixing between lasers at 1064 nm and 1319 nm in a LBO crystal. The 1064 nm and 1319 nm lasers are produced from two diode side-pumped Nd:YAG master oscillator power amplifier (MOPA) laser systems, respectively. A 33 W output of 589 nm laser is obtained with beam quality factor M2 = 1.25, frequency stability better than ±0.2 GHz and linewidth less than 0.44 GHz. A prototype 589 nm laser system is assembled, and a sodium laser guided star has been successfully observed in the field test.

  14. 宽带频率选择表面带阻滤波器的优化设计%The Design of Wide-Band Band-Stop Filter with Frequency Selective Surfaces Hexagon Array

    Institute of Scientific and Technical Information of China (English)

    张蒙; 骆兴芳; 张芳

    2015-01-01

    现代通信需要宽带频率选择表面( Frequency Selective Surfaces,FSS)滤波器的应用。利用六边形阵列良好的宽带特性,设计了一款带宽达到7 GHz以上的多层FSS滤波器结构,设计采用优化算法差分进化( differential Evolution,DE)算法,谱域矩量法用来分析FSS结构的频率响应,仿真结果显示该结构具有良好的角度和极化稳定性,为高带宽的通信需求提供了数据参考。%The application of wide-band frequency selective surfaces( FSS)filter is required in modern communica-tion. A multi-layered hexagon FSS array which has more than 7 GHz bandwidth is presented by employing the good wide characteristics of hexagon array. The optimization algorithm,the differential Evolution( DE)is employed and the frequency response of FSS structure is analyzed by the spectral domain Method of Moments( MoM). The simula-ted results demonstrate that the proposed structure has the good stability of angle and polarization which provide the reference data for wide-bandtelecommunication.

  15. Research of the smart frequency adjustable bands RFID reader%一款灵巧宽频带RFID读写器研究

    Institute of Scientific and Technical Information of China (English)

    张朋; 范福玲; 常静; 杨益

    2015-01-01

    针对各种RFID标签工作频段不尽相同,技术标准不一致,而传统RFID读写器工作频带很窄且不支持多协议,造成对标签读取不便的问题,研究和设计了对多频段、多协议的电子标签兼容的RFID读写器。提出读写器工作频率可调和多通信协议的解决方案;在系统硬件中,微控制器采用ST公司的STM32 F103 VET6芯片,以TI公司低成本但配置灵活的CC1101作为射频收发模块;设计了频率可调的匹配网络;在软件上实现了读写器支持多种通信协议的功能。另外,还对具有尺寸缩减作用的弯折线偶极子天线设计做了仿真研究。该读写器具有适应性强,成本低等特点,给RFID的应用带来了便捷。%The frequency bands and the technical standards of the RFID tags are often different, and the RFID reader often has very narrow operating frequency bands and can’t support mutl-protocal, which will cause problems when the RFID reader read the data from the RFID tags. To overcome this problem, a smart multi-frequency bands and multi-protocol RFID reader is research and designed. The system scheme of the adjustable operating frequency and the multi-protocol of the RFID reader is proposed. In the hardware system, the ST’s STM32F103VET6 chips and the TI’s CC1101 chips are selected to configu-rated as the mcu and RF transceiver modules. The adjustable frequency matching network is also de-signed, and the multi-protocol functions are realized in the software system. In addition, the bending wire dipole antenna is studied and simulated to reduce the size of the antenna. The reader has a strong adapta-bility, low cost, which can bring the convenience of RFID applications.

  16. Quantification of magnetic nanoparticles with broad-band-frequency magnetic susceptibility measurements: a case study of an upper loess/palaeosol succession at Luochuan, Chinese Loess Plateau

    Science.gov (United States)

    Kodama, Kazuto; An, Zhisheng; Chang, Hong; Qiang, Xiaoke

    2014-11-01

    Broad-band magnetic susceptibility (MS) measurement, a novel magnetic method capable of quantifying a narrow grain size distribution (GSD) of superparamagnetic (SP) particles by measuring low-field MS at a number of frequency steps spanning four orders of magnitude, has been tested in a loess/palaeosol section at Luochuan in the Chinese Loess Plateau. The studied succession consists of sequences from the latest palaeosol unit (S0) to the upper part of the loess unit (L2), spanning the last glacial-interglacial cycle. Reconstructed GSDs consist of volume fractions on the order of 10-24 m3, and the mean GSDs are modal but with distinctive skewness among the loess, the weakly developed palaeosols (weak palaeosols), and the mature palaeosols. This indicates that the mean volume of SP particles in this loess/palaeosol sequence tends to increase during the transition from loess → weak palaeosol → palaeosol, an indication of grain growth as pedogenesis progresses. Total frequency dependence, or TFD(per cent), the difference between χ130 at the lowest (130 Hz) and χ500k at the highest (500 kHz) frequencies normalized to χ130, is judged to be a more suitable index than previous frequency dependence parameters for the concentration of SP particles. TFD(per cent) has a strong correlation with χ130, showing a continuous `growth curve' with the rate of increase being highest for the loess, moderate for the weak palaeosols, and saturated for the palaeosols. The characteristic curve suggests that smaller SP particles are preferentially formed in the earlier stage of pedogenesis rather than the later phase when even larger particles are formed in mature palaeosols. These results demonstrate that the broad-band MS measurement method will be useful for the quantitative assessment of magnetic nanoparticles in soils and sediments.

  17. A 220–1100 MHz low phase-noise frequency synthesizer with wide-band VCO and selectable I/Q divider

    International Nuclear Information System (INIS)

    This paper presents a low phase-noise fractional-N frequency synthesizer which provides an in-phase/quadrature-phase (I/Q) signal over a frequency range of 220–1100 MHz for wireless networks of industrial automation (WIA) applications. Two techniques are proposed to achieve the wide range. First, a 1.4–2.2 GHz ultralow gain voltage-controlled oscillator (VCO) is adopted by using 128 tuning curves. Second, a selectable I/Q divider is employed to divide the VCO frequency by 2 or 3 or 4 or 6. Besides, a phase-switching prescaler is proposed to lower PLL phase noise, a self-calibrated charge pump is used to suppress spur, and a detect-boosting phase frequency detector is adopted to shorten settling time. With a 200 kHz loop bandwidth, lowest measured phase noise is −106 dBc/Hz at a 10 kHz offset and −131 dBc/Hz at a 1 MHz offset. Fabricated in the TSMC 0.18 μm CMOS process, the synthesizer occupies a chip area of 1.2 mm2, consumes only 15 mW from the 1.8 V power supply, and settles within 13.2 μs. The synthesizer is optimized for the WIA applications, but can also be used for other short-range wireless communications, such as 433, 868, 916 MHz ISM band applications. (semiconductor integrated circuits)

  18. Progress towards fabrication of Th:229-doped high energy band-gap crystals for use as a solid-state optical frequency reference

    CERN Document Server

    Rellergert, Wade G; DeMille, D; Greco, R R; Hehlen, M P; Jackson, R A; Torgerson, J R; Hudson, Eric R

    2010-01-01

    We have recently described a novel method for the construction of a solid-state optical frequency reference based on doping $^{229}$Th into high energy band-gap crystals. Since nuclear transitions are far less sensitive to environmental conditions than atomic transitions, we have argued that the $^{229}$Th optical nuclear transition may be driven inside a host crystal resulting in an optical frequency reference with a short-term stability of $3\\times10^{-17}<\\Delta f/f <1\\times10^{-15}$ at 1 s and a systematic-limited repeatability of $\\Delta f/f \\sim 2 \\times 10^{-16}$. Improvement by $10^2-10^3$ of the constraints on the variability of several important fundamental constants also appears possible. Here we present the results of the first phase of these experiments. Specifically, we have evaluated several high energy band-gap crystals (Th:NaYF, Th:YLF, Th:LiCAF, Na$_2$ThF$_6$, LiSAF) for their suitability as a crystal host by a combination of electron beam microprobe measurements, Rutherford Backscatte...

  19. The distribution of spectral index of magnetic field and ion velocity in Pi2 frequency band in BBFs: THEMIS statistics

    Science.gov (United States)

    Wu, Q.; Du, A. M.; Volwerk, M.; Wang, G. Q.

    2016-09-01

    A statistical study of the THEMIS FGM and ESA data is performed on turbulence of magnetic field and velocity for 218 selected 12 min intervals in BBFs. The spectral index α in the frequency range of 0.005-0.06 Hz are Gaussian distributions. The peaks indexes of total ion velocity Vi and parallel velocity V‖ are 1.95 and 2.07 nearly the spectral index of intermittent low frequency turbulence with large amplitude. However, most probable α of perpendicular velocity V⊥ is about 1.75. It is a little bigger than 5/3 of Kolmogorov (1941). The peak indexes of total magnetic field BT is 1.70 similar to V⊥. Compression magnetic field B‖ are 1.85 which is smaller than 2 and bigger than 5/3 of Kolmogorov (1941). The most probable spectral index of shear B⊥ is about 1.44 which is close to 3/2 of Kraichnan (1965). Max V⊥ have little effect on the power magnitude of VT and V‖ but is positively correlated to spectral index of V⊥. The spectral power of BT, B‖ and B⊥ increase with max perpendicular velocity but spectral indexes of them are negatively correlated to V⊥. The spectral index and the spectral power of magnetic field over the frequency interval 0.005-0.06 Hz is very different from that over 0.08-1 Hz.

  20. Beta频段双耳差频声刺激对大脑生理状态的影响%Effects of Beta Band Binaural Beats on Brain Physiological Status

    Institute of Scientific and Technical Information of China (English)

    张露; 焦学军; 高翔; 陈润格; 王学民; 綦宏志; 明东; 何峰; 周鹏

    2016-01-01

    随着载人航天事业的快速发展,航天员的大脑状态调控以及警觉度提高技术成为航天人因工程研究热点和难点问题之一。为了探究beta段差频声刺激对大脑状态的调控作用,在N⁃back任务过程中进行了beta段双耳差频声刺激组和对照组平行实验。根据实验中的N⁃back反应时和正确率分类,划分成三组对beta频段差频声刺激敏感程度不同的受试人群,分别是敏感组、中间组和非敏感组,分析beta频段功率谱密度差值、( alpha+theta)/beta的比值、非线性特征样本熵和互信息脑网络等特征。结果表明,双耳差频声刺激的脑区激活存在个体差异性,对声刺激敏感的受试者,差频刺激下,脑电功率谱中的beta频段在右颞区能量增强( T4,p<0�005),T3电极处三组人群(alpha+theta)/beta比值具有显著差异性,敏感人群中刺激组样本熵值比对照组高10�53%,且互信息集群系数最高(0�971),脑网络信息交流增强,这说明差频声刺激能改变大脑的生理状态,在提高航天员的注意力和警觉度、对抗脑力疲劳方面具有应用前景。%With the rapid development of manned space program, exploring new methods to improve the brain physiological status effectively and rapidly is one of the hottest researches in the area of space human factors engineering. Binaural beat is a kind of acoustic stimulus mode, which is closely related to the features of human brain waves, mental state and mood. In order to explore its correla⁃tion with the brain status, two sets of parallel experiments were designed for the beta band binaural frequency stimulus group and the contrast group. According to the reaction time and accuracy rate of N⁃back, subjects who had different sensitive degree to sound stimulus were classified into three dif⁃ferent groups:sensitivity group, middle group and non⁃sensitivity group. In the

  1. Probing the Orientation and Conformation of alpha-Helix and beta-Strand Model Peptides on Self-Assembled Monolayers Using Sum Frequency Generation and NEXAFS Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weidner, T.; Apte, J; Gamble, L; Castner, D

    2010-01-01

    The structure and orientation of amphiphilic {alpha}-helix and {beta}-strand model peptide films on self-assembled monolayers (SAMs) have been studied with sum frequency generation (SFG) vibrational spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The {alpha}-helix peptide is a 14-mer, and the {beta}-strand is a 15-mer of hydrophilic lysine and hydrophobic leucine residues with hydrophobic periodicities of 3.5 and 2, respectively. These periodicities result in the leucine side chains located on one side of the peptides and the lysine side chains on the other side. The SAMs were prepared from the assembly of either carboxylic acid- or methyl-terminated alkyl thiols onto gold surfaces. For SFG studies, the deuterated analog of the methyl SAM was used. SFG vibrational spectra in the C-H region of air-dried peptides films on both SAMs exhibit strong peaks near 2965, 2940, and 2875 cm{sup -1} related to ordered leucine side chains. The orientation of the leucine side chains was determined from the phase of these features relative to the nonresonant gold background. The relative phase for both the {alpha}-helix and {beta}-strand peptides showed that the leucine side chains were oriented away from the carboxylic acid SAM surface and oriented toward the methyl SAM surface. Amide I peaks observed near 1656 cm{sup -1} for the {alpha}-helix peptide confirm that the secondary structure is preserved on both SAMs. Strong linear dichroism related to the amide {pi}* orbital at 400.8 eV was observed in the nitrogen K-edge NEXAFS spectra for the adsorbed {beta}-strand peptides, suggesting that the peptide backbones are oriented parallel to the SAM surface with the side chains pointing toward or away from the interface. For the {alpha}-helix the dichroism of the amide {pi}* is significantly weaker, probably because of the broad distribution of amide bond orientations in the {alpha}-helix secondary structure.

  2. High-frequency magnetic stimulation attenuates beta-amyloid protein 1-42 neurotoxicity in organotypic hippocampal slices

    Institute of Scientific and Technical Information of China (English)

    Don-Kyu Kim; Young Chul Yoon; Soo Ahn Chae; Kyung Mook Seo; Tai Ryoon Han; Si-Hyun Kang

    2010-01-01

    Repetitive transcranial magnetic stimulation(rTMS)has been utilized as a therapeutic tool for neurodegenerative disorders including Alzheimer's disease.However,the precise mechanisms of its clinical effects remain unknown.β-amyloid(Aβ)exhibits direct neurotoxic effects and is closely related to neuronal degeneration in Alzheimer's disease.Therefore,it has been hypothesized that the neuroprotective effects of rTMS are related to the mechanisms of protection against Aβneurotoxicity.Organotypic hippocampal slices were prepared from 8-day old,Sprague Dawley rats.The tissue slices were exposed to 100 μmol/L Aβ1-42 since day 12 in vitro with and without high-frequency(20 Hz)magnetic stimulation.Magnetic stimulation efficacy was evaluated by measuring neuronal nuclei(NeuN)protein expression and by observing cultures following propidium iodide fluorescence staining and bromodeoxyuridine(BrdU)immunohistochemistry.Lactate dehydrogenase activity was detected in the culture media to evaluate hippocampal neuronal damage.Our results demonstrated that high-frequency magnetic stimulation significantly reversed the reduction of NeuN protein expression because of Aβ1-42 exposure(P < 0.05)and significantly reduced the number of damaged cells in the hippocampal slices(P < 0.05).However,lactate dehydrogenase levels and anti-BrdU staining results did not reveal any statistical differences.These findings indicate that high-frequency magnetic stimulation might have protective effect on hippocampal neurons from Aβ1-42 neurotoxicity.

  3. Study of the dielectric parameters of aluminium ore bauxite of Mainpat area of Chhattisgarh at X-band frequency

    Indian Academy of Sciences (India)

    S K Srivastava; B R Vishwakarama

    2004-08-01

    A simple method for measuring the dielectric parameter of materials in the form of powders at microwave frequencies is suggested. Measurement of the permittivity $\\varepsilon'$ and $\\varepsilon''$ at 9.967 GHz on powder samples of the aluminum ore bauxite gives interesting results. It is found that $\\varepsilon'$ and $\\varepsilon''$ increases with packing densities(). Further $\\varepsilon'$ and $\\varepsilon''$ also depend upon the percentage of Al23. These results show that the values of $\\varepsilon'$ and $\\varepsilon''$ can be used to set certain basic values for minability of the ore for a particular sample. Conductivities () and relaxation () are also calculated in the present studies.

  4. A joint resonance frequency estimation and in-band noise reduction method for enhancing the detectability of bearing fault signals

    Science.gov (United States)

    Bozchalooi, I. Soltani; Liang, Ming

    2008-05-01

    The vibration signal measured from a bearing contains vital information for the prognostic and health assessment purposes. However, when bearings are installed as part of a complex mechanical system, the measured signal is often heavily clouded by various noises due to the compounded effect of interferences of other machine elements and background noises present in the measuring device. As such, reliable condition monitoring would not be possible without proper de-noising. This is particularly true for incipient bearing faults with very weak signature signals. A new de-noising scheme is proposed in this paper to enhance the vibration signals acquired from faulty bearings. This de-noising scheme features a spectral subtraction to trim down the in-band noise prior to wavelet filtering. The Gabor wavelet is used in the wavelet transform and its parameters, i.e., scale and shape factor are selected in separate steps. The proper scale is found based on a novel resonance estimation algorithm. This algorithm makes use of the information derived from the variable shaft rotational speed though such variation is highly undesirable in fault detection since it complicates the process substantially. The shape factor value is then selected by minimizing a smoothness index. This index is defined as the ratio of the geometric mean to the arithmetic mean of the wavelet coefficient moduli. De-noising results are presented for simulated signals and experimental data acquired from both normal and faulty bearings with defective outer race, inner race, and rolling element.

  5. A compact frequency selective stop-band splitter by using Fabry-Perot nanocavity in a T-shaped waveguide

    Institute of Scientific and Technical Information of China (English)

    M Afshari Bavil; Sun Xiu-Dong

    2013-01-01

    By utilizing a Fabry-Perot (FP) nanocavity adjacent to T-shaped gap waveguide ports,spectrally selective filtering is realized.When the wavelength of incident light corresponds to the resonance wavelength of the FP nanocavity,the surface plasmons are captured inside the nanocavity,and light is highly reflected from this port.The resonance wavelength is determined by using Fabry-Perot resonance condition for the nanocavity.For any desired filtering frequency the dimension of the nanocavity can be tailored.The numerical results are based on the two-dimensional finite difference time domain simulation under a perfectly matched layer absorbing boundary condition.The analytical and simulation results indicate that the proposed structure can be utilized for filtering and splitting applications.

  6. Feeding at a high pitch: Source parameters of narrow band,high-frequency clicks from echolocating off-shore hourglassdolphins and coastal Hector's dolphins

    DEFF Research Database (Denmark)

    Kyhn, Line Anker; Tougaard, Jakob; Jensen, Frants Havmand;

    2009-01-01

    (Lagenorhynchus cruciger) and Hector's dolphins (Cephalorhynchus hectori ) were made in the Drake Passage between Tierra del Fuego and the Antarctic Peninsular and Banks Peninsular Akaroa Harbour, New Zealand with a four element hydrophone array. Analysis of source parameters shows that both species produce...... narrow band high-frequency (NBHF) echolocation clicks. Coastal Hector's dolphins produce clicks with a mean peak frequency of 129 kHz, 3 dB bandwidth of 20 kHz, 57 ys, 10 dB duration, and mean apparent source level (ASL) of 177 dB re 1 yPa (p.-p.). The oceanic hourglass dolphins produce clicks with mean...... peak frequency of 126 kHz, 3 dB bandwidth of 8 kHz, 116 ys, 10 dB duration, and a mean estimated ASL of 197 dB re 1 yPa (p.-p.). Thus, hourglass dolphins apparently produce clicks of higher source level, which should allow them to detect prey at more than twice the distance compared to Hector...

  7. Lamb-dip spectroscopy of the C−N stretching band of methylamine by using frequency-tunable microwave sidebands of CO2 laser lines

    Science.gov (United States)

    Sun, Zhen-Dong; Qi, Shan-Dong; Lees, Ronald M.; Xu, Li-Hong

    2016-01-01

    Lamb-dip spectroscopy of the C−N stretching band of methylamine has been systematically extended to P-, Q-, and R-branch by using microwave sidebands of a large number of CO2 laser lines as frequency-tunable infrared sources in a sub-Doppler spectrometer. Lamb-dip signals of more than 150 spectral lines have been observed with a resolution of 0.4 MHz and their frequencies have been precisely measured with an accuracy of ±0.1 MHz. More than 30 closed combination loops have been formed, which unambiguously confirm the assignments. For over 150 vibrational excited levels in 27 substates, refined term values have been determined and expanded in J(J + 1) power-series to determine the substate origins and the effective rotational constants. For transitions with Aa torsion-inversion symmetry in torsional state υt = 0, 57 K-doublet lines displaying asymmetry splittings have been observed and the splitting constants for levels with K = 1, 2, and 3 in the excited states have been determined. Our results provide accurate experimental information for spectroscopic studies of the interesting vibrational perturbations and intermode interactions related to the C−N stretching mode, directly support astronomical surveys, and are very relevant in practice to identification and frequency determination of the CO2-laser-pumped far-infrared laser lines of methylamine. PMID:27685615

  8. Identification of low frequency anti-erythrocyte antibodies in chronically transfused patient with beta-thalassemia: a case report

    Directory of Open Access Journals (Sweden)

    Ana Rúbia Magalhães Ferreira

    2015-02-01

    Full Text Available The rate of erythrocyte alloimmunization in tranfusion-dependent patients can reach 50%, although the frequency of clinically relevant antibodies in transfused patients is not fully known, it is estimated that about 1% of patients are sensitized to each unit of transfused RBCs. The aim of this study is to report the case of  an 11-year-old girl with ?-thalassemia major, chronically transfused, which was detected in pre-transfusion protocol, the presence of two rare anti-erythrocyte antibodies: anti-Colton b (anti-Cob and anti-Lutheran 14 (anti-Lu14. To survey the clinical and laboratory patient history, research records filed in the archives of the university hospital in which the patient is monitored system was performed. The phenotyping erythrocyte in multitransfused patients is essential to decrease the risk of complications due to alloimmunization and estimate the availability of compatible blood. Thus, the report of this case may contribute to increase knowledge about of the real frequency of uncommon anti-erythrocyte antibodies in thalassemic patients.

  9. Achievement of Preassigned Spectra in the Synthesis of Band-Pass Constant-Envelope Signals by Rapidly Hopping through Discrete Frequencies

    CERN Document Server

    Callegari, Sergio

    2014-01-01

    Spread-spectrum signals are increasingly adopted in fields including communications, testing of electronic systems, Electro-Magnetic Compatibility (EMC) enhancement, ultrasonic non-destructive testing. This paper considers the synthesis of constant-envelope band-pass wave-forms with preassigned spectra via an FM technique using only a limited number of frequencies. In particular, an optimization-based approach for the selection of appropriate modulation parameters and statistical features of the modulating waveform is proposed. By example, it is shown that the design problem generally admits multiple local optima, but can still be managed with relative ease since the local optima can typically be scanned by changing the initial setting of a single parameter.

  10. 某型电台短波频段自动控制通信设计%Communication Design of Automatic Control for a Radio Wave Frequency Band

    Institute of Scientific and Technical Information of China (English)

    孙明亮; 雷坤; 吴彬彬

    2014-01-01

    该文从整体设计的思路到自动控制通信主要内容以及自动控制通信实现的具体流程,阐述了作为新一代短波电台独有的短波频段自动控制通信新技术的设计过程。%This paper to the automatic control of main contents of communication and the specific process of communication to achieve automatic control from the overall design ideas, design is introduced as a new generation of short wave frequency band shortwave radio unique automatic control of new communications technologies.

  11. A single-pole nine-throw antenna switch using radio-frequency microelectromechanical systems technology for broadband multi-mode and multi-band front-ends

    International Nuclear Information System (INIS)

    In this paper, a generic single-pole nine-throw (SP9T) switch is demonstrated using radio-frequency (RF) microelectromechanical systems (MEMS) technology for broadband multi-mode and multi-band front-ends. In order to improve uniformity and yield required for complex switches, 'stress-free' single-crystalline-silicon series dc-contact MEMS switches have been employed instead of metal membrane switches. When tested according to the third-generation partnership project (3GPP) specifications, the antenna switch in this work shows loss, isolation and linearity characteristics better than the conventional semiconductor switches. Measured results showed insertion losses for all nine paths less than 0.5 dB and 2 dB from dc to 2.17 GHz and 21.6 GHz, respectively. Isolations for all input–output and output–output ports are higher than 49 dB at 2.17 GHz. Nonlinearities generated by the MEMS switch were well below the measurement limit of our system setup. The broadband RF performance, together with excellent linearity characteristics, makes this type of MEMS switch a promising candidate for an antenna switch for multi-band and multi-mode front-end applications

  12. Effects of nicotine stimulation on spikes, theta frequency oscillations, and spike-theta oscillation relationship in rat medial septum diagonal band Broca slices

    Institute of Scientific and Technical Information of China (English)

    Dong WEN; Ce PENG; Gao-xiang OU-YANG; Zainab HENDERSON; Xiao-li LI; Cheng-biao LU

    2013-01-01

    Aim:Spiking activities and neuronal network oscillations in the theta frequency range have been found in many cortical areas during information processing.The aim of this study is to determine whether nicotinic acetylcholine receptors (nAChRs) mediate neuronal network activity in rat medial septum diagonal band Broca (MSDB) slices.Methods:Extracellular field potentials were recorded in the slices using an Axoprobe 1A amplifier.Data analysis was performed offline.Spike sorting and local field potential (LFP) analyses were performed using Spike2 software.The role of spiking activity in the generation of LFP oscillations in the slices was determined by analyzing the phase-time relationship between the spikes and LFP oscillations.Circular statistic analysis based on the Rayleigh test was used to determine the significance of phase relationships between the spikes and LFP oscillations.The timing relationship was examined by quantifying the spike-field coherence (SFC).Results:Application of nicotine (250 nmol/L) induced prominent LFP oscillations in the theta frequency band and both small-and large-amplitude population spiking activity in the slices.These spikes were phase-locked to theta oscillations at specific phases.The Rayleigh test showed a statistically significant relationship in phase-locking between the spikes and theta oscillations.Larger changes in the SFC were observed for large-amplitude spikes,indicating an accurate timing relationship between this type of spike and LFP oscillations.The nicotine-induced spiking activity (large-amplitude population spikes) was suppressed by the nAChR antagonist dihydro-β-erythroidine (0.3 μmol/L).Conclusion:The results demonstrate that large-amplitude spikes are phase-locked to theta oscillations and have a high spike-timing accuracy,which are likely a main contributor to the theta oscillations generated in MSDB during nicotine receptor activation.

  13. The first H-band spectrum of the giant planet β Pictoris b [THE FIRST H-BAND SPECTRUM OF THE MASSIVE GAS GIANT PLANET BETA PICTORIS b WITH THE GEMINI PLANET IMAGER

    Energy Technology Data Exchange (ETDEWEB)

    Chilcote, Jeffrey; Barman, Travis; Fitzgerald, Michael P.; Graham, James R.; Larkin, James E.; Macintosh, Bruce; Bauman, Brian; Burrows, Adam S.; Cardwell, Andrew; De Rosa, Robert J.; Dillon, Daren; Doyon, René; Dunn, Jennifer; Erikson, Darren; Gavel, Donald; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Millar-Blanchaer, Max; Morzinski, Katie; Norton, Andrew; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Pueyo, Laurent; Rantakyrö, Fredrik T.; Sadakuni, Naru; Saddlemyer, Leslie; Savransky, Dmitry; Serio, Andrew; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Rémi; Thomas, Sandrine; Wallace, J. Kent; Wiktorowicz, Sloane; Wolff, Schuyler

    2014-12-12

    Using the recently installed Gemini Planet Imager (GPI), we have obtained the first H-band spectrum of the planetary companion to the nearby young star β Pictoris. GPI is designed to image and provide low-resolution spectra of Jupiter-sized, self-luminous planetary companions around young nearby stars. These observations were taken covering the H band (1.65 μm). The spectrum has a resolving power of ~45 and demonstrates the distinctive triangular shape of a cool substellar object with low surface gravity. Using atmospheric models, we find an effective temperature of 1600-1700 K and a surface gravity of log (g) = 3.5-4.5 (cgs units). These values agree well with "hot-start" predictions from planetary evolution models for a gas giant with mass between 10 and 12 MJup and age between 10 and 20 Myr.

  14. A Coherent Study of Emission Lines from Broad-Band Photometry: Specific Star-Formation Rates and [OIII]/H{\\beta} Ratio at 3 < z < 6

    CERN Document Server

    Faisst, A L; Hsieh, B C; Laigle, C; Salvato, M; Tasca, L; Cassata, P; Davidzon, I; Ilbert, O; Fevre, O Le; Masters, D; McCracken, H J; Steinhardt, C; Silverman, J D; De Barros, S; Hasinger, G; Scoville, N Z

    2016-01-01

    We measure the H{\\alpha} and [OIII] emission line properties as well as specific star-formation rates (sSFR) of spectroscopically confirmed 33 cannot be fully explained in a picture of cold accretion driven growth. We find a progressively increasing [OIII]{\\lambda}5007/H{\\beta} ratio out to z~6, consistent with the ratios in local galaxies selected by increasing H{\\alpha} EW (i.e., sSFR). This demonstrates the potential of using "local high-z analogs" to investigate the spectroscopic properties and relations of galaxies in the re-ionization epoch.

  15. Percentage of beta 2 band power of quantitative pharmaco-electroencephalography decreases in propofol anesthetized rabbits A dose-dependent analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND:Quantitative pharmaco-electroencephalography can be used for studying the dose-effect and time-effect relationships of drugs affecting central nervous system.Therefore,it may become an effective means for monitoring the anesthetic degree of anesthetic drug in the operation.OBJECTIVE:To observe the dose-effect relationship of propofol influencing β2-band power of quantitative pharmaco-electroencephalography in rabbits.DESIGN:A randomized block design.SETTING:Department of Anesthesiology,Xuzhou Medical College.MATERIALS:Thirty-six healthy adult rabbits of either gender,weighing (2.4+0.5)kg,of clean grade,were provided by the Laboratory Animal Center of Xuzhou Medical College.The involved rabbits were randomly divided into 3 groups with 12 in each by table of random digit:high-dose propofol group,moderate-dose propofol group,and low-dose propofol group.The protocol was carried out in accordance with animal ethics guidelines for the use and care of animals.METHODS:This study was carried out in the Department of Anesthesiology,Xuzhou Medical College between August 1999 and April 2000.Rabbits in the high-dose propofol group,moderate-dose propofol group,and low-dose propofol group were injected with 10,5 and 2.5 mg/kg propofol (ZENECA Company,British,Batch No.032000),respectively.Before and after intravenous administration of propofol,percentage of β2-band power of quantitative pharmaco-electroencephalography was measured,and the latent and persistent periods when rabbit righting reflex disappeared were observed by quantitative pharmaco-electroencephalography and power spectrum analysis.MAIN OUTCOME MEASURES:① Percentage of β 2-band power of quantitative pharmaco-electroencephalography.②Latent period and persistent period of abolition of righting reflex of rabbits.RESULTS:Thirty-six rabbits were involved in the final analysis.①Effect of propofol on righting reflex of rabbits:Righting reflex disappeared within 1 minute after the rabbits being

  16. Clicking in a killer whale habitat: narrow-band, high-frequency biosonar clicks of harbour porpoise (Phocoena phocoena and Dall's porpoise (Phocoenoides dalli.

    Directory of Open Access Journals (Sweden)

    Line A Kyhn

    Full Text Available Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall's porpoises in British Columbia (BC, Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall's (137±3 kHz and Canadian harbour porpoises (141±2 kHz. Danish harbour porpoise clicks (136±3 kHz were more similar to Dall's porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring.

  17. Antiparasitic antibodies occur with similar frequency in patients with clinically established multiple sclerosis with or without oligoclonal bands in the cerebrospinal fluid

    Directory of Open Access Journals (Sweden)

    Fabiana Cruz Gomes da Fonseca-Papavero

    2013-08-01

    Full Text Available The "hygiene hypothesis" postulates an inverse relationship between the prevalence of parasitic infections and the frequency of multiple sclerosis (MS. Objective: It was to study whether antibodies against parasites could be demonstrated more frequently in blood serum from MS patients with oligoclonal bands (OCB than from MS patients without OCB. Methods: We studied serum samples from 164 patients who had previously been analyzed to investigate OCB. Parasitic antibodies were studied through unidimensional electrophoresis of proteins on polyacrylamide gel against Taenia antigens, searching for antiparasitic specific low molecular weight antibodies and also for antiparasitic nonspecific high molecular weight antibodies. Results: Two of the 103 patients with no evidence of OCB had antibodies of low molecular weight and 59 of them had antibodies of high molecular weight. Of the 61 patients with evidence of OCB, one showed antibodies of low molecular weight and 16 showed antibodies of high molecular weight. Conclusion: Antiparasitic antibodies are detected with similar frequency in MS patients with OCB and in MS patients without OCB.

  18. Frequency and Characteristics of Infections Caused by Extended-Spectrum Beta-Lactamase-Producing Organisms in Neonates: A Prospective Cohort Study

    Directory of Open Access Journals (Sweden)

    Nandini Vijayakanthi

    2013-01-01

    Full Text Available This prospective cohort study was conducted to determine the frequency of infections caused by extended-spectrum beta-lactamase- (ESBL- producing organisms, various bacteria producing ESBL, antibiotic susceptibility of these organisms, and the risk factors associated with these infections in a neonatal intensive care unit in a tertiary care hospital in North India. Of the 150 neonates enrolled in the study, 47 culture-positive neonates were included in the study cohort and were divided into two groups: ESBL-positive (8 neonates and ESBL-negative (39 neonates cohorts. Various organisms were isolated from 72 culture samples in these 47 neonates. Of these, 10 culture samples grew ESBL-positive organisms and 62 samples grew ESBL-negative organisms. The frequency of ESBL-producing organisms was found to be 5.3%. ESBL infection incidence densities were found to be 3.4 per 1000 patient-days. Klebsiella (60% was the most common organism producing ESBL followed by Escherichia coli (30% and Pseudomonas (10%. Eighty percent of the ESBL-producing organisms were sensitive to piperacillin-tazobactam. Risk factors found significant by univariate analysis (P7 days, length of hospitalization, length of level 3 stay, prior antibiotic use, central venous catheter duration, peripherally inserted central venous catheter duration, and total parenteral nutrition duration. Factors that retained significance in the logistic regression model were duration of hospital stay (adjusted OR: 0.958, CI: 0.920–0.997, and P value = 0.037 and gestational age (adjusted OR: 1.39, CI: 1.037–1.865, and P value = 0.028. There was no significant difference in the mortality between the two groups.

  19. Hydrogenation of the alpha,beta-Unsaturated Aldehydes Acrolein, Crotonaldehyde, and Prenal over Pt Single Crystals: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Kliewer, C.J.; Somorjai, G.A.

    2008-11-26

    Sum-frequency generation vibrational spectroscopy (SFG-VS) and kinetic measurements using gas chromatography have been used to study the surface reaction intermediates during the hydrogenation of three {alpha},{beta}-unsaturated aldehydes, acrolein, crotonaldehyde, and prenal, over Pt(111) at Torr pressures (1 Torr aldehyde, 100 Torr hydrogen) in the temperature range of 295K to 415K. SFG-VS data showed that acrolein has mixed adsorption species of {eta}{sub 2}-di-{sigma}(CC)-trans, {eta}{sub 2}-di-{sigma}(CC)-cis as well as highly coordinated {eta}{sub 3} or {eta}{sub 4} species. Crotonaldehyde adsorbed to Pt(111) as {eta}{sub 2} surface intermediates. SFG-VS during prenal hydrogenation also suggested the presence of the {eta}{sub 2} adsorption species, and became more highly coordinated as the temperature was raised to 415K, in agreement with its enhanced C=O hydrogenation. The effect of catalyst surface structure was clarified by carrying out the hydrogenation of crotonaldehyde over both Pt(111) and Pt(100) single crystals while acquiring the SFG-VS spectra in situ. Both the kinetics and SFG-VS showed little structure sensitivity. Pt(100) generated more decarbonylation 'cracking' product while Pt(111) had a higher selectivity for the formation of the desired unsaturated alcohol, crotylalcohol.

  20. Excitation spectra and ground-state properties from density functional theory for the inverted band-structure systems $\\beta$-HgS, HgSe, and HgTe

    CERN Document Server

    Delin, A

    2002-01-01

    We have performed a systematic density-functional study of the mercury chalcogenide compounds $\\beta$-HgS, HgSe, and HgTe using an all-electron full-potential linear muffin-tin orbital (FP-LMTO) method. We find that, in the zinc-blende structure, both HgSe and HgTe are semimetals whereas $\\beta$-HgS has a small spin-orbit induced band gap. Our calculated relativistic photoemission and inverse photoemission spectra (PES and IPES, respectively) reproduce very well the most recently measured spectra, as do also our theoretical optical spectra. In contrast to the normal situation, we find that the local density approximation (LDA) to the density functional gives calculated equilibrium volumes in much better agreement with experiment than does the generalized gradient corrected functional (GGA). We also address the problem of treating relativistic $p$ electrons with methods based on a scalar-relativistic basis set, and show that the effect is rather small for the present systems.

  1. Beta band transcranial alternating (tACS and direct current stimulation (tDCS applied after initial learning facilitate retrieval of a motor sequence

    Directory of Open Access Journals (Sweden)

    Vanessa eKrause

    2016-01-01

    Full Text Available The primary motor cortex (M1 contributes to the acquisition and early consolidation of a motor sequence. Although the relevance of M1 excitability for motor learning has been supported, the significance of M1 oscillations remains an open issue. This study aims at investigating to what extent retrieval of a newly learned motor sequence can be differentially affected by motor-cortical transcranial alternating (tACS and direct current stimulation (tDCS. Alpha (10 Hz, beta (20 Hz or sham tACS was applied in 36 right-handers. Anodal or cathodal tDCS was applied in 30 right-handers. Participants learned an eight-digit serial reaction time task (SRTT; sequential vs. random with the right hand. Stimulation was applied to the left M1 after SRTT acquisition at rest for ten minutes. Reaction times were analyzed at baseline, end of acquisition, retrieval immediately after stimulation and reacquisition after eight further sequence repetitions.Reaction times during retrieval were significantly faster following 20 Hz tACS as compared to 10 Hz and sham tACS indicating a facilitation of early consolidation. TDCS yielded faster reaction times, too, independent of polarity. No significant differences between 20 Hz tACS and tDCS effects on retrieval were found suggesting that 20 Hz effects might be associated with altered motor-cortical excitability. Based on the behavioural modulation yielded by tACS and tDCS one might speculate that altered motor-cortical beta oscillations support early motor consolidation possibly associated with neuroplastic reorganization.

  2. Frequency of alpha- and beta-haemolysin in Staphylococcus aureus of bovine and human origin - A comparison between pheno- and genotype and variation in phenotypic expression

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Larsen, H.D.; Eriksen, N.H.R.;

    1999-01-01

    isolates and 24% of the septicaemia isolates did so. No change in expression of haemolysins could be observed after subcultivation of bovine isolates in human blood and milk. After 5 to 10 subcultures in bovine blood and 1 to 4 in bovine milk, 9 of 10 human isolates originally phenotypically beta......-haemolysin negative initiated the expression of beta-haemolysin. This study showed that a larger proportion of S. aureus of bovine origin carry the beta-haemolysin gene compared to isolates from humans. Furthermore, a larger number of the isolates of bovine origin carrying the beta-haemolysin gene express this gene...... phenotypically compared to isolates of human origin....

  3. Microwave absorption in X and Ku band frequency of cotton fabric coated with Ni–Zn ferrite and carbon formulation in polyurethane matrix

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, K.K., E-mail: krishna62@rediffmail.com [Defence Materials and Stores Research and Development Establishment, Kanpur PO, GT Road, Kanpur 208013 (India); Abbas, S.M.; Goswami, T.H. [Defence Materials and Stores Research and Development Establishment, Kanpur PO, GT Road, Kanpur 208013 (India); Abhyankar, A.C. [Defence Institute of Advanced Technology( DIAT), Giri Nagar, Pune 411025 (India)

    2014-08-01

    The present study highlights various microwave properties, i.e. reflection, transmission, absorption and reflection loss, of the coated cotton fabric [formulation: Ni–Zn ferrite (Ni {sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) and carbon black (acetylene black) at concentrations of 30, 40, 50, 60 and70 g of ferrite and 5 g carbon in each 100 ml polyurethane] evaluated at 8–18 GHz frequency. The uniform density of filling materials in coated fabrics (dotted marks in SEM micrograph) indicates homogeneous dispersion of conducting fillers in polyurethane and the density of filling material cluster increases with increase in ferrite concentration. SEM images also show uniform coating of conducting fillers/resin system over individual fibers and interweave spaces. The important parameters governing the microwave properties of coated fabrics i.e. permittivity and permeability, S-parameters, reflection loss, etc. were studied in a HVS free space microwave measurement system. The lossy character of coated fabric is found to increase with increase of ferrite content; the ferrite content decreases the impedance and increases the permittivity and permeability values. The 1.6–1.8 mm thick coated fabric sample (40 wt% ferrite, 3 wt% carbon and 57 wt% PU) has shown about 40% absorption, 20% transmission and 40% reflectance in X (8.2–12.4 GHz) and Ku (12–18 GHz) frequency bands. The reflection loss at 13.5 GHz has shown the highest peak value (22.5 dB) due to coated sample optical thickness equal to λ/4 and more than 7.5 dB in entire Ku band. Owing to its thin and flexible nature, the coated fabric can be used as apparel in protecting human being from hazardous microwaves and also as radar camouflage covering screen in defense. - Highlights: • Ni–Zn ferrite (Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) with acetylene black found effective coating for microwave absorption. • Coating formulation containing 40 wt% ferrite, 3 wt% carbon and 57 wt% PU offered 40% absorption, 20

  4. Theoretical and Numerical Approaches for Determining the Reflection and Transmission Coefficients of OPEFB-PCL Composites at X-Band Frequencies.

    Science.gov (United States)

    Ahmad, Ahmad F; Abbas, Zulkifly; Obaiys, Suzan J; Ibrahim, Norazowa; Hashim, Mansor; Khaleel, Haider

    2015-01-01

    Bio-composites of oil palm empty fruit bunch (OPEFB) fibres and polycaprolactones (PCL) with a thickness of 1 mm were prepared and characterized. The composites produced from these materials are low in density, inexpensive, environmentally friendly, and possess good dielectric characteristics. The magnitudes of the reflection and transmission coefficients of OPEFB fibre-reinforced PCL composites with different percentages of filler were measured using a rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in the X-band frequency range. In contrast to the effective medium theory, which states that polymer-based composites with a high dielectric constant can be obtained by doping a filler with a high dielectric constant into a host material with a low dielectric constant, this paper demonstrates that the use of a low filler percentage (12.2%OPEFB) and a high matrix percentage (87.8%PCL) provides excellent results for the dielectric constant and loss factor, whereas 63.8% filler material with 36.2% host material results in lower values for both the dielectric constant and loss factor. The open-ended probe technique (OEC), connected with the Agilent vector network analyzer (VNA), is used to determine the dielectric properties of the materials under investigation. The comparative approach indicates that the mean relative error of FEM is smaller than that of NRW in terms of the corresponding S21 magnitude. The present calculation of the matrix/filler percentages endorses the exact amounts of substrate utilized in various physics applications. PMID:26474301

  5. Multi-frequency (S, X, Q and W-band) EPR and ENDOR Study of Vanadium(IV) Incorporation in the Aluminium Metal-Organic Framework MIL-53.

    Science.gov (United States)

    Nevjestić, Irena; Depauw, Hannes; Leus, Karen; Kalendra, Vidmantas; Caretti, Ignacio; Jeschke, Gunnar; Van Doorslaer, Sabine; Callens, Freddy; Van Der Voort, Pascal; Vrielinck, Henk

    2015-10-01

    Doping the well-known metal-organic framework MIL-53(Al) with vanadium(IV) ions leads to significant changes in the breathing behaviour and might have repercussions on the catalytic behaviour as well. To understand the properties of such a doped framework, it is necessary to determine where dopant ions are actually incorporated. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are applied to reveal the nearest environment of the paramagnetic vanadium(IV) dopant ions. EPR spectra of as-synthesised vanadium-doped MIL-53 are recorded at S-, X-, Q- and W-band microwave frequencies. The EPR spectra suggest that at low dopant concentrations (1.0-2.6 mol %) the vanadium(IV) ions are well dispersed in the matrix. Varying the vanadium dopant concentration within this range or the dopant salt leads to the same dominant EPR component. In the ENDOR spectra, hyperfine (HF) interactions with (1) H, (27) Al and (51) V nuclei are observed. The HF parameters extracted from simulations strongly suggest that the vanadium(IV) ions substitute Al in the framework. PMID:26305910

  6. Compact MIMO Microstrip Antennas for USB Dongle Operating in 2.5–2.7 GHz Frequency Band

    Directory of Open Access Journals (Sweden)

    Vladimir Ssorin

    2012-01-01

    Full Text Available This paper considers design of microstrip MIMO antennas for an LTE/WiMAX USB dongle operating in the 2.5–2.7 GHz frequency band. The MIMO system includes two antenna elements with an additional requirement of high isolation between them that is especially difficult to realize due to size limitations of a USB dongle. Three approaches to achieve the needed system characteristics using microstrip PCB antennas are proposed. For the first design, high port-to-port isolation is achieved by using a decoupling techniques based on a direct connection of the antenna elements. For the second approach, high port-to-port isolation of the MIMO antenna system is realized by a lumped decorrelation capacitance between antenna elements feeding points. The third proposed antenna system does not use any special techniques, and high port-to-port isolation is achieved by using only the properties of a developed printed inverted-F antenna element. The designed MIMO antenna systems have the return loss S11 and the insertion loss S21 bandwidths of more than 200 MHz at the −8 dB level with the correlation coefficient lower than 0.1 and exhibit pattern diversity when different antenna elements are excited. Experimental measurements of the fabricated antenna systems proved the characteristics obtained from electromagnetic simulation.

  7. Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector

    CERN Document Server

    Hernandez-Garcia, C; Asova, G; Bakr, M; Boonpornprasert, P; Good, J; Gross, M; Huck, H; Isaev, I; Kalantaryan, D; Khojoyan, M; Kourkafas, G; Lishilin, O; Malyutin, D; Melkumyan, D; Oppelt, A; Otevrel, M; Pathak, G; Renier, Y; Rublack, T; Stephan, F; Vashchenko, G; Zhao, Q

    2016-01-01

    This paper discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency cavity (RF gun) from Cs2Te photocathodes illuminated with ps-long UV laser pulses when the laser transverse distribution consists of a flat-top core with Gaussian-like decaying halo. The produced charge shows a linear dependence at low laser pulse energies as expected in the quantum efficiency limited emission regime, while its dependence on laser pulse energy is observed to be much weaker for higher values, due to space charge limited emission. However, direct plug-in of experimental parameters into the space charge tracking code ASTRA yields lower output charge in the space charge limited regime compared to measured values. The rate of increase of the produced charge at high laser pulse energies close to the space charge limited emission regime seems to be proportional to the amount of halo present in the radial laser profile since the charge from the core has saturated already. By utilizing co...

  8. Effects of beta-amyloid protein on M1 and M2 subtypes of muscarinic acetylcholine receptors in the medial septum-diagonal band complex of the rat: relationship with cholinergic, GABAergic, and calcium-binding protein perikarya.

    Science.gov (United States)

    González, Iván; Arévalo-Serrano, Juan; Sanz-Anquela, José Miguel; Gonzalo-Ruiz, Alicia

    2007-06-01

    Cortical cholinergic dysfunction has been correlated with the expression and processing of beta-amyloid precursor protein. However, it remains unclear as to how cholinergic dysfunction and beta-amyloid (Abeta) formation and deposition might be related to one another. Since the M1- and M2 subtypes of muscarinic acetylcholine receptors (mAChRs) are considered key molecules that transduce the cholinergic message, the purpose of the present study was to assess the effects of the injected Abeta peptide on the number of M1mAchR- and M2mAChR-immunoreactive cells in the medial septum-diagonal band (MS-nDBB) complex of the rat. Injections of Abeta protein into the retrosplenial cortex resulted in a decrease in M1mAChR and M2mAChR immunoreactivity in the MS-nDBB complex. Quantitative analysis revealed a significant reduction in the number of M1mAChR- and M2mAChR-immunoreactive cells in the medial septum nucleus (MS) and in the horizontal nucleus of the diagonal band of Broca (HDB) as compared to the corresponding hemisphere in control animals and with that seen in the contralateral hemisphere, which corresponds to the PBS-injected side. Co-localization studies showed that the M1mAChR protein is localized in GABA-immunoreactive cells of the MS-nDBB complex, in particular those of the MS nucleus, while M2mAChR protein is localized in both the cholinergic and GABAergic cells. Moreover, GABAergic cells containing M2mAChR are mainly localized in the MS nucleus, while cholinergic cells containing M2mAChR are localized in the MS and the HDB nuclei. Our findings suggest that Abeta induces a reduction in M1mAChR- and M2mAChR-containing cells, which may contribute to impairments of cholinergic and GABAergic transmission in the MS-nDBB complex.

  9. Technology of electronic mail in the maritime high frequency band%海上高频电子邮件技术

    Institute of Scientific and Technical Information of China (English)

    王化民; 冯文仙; 常满文

    2012-01-01

    The technology of electronic mail in the maritime high frequency band is the important part of the technology of maritime HF digit traffic. It uses PACTOR-Ⅲ protocol and maritime MF/HF radioes in existence to carry out traffic with land user via global link network ( GLN) . The technology of maritime HF digit traffic mostly includes P ACTOR-Ⅲ protocol and T-BUS protocol. It has very important value to introduce into maritime HF data traffic technology that the bandwidth and speed levels, modulation, coding and data rates, crest factor and transmitter output power, structure of packets and control signals, signal characteristics,T-BUS protocol and so on technique matter of maritime digit traffic areanalyzed.%海上高频电子邮件技术[1]是海上高频数字通信技术的重要部分,使用PACTOR-Ⅲ协议和现有海上中/高频无线电设备,经由全球链路网( GLN)与陆上用户进行通信.海上高频数字通信技术主要包括PACTOR-Ⅲ协议和T总线协议.对海上高频数字通信的带宽和传输速率、调制、编码和码率、振幅因数与发射机输出功率、数据包的结构、控制信号、信号特征等技术问题的分析,对海上高频段新通信技术的引进有非常重要的价值.

  10. Theoretical and Numerical Approaches for Determining the Reflection and Transmission Coefficients of OPEFB-PCL Composites at X-Band Frequencies.

    Directory of Open Access Journals (Sweden)

    Ahmad F Ahmad

    Full Text Available Bio-composites of oil palm empty fruit bunch (OPEFB fibres and polycaprolactones (PCL with a thickness of 1 mm were prepared and characterized. The composites produced from these materials are low in density, inexpensive, environmentally friendly, and possess good dielectric characteristics. The magnitudes of the reflection and transmission coefficients of OPEFB fibre-reinforced PCL composites with different percentages of filler were measured using a rectangular waveguide in conjunction with a microwave vector network analyzer (VNA in the X-band frequency range. In contrast to the effective medium theory, which states that polymer-based composites with a high dielectric constant can be obtained by doping a filler with a high dielectric constant into a host material with a low dielectric constant, this paper demonstrates that the use of a low filler percentage (12.2%OPEFB and a high matrix percentage (87.8%PCL provides excellent results for the dielectric constant and loss factor, whereas 63.8% filler material with 36.2% host material results in lower values for both the dielectric constant and loss factor. The open-ended probe technique (OEC, connected with the Agilent vector network analyzer (VNA, is used to determine the dielectric properties of the materials under investigation. The comparative approach indicates that the mean relative error of FEM is smaller than that of NRW in terms of the corresponding S21 magnitude. The present calculation of the matrix/filler percentages endorses the exact amounts of substrate utilized in various physics applications.

  11. Inter-trial analysis of post-movement Beta activities in EEG signals using multivariate empirical mode decomposition.

    Science.gov (United States)

    Chang, Hsiang-Chih; Lee, Po-Lei; Lo, Men-Tzung; Wu, Yu-Te; Wang, Kuo-Wei; Lan, Gong-Yau

    2013-07-01

    Event-related desynchronization/synchronization (ERD/ERS) is a technique to quantify subject's nonphase-locked neural activities underlying specific frequency bands, reactive to external/internal stimulus. However, conventional ERD/ERS studies usually utilize fixed frequency band determined from one or few channels to filter whole-head EEG/MEG data, which may inevitably include task-unrelated signals and result in underestimation of reactive oscillatory activities in multichannel studies. In this study, we adopted multivariate empirical mode decomposition (MEMD) to extract beta-related oscillatory activities in performing self-paced right and left index-finger lifting tasks. The MEMD extracts common modes from all channels in same-index intrinsic mode functions (IMFs) which allows the temporal-frequency features among different channels can be compared in each subband. The beta-band oscillatory activities were further bandpass filtered within trial-specific beta bands determined from sensorimotor-related channels (C3 and C4), and then rectified using amplitude modulation method to detect trial-by-trial beta rebound (BR) values in ERS time courses. The validity of the MEMD approach in BR values extraction has been demonstrated in multichannel EEG study which showed larger BR values than conventional ERS technique. The MEMD-based method enables the trial-by-trial extraction of sensorimotor oscillatory activities which might allow the exploration of subtle brain dynamics in future studies. PMID:23661320

  12. DUAL BAND MONOPOLE ANTENNA DESIGN

    Directory of Open Access Journals (Sweden)

    P. Jithu

    2013-06-01

    Full Text Available The WLAN and Bluetooth applications become popular in mobile devices, integrating GSM and ISM bands operation in one compact antenna, can reduce the size of mobile devices. Recently, lot many investigations are carried out in designing a dual band antennas with operating frequencies in GSM band and in ISM band for mobile devices. Printed monopoles are under this investigation. In this paper, dual-band printed monopoles are presented to operate at GSM band i.e. 900 MHz and ISM band i.e. 2.4 GHz. We intend to observe the antenna characteristics on the network analyzer and verify the theoretical results with the practical ones.

  13. Change of deformation at the backbending in the yrast superdeformed band of {sup 144}Gd

    Energy Technology Data Exchange (ETDEWEB)

    Ur, C.A.; Bolzonella, G.P.; Bazzacco, D. [dell`Universita, Padova (Italy)]|[INFN, Padova (Italy)] [and others

    1996-12-31

    A mean lifetime measurement using the Doppler shift attenuation method has been performed at GASP in order to extract the quadrupole moment of the yrast SD band of {sup 144}Gd. The extracted intrinsic quadrupole moments, being Q{sub 0}=13.7 eb above the backbending and Q{sub 0}=11.8 eb below the backbending, are consistent with a change of deformation from {beta}{sub 2}=0.51 (at {beta}{sub 4} {approx} 0.050) to {beta}{sub 2}=0.45 (at {beta}{sub 4} {approx}0.035). The experimental results are in nice agreement with the theoretical predictions, which revealed that the second well in {sup 144}Gd arises essentially from the very favored shell structure at N=80 and Z=64. The occupation at higher frequency of the aligned N=6 proton orbitals drives the nucleus to a slightly more deformed shape.

  14. Design of triple bandpass frequency selective surface in terahertz wave band for radio astronomy%射电天文用太赫兹三通带频率选择表面设计∗

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    A single screen terahertz frequency selective surface (FS) using the improved split ring resonators (SRRs) is designed in this paper. The resonance unit of an improved SRR consists of an open seam metal patch, while the physical size of the open seam metal patch will directly affect the stepped impedance characteristics. In the paper, LC equivalent circuit model for the improved SRR unit structure is established to extract the equivalent circuit model parameters. Then the relationship between the fundamental frequency of the FSS formula and the harmonics is obtained from the basic theory of the transmission line. Compared to the traditional uniform SRR, the control of multi-band in the improved SRR is more flexible. It is an outstanding characteristic for multi-band FSS design. Based on this characteristic, the triple-band terahertz FSS centered at 0.46, 0.86 and 1.03 THz respectively is designed successively, which can be used in radio astronomy application. By using HFSS 13.0 electromagnetic software simulation, many important indicators such as the key parameters that affect the transmission characteristics of the FSS, periodic intervals, miniaturization degree and the sensitivity of the incidence angle have been studied and analyzed. Both the theoretical analysis and simulated results demonstrate the validity of the method. The triple-band FSS using the improved SRR has a lot of reformative performances. It is shown that the reflection coefficients of triple-band FSS using the improved SRR are −37.6 dB,−13 dB, and −19.6 dB, respectively. On the other hand, it owns the stable frequency response characteristics in the 0◦—60◦ range, which is beneficial to a large incidence angle. In addition, a high degree of miniaturization and the low loss characteristics are the another two significant advantages of this FSS. This triple-band FSS with improved SRR has potential applications in the terahertz frequency radio astronomy polarizer, beam splitter, mirror

  15. FREQUENCY OPTIMIZATION APPROACH FOR DESIGNING M-BAND BIORTHOGONAL SYMMETRIC WAVELETS%M进制双正交对称小波的频率优化设计

    Institute of Scientific and Technical Information of China (English)

    王建卫; 张泽银; 黄达人

    2003-01-01

    In this paper, a new method is presented for designing M-band biorthogonalsymmetric waveletsThe design problem of biorthogonal linear-phase scaling filters and waveletfilters as a quadratic programming problem with the linear constraints is formulatedTheclosed-form solution is given and a design example is presented.

  16. The Band Pass Filter

    OpenAIRE

    Christiano, Lawrence J.; Terry J. Fitzgerald

    1999-01-01

    The `ideal' band pass filter can be used to isolate the component of a time series that lies within a particular band of frequencies. However, applying this filter requires a dataset of infinite length. In practice, some sort of approximation is needed. Using projections, we derive approximations that are optimal when the time series representations underlying the raw data have a unit root, or are stationary about a trend. We identify one approximation which, though it is only optimal for one...

  17. Semantics in the motor system: motor-cortical beta oscillations reflect semantic knowledge of end-postures for object use

    Directory of Open Access Journals (Sweden)

    Michiel Van Elk

    2010-02-01

    Full Text Available In the present EEG study we investigated whether semantic knowledge for object use is represented in motor-related brain areas. Subjects were required to perform actions with everyday objects and to maintain either a meaningful or a meaningless end posture with the object. Analysis of the EEG data focused on the beta-frequency band, as previous studies have indicated that the maintenance of a posture is reflected in stronger beta-oscillations. Time frequency analysis indicated that the execution of actions resulting in a meaningless compared to a meaningful end posture was accompanied by a stronger beta-desynchronization towards the end of the movement and a stronger subsequent beta-rebound after posture-onset. The effect in the beta-frequency band was localized to premotor, parietal and medial frontal areas and could not be attributed to differences in timing or movement complexity between meaningful and meaningless actions. Together these findings directly show that the motor system is differentially activated during the execution and maintenance of semantically correct or incorrect end postures. This suggests that semantic object knowledge is indeed represented in motor-related brain areas, organized around specific end postures associated with the use of objects.

  18. The Gamma Frequency Band Neural Oscillation:Generation Mechanisms and Functions%Gamma神经振荡产生机制及其功能研究进展

    Institute of Scientific and Technical Information of China (English)

    王静; 李小俚; 邢国刚; 万有

    2011-01-01

    Gamna神经振荡的频率在30~100Hz之间,存在于动物和人类大脑的多个区域,如丘脑、体感皮层以及海马等部位,在各个尺度水平上都可被检测到.抑制性中间神经元组成的神经网络是产生此高频节律性活动的主要条件之一.皮层的gamma神经振荡与丘脑-皮层系统有关.Gamma神经振荡具有易化突触可塑性和调节神经网络的作用,主要参与感觉特征绑定、选择性注意以及记忆等高级功能.%Gamma band oscillation ranges from 30 to 100 Hz. It can be recorded in many brain areas such as somotosensory cortex, hippocampus and thalamus. The gamma band oscillation can be detected at different levels such as microscopic (spikes), mesoscopic (local field potentials, LFP) and macroscopic (electroencephalogram, EEG) level. GABAergic inhibitory interneuron network is considered as the main source of the gamma oscillation generation, and the cortical gamma oscillation is also related with the interaction of thalamo-cortical system. Gamma band oscillation is associated with sensory and cognition functions, in particular the feature binding, selective attention and memory processing.

  19. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier

    2013-01-01

    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

  20. Frequency Of Pancreatic Beta-Cell Autoimmunity Markers In Patients With Autoimmune Thyroid Disease Frecuencia de marcadores de autoinmunidad beta pancreática en pacientes con enfermedad tiroidea autoinmune

    Directory of Open Access Journals (Sweden)

    María E. Primo

    2008-02-01

    Full Text Available A total of 305 ambulatory patients recruited at the Division of Endocrinology, Hospital de Clínicas, University of Buenos Aires, with autoimmune thyroid disease (AITD were studied to search for associations between autoimmune thyroid disease and presence of serum markers of autoimmune diabetes mellitus. Screening for markers of pancreatic beta-cell autoimmunity was performed by radioligand binding assays (RBA as follows: autoantibodies to glutamic acid decarboxylase (GADA and proinsulin (PAA were determined in all sera, whereas autoantibodies to protein tyrosine phosphatase (IA-2A and insulin (IAA were additionally measured in 200 sera randomly selected from the total collection. In addition, every GADA positive serum among the remaining 105 sera was systematically tested for the presence of IA-2A and IAA. In the cohort of 305 AITD patients 22 (7.2% were previously diagnosed as type 1, type 2 or insulin-requiring type 2 diabetics. Ten of these patients presented serum marker positivity specific for β-cell autoantigens and 12 were marker negative. On the other hand, considering the majority of non-diabetic AITD patients (n=283, β-cell marker positivity was detected in 17 individuals (6.0%. The prevalence of autoimmune diabetes markers was much higher in the studied population than in the general population utilized as a control group, and GADA was the most frequent marker.Se investigó la asociación entre enfermedad tiroidea autoinmune y la presencia de marcadores séricos de diabetes mellitus en 305 pacientes ambulatorios con enfermedad tiroidea autoinmune reclutados en la División Endocrinología. La búsqueda de marcadores de autoinmunidad contra las células beta pancreáticas se realizó por la técnica de unión de radioligandos (RBA como se detalla a continuación: se determinaron autoanticuerpos contra la decarboxilasa del ácido glutámico (GADA y proinsulina (PAA en todos los sueros, mientras que los anticuerpos contra la prote

  1. Cross-frequency coupling of brain oscillations in studying motivation and emotion.

    Science.gov (United States)

    Schutter, Dennis J L G; Knyazev, Gennady G

    2012-03-01

    Research has shown that brain functions are realized by simultaneous oscillations in various frequency bands. In addition to examining oscillations in pre-specified bands, interactions and relations between the different frequency bandwidths is another important aspect that needs to be considered in unraveling the workings of the human brain and its functions. In this review we provide evidence that studying interdependencies between brain oscillations may be a valuable approach to study the electrophysiological processes associated with motivation and emotional states. Studies will be presented showing that amplitude-amplitude coupling between delta-alpha and delta-beta oscillations varies as a function of state anxiety and approach-avoidance-related motivation, and that changes in the association between delta-beta oscillations can be observed following successful psychotherapy. Together these studies suggest that cross-frequency coupling of brain oscillations may contribute to expanding our understanding of the neural processes underlying motivation and emotion. PMID:22448078

  2. Enhanced Microwave Absorption of SiO2-Coated Fe0.65Co0.35 Flakes at a Wide Frequency Band (1-18 GHz)

    Science.gov (United States)

    Luo, Hui; Gong, Rongzhou; Wang, Xian; Song, Kai; Chen, Yajie; Harris, Vincent G.

    2016-07-01

    Fe0.65Co0.35 (Fe-35Co) flakes were coated with SiO2 by the Stober process. The complex permittivity and permeability of both Fe-35Co and Fe-35Co/SiO2 composites were investigated over the frequency range of 1-18 GHz. Two dielectric resonance peaks were found in the Fe-35Co/SiO2 composite. Magnetic loss was verified to arise predominately from the natural resonance. Of particular importance is the natural resonance frequency increases with the SiO2 cladding. The experiments indicated that a reflection loss (RL) less than -20 dB for the Fe-35Co/SiO2 composites can be measured over the frequency range of 5.16-10.6 GHz with an absorbing thickness of 2-3.5 mm. Furthermore, an optimal RL of -60.23 dB was observed at 6.27 GHz with a thickness of 2.93 mm. The results provide a valuable path towards realizing microwave absorption over a wide frequency range.

  3. Simultaneous apatial and frequency domain filtering at the antenna inputs achieving up to +10dBm out-of-band/beam P 1dB

    NARCIS (Netherlands)

    Ghaffari, A.; Klumperink, E.A.M.; Vliet, van F.E.; Nauta, B.

    2013-01-01

    Multi-antenna transceivers with beam-forming are recently gaining interest for low GHz frequencies (<6GHz) [1-4]. In the antenna beam, (phase-shifted) signals from multiple antennas add constructively, improving SNR, while out-ofbeam signals add destructively (i.e. spatial filtering). Usually the su

  4. Single Brillouin frequency shifted S-band multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier in ring cavity

    Science.gov (United States)

    Reshak, A. H.; Hambali, N. A. M. Ahmad; Shahimin, M. M.; Wahid, M. H. A.; Anwar, Nur Elina; Alahmed, Zeyad A.; Chyský, J.

    2016-10-01

    This paper is focusing on simulation and analyzing of S-band multi-wavelength Brillouin-Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity. Raman amplifier-average power model is employed for signal amplification. This laser system is operates in S-band wavelength region due to vast demanding on transmitting the information. Multi-wavelength fiber lasers based on hybrid Brillouin-Raman gain configuration supported by Raman scattering effect have attracted significant research interest due to its ability to produced multi-wavelength signals from a single light source. In multi-wavelength Brillouin-Raman fiber, single mode fiber is utilized as the nonlinear gain medium. From output results, 90% output coupling ratio has ability to provide the maximum average output power of 43 dBm at Brillouin pump power of 20 dBm and Raman pump power of 14 dBm. Furthermore, multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier is capable of generated 7 Brillouin Stokes signals at 1480 nm, 1510 nm and 1530 nm.

  5. Measurement of DNA damage after exposure to electromagnetic radiation in the cellular phone communication frequency band (835.62 and 847.74 MHz).

    Science.gov (United States)

    Malyapa, R S; Ahern, E W; Straube, W L; Moros, E G; Pickard, W F; Roti Roti, J L

    1997-12-01

    Mouse C3H 10T1/2 fibroblasts and human glioblastoma U87MG cells were exposed to cellular phone communication frequency radiations to investigate whether such exposure produces DNA damage in in vitro cultures. Two types of frequency modulations were studied: frequency-modulated continuous-wave (FMCW), with a carrier frequency of 835.62 MHz, and code-division multiple-access (CDMA) centered on 847.74 MHz. Exponentially growing (U87MG and C3H 10T1/2 cells) and plateau-phase (C3H 10T1/2 cells) cultures were exposed to either FMCW or CDMA radiation for varying periods up to 24 h in specially designed radial transmission lines (RTLs) that provided relatively uniform exposure with a specific absorption rate (SAR) of 0.6 W/kg. Temperatures in the RTLs were monitored continuously and maintained at 37 +/- 0.3 degrees C. Sham exposure of cultures in an RTL (negative control) and 137Cs gamma-irradiated samples (positive control) were included with every experiment. The alkaline comet assay as described by Olive et al. (Exp. Cell Res. 198, 259-269, 1992) was used to measure DNA damage. No significant differences were observed between the test group exposed to FMCW or CDMA radiation and the sham-treated negative controls. Our results indicate that exposure of cultured mammalian cells to cellular phone communication frequencies under these conditions at an SAR of 0.6 W/kg does not cause DNA damage as measured by the alkaline comet assay. PMID:9399708

  6. EEG Bands of Wakeful Rest, Slow-Wave and Rapid-Eye-Movement Sleep at Different Brain Areas in Rats.

    Science.gov (United States)

    Jing, Wei; Wang, Yanran; Fang, Guangzhan; Chen, Mingming; Xue, Miaomiao; Guo, Daqing; Yao, Dezhong; Xia, Yang

    2016-01-01

    Accumulating evidence reveals that neuronal oscillations with various frequency bands in the brain have different physiological functions. However, the frequency band divisions in rats were typically based on empirical spectral distribution from limited channels information. In the present study, functionally relevant frequency bands across vigilance states and brain regions were identified using factor analysis based on 9 channels EEG signals recorded from multiple brain areas in rats. We found that frequency band divisions varied both across vigilance states and brain regions. In particular, theta oscillations during REM sleep were subdivided into two bands, 5-7 and 8-11 Hz corresponding to the tonic and phasic stages, respectively. The spindle activities of SWS were different along the anterior-posterior axis, lower oscillations (~16 Hz) in frontal regions and higher in parietal (~21 Hz). The delta and theta activities co-varied in the visual and auditory cortex during wakeful rest. In addition, power spectra of beta oscillations were significantly decreased in association cortex during REM sleep compared with wakeful rest. These results provide us some new insights into understand the brain oscillations across vigilance states, and also indicate that the spatial factor should not be ignored when considering the frequency band divisions in rats. PMID:27536231

  7. EEG Bands of Wakeful Rest, Slow-Wave and Rapid-Eye-Movement Sleep at Different Brain Areas in Rats

    Science.gov (United States)

    Jing, Wei; Wang, Yanran; Fang, Guangzhan; Chen, Mingming; Xue, Miaomiao; Guo, Daqing; Yao, Dezhong; Xia, Yang

    2016-01-01

    Accumulating evidence reveals that neuronal oscillations with various frequency bands in the brain have different physiological functions. However, the frequency band divisions in rats were typically based on empirical spectral distribution from limited channels information. In the present study, functionally relevant frequency bands across vigilance states and brain regions were identified using factor analysis based on 9 channels EEG signals recorded from multiple brain areas in rats. We found that frequency band divisions varied both across vigilance states and brain regions. In particular, theta oscillations during REM sleep were subdivided into two bands, 5–7 and 8–11 Hz corresponding to the tonic and phasic stages, respectively. The spindle activities of SWS were different along the anterior-posterior axis, lower oscillations (~16 Hz) in frontal regions and higher in parietal (~21 Hz). The delta and theta activities co-varied in the visual and auditory cortex during wakeful rest. In addition, power spectra of beta oscillations were significantly decreased in association cortex during REM sleep compared with wakeful rest. These results provide us some new insights into understand the brain oscillations across vigilance states, and also indicate that the spatial factor should not be ignored when considering the frequency band divisions in rats. PMID:27536231

  8. Classification of intelligence quotient via brainwave sub-band power ratio features and artificial neural network.

    Science.gov (United States)

    Jahidin, A H; Megat Ali, M S A; Taib, M N; Tahir, N Md; Yassin, I M; Lias, S

    2014-04-01

    This paper elaborates on the novel intelligence assessment method using the brainwave sub-band power ratio features. The study focuses only on the left hemisphere brainwave in its relaxed state. Distinct intelligence quotient groups have been established earlier from the score of the Raven Progressive Matrices. Sub-band power ratios are calculated from energy spectral density of theta, alpha and beta frequency bands. Synthetic data have been generated to increase dataset from 50 to 120. The features are used as input to the artificial neural network. Subsequently, the brain behaviour model has been developed using an artificial neural network that is trained with optimized learning rate, momentum constant and hidden nodes. Findings indicate that the distinct intelligence quotient groups can be classified from the brainwave sub-band power ratios with 100% training and 88.89% testing accuracies.

  9. Design of a LNA in the frequency band 1.8-2.2GHz in 0.13μm CMOS Technology

    Directory of Open Access Journals (Sweden)

    E. Di Gioia

    2005-01-01

    Full Text Available The subject of this work is a low noise amplifier (LNA, operating in the frequency range 1.8-2.1GHz. The CMOS 0.13μm technology is used in respect to the low cost of the final device. Among the specifications, a variable gain and an adjustable working frequency are required. In particular, four different working modes are provided: 1.8, 1.9 and 2.1GHz high gain and 2.1GHz low gain. The amplifier is designed to be used as first stage of a receiver for mobile telephony. For this reason low power consumption is taken into consideration (low supply voltage and low drain currents. A simple digital circuit, integrated on-chip, is used to select the operating mode of the LNA by means of two input pins. A Noise figure of 1dB is obtained with a supply voltage of 0.8V.

  10. Radar rainfall estimation for the post-event analysis of a Slovenian flash-flood case: application of the mountain reference technique at C-band frequency

    Directory of Open Access Journals (Sweden)

    L. Bouilloud

    2009-01-01

    Full Text Available This article is dedicated to radar rainfall estimation for the post-event analysis of a Slovenian flash flood that occurred on 18 September 2007. The utility of the Mountain Reference Technique is demonstrated to quantify rain attenuation effects that affect C-band radar measurements in heavy rain. Maximum path-integrated attenuation between 15 and 20 dB were measured thanks to mountain returns for path-averaged rain rates between 10 and 15 mm h−1 over a 120-km path. The proposed technique allowed estimation of an effective radar calibration correction factor, assuming the reflectivity-attenuation relationship to be known. Screening effects were quantified using a geometrical calculation based on a digitized terrain model of the region. The vertical structure of the reflectivity was modelled with a normalized apparent vertical profile of reflectivity. Implementation of the radar data processing indicated that: (1 attenuation correction using the Hitschfeld Bordan algorithm allowed obtaining satisfactory radar rain estimates (Nash criterion of 0.8 at the event time scale; (2 due to the attenuation equation instability, it is however compulsory to limit the maximum path-integrated attenuation to be corrected to about 10 dB; (3 the results also proved to be sensitive on the parameterization of reflectivity-attenuation-rainrate relationships. The convective nature of the precipitation explains the rather good performance obtained. For more contrasted rainy systems with convective and stratiform regions, the combination of the vertical (VPR and radial (attenuation, screening sources of heterogeneity yields a still very challenging problem for radar quantitative precipitation estimation at C-band.

  11. Study on Radio Frequency Interference Signal Analysis and Suppression in P Band SAR%P波段SAR射频干扰信号分析及抑制方法研究

    Institute of Scientific and Technical Information of China (English)

    丁斌; 梁兴东; 向茂生

    2012-01-01

    分析了实测P波段SAR静默接收数据,研究了模拟电视信号的频谱特性.针对P波段SAR回波中的模拟电视干扰信号,提出了一种新的干扰抑制方法.通过在时域拼接多个脉冲的回波数据增加模拟电视信号的观测时间以提高频率分辨率,进而在距离频域对其准确识别.根据模拟电视信号的频谱特征,在距离频域构造滤波器组滤除模拟电视信号的离散谱线,保留了谱线间SAR回波信号的频谱分量.实际回波数据的成像处理结果验证了方法的有效性.%Both P band SAR received silent data and spectrum characteristics of analog television signal are analyzed. In order to suppress analog television signals in P band SAR echoes, a novel interference suppression algorithm is proposed. By splicing multi-pulse SAR echoes in time domain, high frequency resolution of analog television signal can be obtained. Therefore the analog television signal can be identified accurately. By designing filter bank in range-frequency domain according to spectrum characteristics of analog television signals, the discrete spectrum lines of analog television signals are removed and the spectrum of SAR echoes between these discrete spectrum lines are saved. Finally, the proposed algorithm is verified by processing real P band SAR data.

  12. Temperature non-destructive testing by microwave radiometry: reduction of the frequency bandwidth; Controle non destructif de temperature par radiometrie micro-onde a bande etroite

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, L.; Vanoverschelde, C.; Sozanski, J.P.; Chive, M. [IEMN-UMR CNRS 9929, Dept. Hyperfrequences et Semi-Conducteurs, 59 - Villeneuve d' Ascq (France)

    1999-07-01

    Temperature is an important parameter for industrial process control. With the usual methods we obtain only an invasive or superficial information about temperature. Microwave radiometry is a non-invasive way to know the temperature within dissipative body. This paper presents the design of a new radiometer. With this system, the radiometric temperature is independent of the reflection coefficient of the captor. A simplified calibration takes into account insertion losses of the microwave elements. Radiometer frequency bandwidth has been greatly reduced and we present the first results. (authors)

  13. 带锯条掉齿前后横向振动位移及主频率变化规律%Horizontal Vibration Displacement and Main Frequency Variation of Band Saw Blade before and after Dropping Tooth

    Institute of Scientific and Technical Information of China (English)

    高金贵; 张健; 李辉; 吴俊华; 赵洪刚; 齐华春; 姜兆方

    2016-01-01

    Based on MJ345A woodworking band saw machine as the research object, the transverse vibration displacement of the saw blade was tested by using vibration analyzer under no-load and vibration signal acquisition, processing, analysis software. The vibration displacement and main modal frequency of different blades under the different conditions were found out through transverse vibration displacement of the saw blade and analysis of the power spectrum. The orthogonal experiment analysis showed that saw wheel spindle speed is the most significant factor impacting on the saw blade transverse vibration displacement,followed by the tension of saw blade,belt tension is not obvious. Analysis of band saw blade before and after dropping teeth showed that if the measuring range of transverse vibration displacement of band saw blade is in 0. 56~0. 68μm microns,and the vibration in 450~465 Hz frequency range,the saw blade had at least two teeth,new band saw blade need to be replaced in a timely manner in order to ensure the safety and cutting sawing quality;Then horizontal vibration displacement and frequency variation of band saw blade before and after dropping tooth have been clear. Research results can provide preliminary research and criterion of preliminary basis for sufficient and reasonable using band saw blade in the process of production,processing quality serious decline and the occurrence of the phenomenon such as endangering the personal safety accident,timely replacement blade.%以MJ345A型木工带锯机为研究对象,在空载下利用振动分析仪和振动信号采集、处理、分析软件对带锯条的横向振动进行测试及信号采集,通过锯条横向振动位移、自功率谱分析,找出不同条件下锯条振动位移和主振型频率的变化规律.通过正交试验分析可知:锯轮主轴转速是对锯条横向振动位移影响最为显著的因素,其次为锯条张紧力,皮带张紧力为不明显因素.对带

  14. Evaluation of the Association of Menopausal Status with Delta and Beta EEG Activity during Sleep

    Science.gov (United States)

    Campbell, Ian G.; Bromberger, Joyce T.; Buysse, Daniel J.; Hall, Martica H.; Hardin, Kimberly A.; Kravitz, Howard M.; Matthews, Karen A.; Rasor, Marianne O'Neill; Utts, Jessica; Gold, Ellen

    2011-01-01

    Study Objectives: Women report increasing sleep difficulties during menopause, but polysomnographic measures do not detect sleep disturbances. We examined whether two spectral analysis sleep measures, delta and beta power, were related to menopausal status. Design: The Study of Women's Health Across the Nation (SWAN) Sleep Study compared cross-sectionally spectral sleep measures in women in different stages of menopause. Setting: Sleep EEG was recorded in the participants' homes with ambulatory recorders. Participants: A multi-ethnic cohort of premenopausal and early perimenopausal (n = 189), late perimenopausal (n = 73), and postmenopausal (n = 59) women. Measurements: EEG power in the delta and beta frequency bands was calculated for all night NREM and all night REM sleep. Physical, medical, psychological, and socioeconomic data were collected from questionnaires and diaries. Results: Beta EEG power in NREM and REM sleep in late perimenopausal and postmenopausal women exceeded that in pre- and early perimenopausal women. Neither all night delta power nor the trend in delta power across the night differed by menopausal status. In a multivariate model that controlled for the physical, demographic, behavioral, psychological, and health-related changes that accompany menopause, beta power in both NREM and REM sleep EEG was significantly related to menopausal status. The frequency of hot flashes explained part but not all of the relation of beta power to menopausal status. Conclusions: Elevated beta EEG power in late perimenopausal and postmenopausal women provides an objective measure of disturbed sleep quality in these women. Elevated beta EEG activity suggests that arousal level during sleep is higher in these women. Citation: Campbell IG; Bromberger JT; Buysse DJ; Hall MH; Hardin KA; Kravitz HM; Matthews KA; Rasor MO; Utts J; Gold E. Evaluation of the association of menopausal status with delta and beta EEG activity during sleep. SLEEP 2011;34(11):1561-1568. PMID

  15. Theoretical Simulation for Identical Bands

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Jing; CHEN Yong-Shou; GAO Zao-Chun

    2004-01-01

    @@ The frequency of occurrence of identical bands is studied by analysing a large number of rotational bands calculated with the reflection asymmetric shell model, and the statistical properties of identical bands indicated in all the experimental observations are reproduced within the mean field approximation and beyond mean field treatment, such as angular momentum projection. The distributions of the calculated J(2), Eγ and the fractional change of J(2) are discussed.

  16. Development of Wide Band Feeds

    Science.gov (United States)

    Ujihara, H.; Ichikawa, R.

    2012-12-01

    Wide Band feeds are being developed at NICT, NAOJ, and some universities in Japan for VLBI2010, SKA, and MARBLE. SKA, the Square Kilometre Array, will comprise thousands of radio telescopes with square kilometer aperture size for radio astronomy. MARBLE consists of small portable VLBI stations developed at NICT and GSI in Japan. They all need wide band feeds with a greater than 1:10 frequency ratio. Thus we have been studying wide band feeds with dual linear polarization for these applications.

  17. Thermal performance and radio-frequency transmissivity of candidate ablation materials for S-band antenna window application on manned spacecraft

    Science.gov (United States)

    Tillian, D. J.; Cubley, H. D.

    1970-01-01

    A test program was conducted in the MSC 1.5 MW arc-heated facility to evaluate the thermal performance of ablation materials having potential application as radio frequency windows. These tests were conducted for the improvement of omnidirectional antenna operating characteristics during atmospheric reentry. Since a full scale model of the Apollo command service module was available for antenna tests, this mockup was used as a basic for the tests. Test models were subjected to heating conditions simulating the nominal lunar return trajectory (AS-501) and the design trajectories, high heat load and high heating rate. RF measurements were made before and after the arc jet tests to measure attenuation effects due to the thermal degradation of the materials under consideration. The test program demonstrated that additional development is required in materials technology to achieve an ablative system with both good RF transmission characteristics and thermal-structural integrity.

  18. 双频宽带大型微带反射阵天线设计%Design on Double Frequency and Wide Band Microstrip Reflectarray Antenna

    Institute of Scientific and Technical Information of China (English)

    李小秋; 郑雪飞; 杨成

    2012-01-01

    微带反射阵天线在性能上最主要的缺陷就是窄带,一般情况下其带宽小于5%,对电大口径短焦距馈电时更窄。本文设计并制作出一种由L波段和C波段两个反射面天线组成的6m×2m薄膜双频微带反射阵天线,两个频段的天线共用一层膜面。对该天线的电性能进行了测试,测试结果表明:该天线两个频段的相对带宽均大于10%(副瓣电平≤-18dB)。该天线具有折叠、可展开的结构特征,可以在卫星或航天器上广泛应用。%The main limitation to microstrip reflectarray antenna performance is the narrow bandwidth. It is generally lower than 5 percent and even less for large microstrip reflectarray antenna. In this paper, the double frequency and wideband microstrip reflectarray antenna was designed, fabricated and tested, which comprised of an L waveband reflecting surface antenna and a C waveband reflecting surface antenna in a same plane. Testing results indicate that the frequency bandwidth can reach 10% for sidelobe level less than or equal to -18dB. The microstrip reflectarray antenna has the characteristics of easily folded and portability, which will be widely applied in satellite or spacecraft.

  19. Narrow-Band Microwave Filters

    Directory of Open Access Journals (Sweden)

    A.V. Strizhachenko

    2010-01-01

    Full Text Available Original design of the narrow-band compact filters based on the high-quality waveguide-dielectric resonator with anisotropic materials has been presented in this work. Designed filters satisfy the contradictory requirements: they provide the narrow frequency band (0.05 ÷ 0.1 % of the main frequency f0 and the low initial losses α0 ≤ 1 dB.

  20. Gastric Banding

    Science.gov (United States)

    ... gastric banding before deciding to have the procedure. Advertisements for a device or procedure may not include ... feeds Follow FDA on Twitter Follow FDA on Facebook View FDA videos on YouTube View FDA photos ...

  1. Interpretation of the distortion of ground-penetrating radar propagated and reflected waves - development of a multi-frequency tomography; Interpretation de la distorsion des signaux georadar propages et reflechis. Developpement d'une tomographie par bandes de frequence

    Energy Technology Data Exchange (ETDEWEB)

    Hollender, F

    1999-07-01

    Within the framework of research for waste disposal in deep geological formations, the French agency for nuclear waste management (ANDRA) has to dispose of non-destructive investigation methods to characterize the medium. Ground penetrating radar (GPR) could be used for this purpose in the case of granitic sites. The work presented here deals with this geophysical method. The classical interpretation of GPR data consists in the localization of geological discontinuities by signal amplitude or arrival time analysis. The main objective of our studies is the interpretation of the radar wave distortion (due to propagation and reflection phenomena), not only to localize discontinuities but also to contribute to their identification. Three preliminary studies have been carried out in order to understand on the one hand, the complexity of the electromagnetic phenomena in the geological medium at radar frequency, and on the other hand, the radar equipment constraints. First, the dispersion and the attenuation characterized by a Q variable factor of the GPR waves are shown with the support of dielectric laboratory measurements. A model, which only requires three parameters, is proposed in order to describe this behavior. Second, the radiation patterns of borehole radar antenna are studied. We show that the amplitude and frequency content of the emitted signal are variable versus the emission angle. An analytical method is proposed to study these phenomena. Finally, instrumental drifts of GPR equipment are studied. Emission time, sampling frequency and amplitude fluctuations are described. These elements are taken into account for the processing of propagated signals by tomographic inversion. Medium anisotropy and borehole trajectory errors are inserted in algorithms in order to cancel artifacts which compromised the previous interpretation. A pre-processing method, based on wave separation algorithm, is applied on data in order to increase tomogram resolution. A new

  2. Optimal frequency band extraction method based on wavelet packet and entropy criterion%基于小波包和熵准则的最优频段提取方法

    Institute of Scientific and Technical Information of China (English)

    李明爱; 马建勇; 杨金福

    2012-01-01

    The implementation of the consistency between motor intention and practical rehabilitation exercise based on brain-computer interface technology is necessary to improve the rehabilitation effect for people with dyskinesia. Taking the flexion and extension motor imagery of index finger as an example, the feature extraction method for the electroencephalogram produced by the same or similar body parts under different motor imagery tasks (labelled as EEGs) is studied in this paper. Aiming at the characteristics of EEGs, including its weak phenomenon of event-related desynchronization ( ERD) and large individual differences of time and frequency bands where ERD appears, an optimal frequency band extraction method is proposed based on wavelet packet decomposition and entropy criterion. The EEGs of the flexion and extension motor imagery of index finger are decomposed with wavelet packet analysis firstly. Then, the separability values of the characteristic frequency bands are measured with entropy criterion. Furthermore , some clearer wavelet packets are selected to form a combination, and corresponding wavelet packet coefficients are used to construct the feature vectors. Lastly, the optimal band is obtained with support vector machine. Experiment results show that the feature extraction method can choose the feature bands with large difference in ERD phenomenon of the EEGs, and the highest classification accuracy is 81. 75% , which verifies the correctness and validity of the presented method.%为实现运动功能障碍患者的运动意愿和基于脑机接口技术的实际康复运动的一致性,进一步改善康复效果,以想象右手食指屈伸运动为例,对身体相同或相近部位的不同运动想象方式产生的脑电信号(记为EEGs)的特征提取方法进行研究.针对食指屈伸运动想象EEGs的事件相关去同步化现象(event-related desynchronization,ERD)不显著及发生的时间及频段的个体差异等特点,提出了基于

  3. 高度表宽多普勒频宽回波研究%Study of Altimeter Wide Doppler Frequency Band Echo

    Institute of Scientific and Technical Information of China (English)

    刘浩淼; 卞树檀; 朱守保

    2012-01-01

    分析了PD雷达高度表的地回波特性。总结了高度表的工作特征,通过网格映像法借助数字地图思想建立了地面的距离-多普勒关系。考虑回波的影响因素,如散射系数、天线模型等,通过Matlab建模仿真分析了高度表回波的时域和频域特征。研究结果对研制和地面测试弹载雷达高度表提供了技术支持。%This paper analyzes the features of the PD radar altimeter.It summarizes the performance characteristics of the altimeter.Based on the idea of the digital map,it sets up the ground distance-doppler relation by the grid method.Considering the effects of the crossing factor,such as the scattering parameter and antenna model,a simulation model is built with Matlab,which can analyze the features of the time-zone and frequency-zone.The result can provide technical support to the development and test of the altimeter for missiles.

  4. 47 CFR 95.1401 - Frequency.

    Science.gov (United States)

    2010-10-01

    ... SERVICES Personal Locator Beacons (PLB). § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of...

  5. Global frequency and intensity analysis of the ν10/ν7/ν4/ν12 band system of 12C2H4 at 10 μm using the D2h Top Data System

    Science.gov (United States)

    Alkadrou, A.; Bourgeois, M.-T.; Rotger, M.; Boudon, V.; Vander Auwera, J.

    2016-10-01

    A global frequency and intensity analysis of the infrared tetrad of 12C2H4 located in the 600 - 1500cm-1 region was carried out using the tensorial formalism developed in Dijon for X2Y4 asymmetric-top molecules. It relied on spectroscopic information available in the literature and retrieved from high-resolution Fourier transform infrared spectra recorded in Brussels in the frame of either the present or previous work. In particular, 645 and 131 line intensities have been respectively measured for the weak ν10 and ν4 bands. Including the Coriolis interactions affecting the upper vibrational levels 101, 71, 41 and 121, a total of 10 757 line positions and 1645 line intensities have been assigned and fitted with global root mean square deviations of 2.6 ×10-4cm-1 and 2.5%, respectively. Relying on the results of the present work and available in the literature, a list of parameters for 65 776 lines in the ν10, ν7, ν4 and ν12 bands of 12C2H4 was generated. To the best of our knowledge, this is the first time that a global intensity analysis is carried out in this range of the ethylene spectrum.

  6. 高灵敏度宽频带阵列式仿生矢量水听器研究%Research on the Arrayed Bionic Vector Hydrophone with High Sensitivity and Wide Frequency Band

    Institute of Scientific and Technical Information of China (English)

    宋小鹏; 薛晨阳; 张国军; 刘林仙

    2012-01-01

    针对MEMS仿生矢量水听器灵敏度和频带相互制约,不能同时满足宽频带高灵敏度测量的问题,在单个MEMS矢量水听器的基础上,设计了由四个单元构成的2×2单片集成微敏感结构阵列,实现了水听器的高灵敏度和宽频带.通过理论分析和ANSYS仿真分析,确定阵列微结构的尺寸,采用硅微机械加工工艺完成了阵列微结构的加工,最后在水声一级计量站对封装好的水听器进行了灵敏度和指向性校准测试.测试结果表明:该阵列式仿生矢量水听器未加前置放大时灵敏度达到-189 dB,频响范围20~5 000 Hz,具有良好的“8”字型指向性.%The MEMS bionic vector hydrophone, for the mutual restriction of its sensitivity and frequency band, cannot meet the requirements for the measurement of high sensitivity and wide band simultaneously. In order to solve the problem, a kind of 2 X 2 single chip integrated micro sensitive structure array consisting of four units was designed to realize the high sensitivity and wide band of the hydrophone based on a single MEMS vector hydrophone. Then, the size of the micro structure for the array was confirmed through the theoretical and ANSYS simulation analysis, and the process for the micro structure for the array was completed by adopting the process technology of the micro-machine. Finally, the test for the sensitivity and directional calibration was conducted for a sealed hydrophone at the underwater acoustic calibration laboratory. The test result indicates that the array type bionic hydrophone without the installment of a preamplifier has the sensitivity of - 189 dB, the frequency range of 20 - 5 000Hz and a good directionality in the shape of "8".

  7. Frequency and Sensitivity of Extended Spectrum Beta-Lactamase Positive Organisms in a Secondary and Tertiary Level Hospital Network in Dhaka

    Directory of Open Access Journals (Sweden)

    Shah Md Zahurul Haque Asna

    2015-05-01

    Full Text Available Background: Extended spectrum β-lactamase (ESBL positive organisms are now a global health concern including in Bangladesh. These are associated with treatment failure, increased morbidity and mortality and increased health care costs. In this study, frequency of ESBL positive organisms in some health care centres in Dhaka city has been observed and their current status of antibiogram has also been observed. Objective: To observe the current status of antibiogram of ESBL positive organisms. Materials and Methods: This cross-sectional study was done in the Department of Microbiology, Bangladesh Institute of Health Sciences (BIHS General Hospital, Dhaka, Bangladesh from March, 2012 to February, 2013. Only E. coli and Klebsiella spp. from pus and urine specimens were included in this study. Isolation, identification and antibiotic sensitivity of the organisms were done by standard procedures. Results: Organisms (Escherichia coli and Klebsiella spp. isolated from urine and pus collected from different sites of 472 subjects were studied. Predominant organisms were Escherichia coli (82.8% and remaining 17.2% were Klebsiella spp. ESBL positive organisms were higher in Escherichia coli (54.5% than in Klebsiella spp. (44.4% and higher in pus (77.0% than in urine (49.1% isolates. Imipenem is the most effective drug for treating ESBL positive organisms followed by colistin, tigecycline and piperacillin/tazobactam. Conclusion: Imipenem, colistin, tigecycline and piperacillin/tazobactam drugs should be kept reserved and used only when other effective drugs are not available so that emergence of resistance against these drugs is deferred. While reporting the culture and sensitivity tests, the ESBL positive organisms should be pointed out with comment like this – “The organisms are ESBL positive and resistant to penicillins, cephalosporins and monobactams”.

  8. Continuous and Jump Betas: Implications for Portfolio Diversification

    Directory of Open Access Journals (Sweden)

    Vitali Alexeev

    2016-06-01

    Full Text Available Using high-frequency data, we decompose the time-varying beta for stocks into beta for continuous systematic risk and beta for discontinuous systematic risk. Estimated discontinuous betas for S&P500 constituents between 2003 and 2011 generally exceed the corresponding continuous betas. We demonstrate how continuous and discontinuous betas decrease with portfolio diversification. Using an equiweighted broad market index, we assess the speed of convergence of continuous and discontinuous betas in portfolios of stocks as the number of holdings increase. We show that discontinuous risk dissipates faster with fewer stocks in a portfolio compared to its continuous counterpart.

  9. Ku/Ka-band electrically-scanned line array for tri-band cloud and precipitation radar applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spaceborne radar system that operates simultaneously at multiple frequency bands from microwave through millimeter-wave frequencies can exploit the largely...

  10. 基于两级字典与分频带字典的图像超分辨率算法%Single Image Super-resolution Algorithm Based on Two-stage and Multi-frequency-band Dictionaries

    Institute of Scientific and Technical Information of China (English)

    练秋生; 张钧芹; 陈书贞

    2013-01-01

    The conventional super-resolution algorithms on sparse representation reconstruct the high resolution image using one-stage high/low resolution dictionary pairs with inadequate detail information.In order to recover detail information as much as possible,two-stage dictionaries are explored in this paper.Then we train jointly multiple-frequency-band dictionaries consisting of low frequency (LF) dictionaries,middle frequency (MF) dictionaries and high frequency (HF) dictionaries,and simultaneously exploit the prediction relation of LF component,MF component and HF component to recover middle and high frequency information.Considering that there are many repetitive structures in the natural image,nonlocal self-similarity information is combined properly with iterative back-projection procedure to post-process the image.Experimental results demonstrate that the proposed algorithm has remarkable improvement in peak signal-to-noise ratio,structural similarity and visual quality compared with the other learning-based algorithms.%常规基于稀疏表示的超分辨率算法使用一级高低分辨字典重构图像,恢复细节信息不充分.本文利用两级字典恢复尽可能多的细节信息;然后构造联合低频字典、中频字典、高频字典的分频带字典,利用图像低频、中频、高频三者之间的预测关系,恢复图像中的高频信息.利用图像的非局部相似性,将其与迭代反向投影算法相结合,进行图像的后处理.实验结果表明,与其他几种基于学习的算法相比,本算法无论是在峰值信噪比、结构相似性指标,还是视觉效果上都有显著的提高.

  11. Frequency and origin of haplotypes associated with the beta-globin gene cluster in individuals with trait and sickle cell anemia in the Atlantic and Pacific coastal regions of Colombia

    Directory of Open Access Journals (Sweden)

    Cristian Fong

    2013-01-01

    Full Text Available Sickle cell anemia is a genetic disease with high prevalence in people of African descent. There are five typical haplotypes associated with this disease and the haplotypes associated with the beta-globin gene cluster have been used to establish the origin of African-descendant people in America. In this work, we determined the frequency and the origin of haplotypes associated with hemoglobin S in a sample of individuals with sickle cell anemia (HbSS and sickle cell hemoglobin trait (HbAS in coastal regions of Colombia. Blood samples from 71 HbAS and 79 HbSS individuals were obtained. Haplotypes were determined based on the presence of variable restriction sites within the β-globin gene cluster. On the Pacific coast of Colombia the most frequent haplotype was Benin, while on the Atlantic coast Bantu was marginally higher than Benin. Eight atypical haplotypes were observed on both coasts, being more diverse in the Atlantic than in the Pacific region. These results suggest a differential settlement of the coasts, dependent on where slaves were brought from, either from the Gulf of Guinea or from Angola, where the haplotype distributions are similar. Atypical haplotypes probably originated from point mutations that lost or gained a restriction site and/or by recombination events.

  12. Frequency and origin of haplotypes associated with the beta-globin gene cluster in individuals with trait and sickle cell anemia in the Atlantic and Pacific coastal regions of Colombia.

    Science.gov (United States)

    Fong, Cristian; Lizarralde-Iragorri, María Alejandra; Rojas-Gallardo, Diana; Barreto, Guillermo

    2013-12-01

    Sickle cell anemia is a genetic disease with high prevalence in people of African descent. There are five typical haplotypes associated with this disease and the haplotypes associated with the beta-globin gene cluster have been used to establish the origin of African-descendant people in America. In this work, we determined the frequency and the origin of haplotypes associated with hemoglobin S in a sample of individuals with sickle cell anemia (HbSS) and sickle cell hemoglobin trait (HbAS) in coastal regions of Colombia. Blood samples from 71 HbAS and 79 HbSS individuals were obtained. Haplotypes were determined based on the presence of variable restriction sites within the β-globin gene cluster. On the Pacific coast of Colombia the most frequent haplotype was Benin, while on the Atlantic coast Bantu was marginally higher than Benin. Eight atypical haplotypes were observed on both coasts, being more diverse in the Atlantic than in the Pacific region. These results suggest a differential settlement of the coasts, dependent on where slaves were brought from, either from the Gulf of Guinea or from Angola, where the haplotype distributions are similar. Atypical haplotypes probably originated from point mutations that lost or gained a restriction site and/or by recombination events. PMID:24385850

  13. 780/868/915 MHz frequency bands low power current reusing frequency synthesizer for wireless sensor network%780/868/915MHz频段无线传感器网络低功耗电流复用频率综合器

    Institute of Scientific and Technical Information of China (English)

    阴亚东; 张利红; 孟海涛; 杜占坤; 阎跃鹏

    2011-01-01

    A low power frequency synthesizer suited for wireless sensor network transceiver in 780 (China)/868( Europe)/915 ( USA) MHz frequency bands is proposed. The current reusing technique is adopted to make the voltage controlled oscillator (VCO) and divider share a common bias current so to cut down the power budget. A novel lock detector with programmable locked-detecting thresholds is integrated in frequency synthesizer to detect the locked time. Frequency synthesizer was fabricated in 0.18 u,m CMOS (complementary metal oxide semiconductor) technology and the measurement was carried out. Test results show that the frequency rang of synthesizer is 770 - 930 MHz; when the output frequency is 868 MHz, the phase noise is - 87 dBc/Hz in band, with - 98 dBc/Hz @ 100 kHz and - 124 dBc/Hz@ 1 MHz; the measured locked time is 91 -112 u,s with different locked-detecting thresholds; the total current of synthesizer is 3.9 mA under 1.8 V supply.%提出了一种适用于780(中国)/868(欧洲)/915(美国)MHz频段无线传感器网络收发机的低功耗频率综合器,采用电流复用技术使压控振荡器(VCo)和分频器共享偏置电流从而降低了功耗.集成了新型锁定检测门限可编程的锁定检测器用于锁相时间指示.频率综合器采用0.18 μm CMOS工艺进行验证和测试.测试结果显示:频率覆盖范围约为770 ~930MHz;输出信号频率为868 MHz时带内相位噪声为- 87 dBc/Hz,频偏100 kHz和1 MHz处相位噪声分别为-98和- 124 dBc/Hz;在不同锁定检测门限下测得锁定时间为91~112 μs;在工作电压为1.8V时,频率综合器工作电流约为3.9mA.

  14. Transient Global Amnesia Deteriorates the Network Efficiency of the Theta Band

    Science.gov (United States)

    Yi, SangHak; Lim, Jae-Sung; Jang, Jae-Won; Im, Chang-Hwan; Kim, SangYun

    2016-01-01

    Acute perturbation of the hippocampus, one of the connector hubs in the brain, is a key step in the pathophysiological cascade of transient global amnesia (TGA). We tested the hypothesis that network efficiency, meaning the efficiency of information exchange over a network, is impaired during the acute stage of TGA. Graph theoretical analysis was applied to resting-state EEG data collected from 21 patients with TGA. The EEG data were obtained twice, once during the acute stage ( 2 months after symptom onset) of TGA. Characteristic path lengths and clustering coefficients of functional networks constructed using phase-locking values were computed and normalized as a function of the degree in the delta, theta, alpha, beta 1, beta 2 and gamma frequency bands of the EEG. We investigated whether the normalized characteristic path length (nCPL) and normalized clustering coefficients (nCC) differed significantly between the acute and resolved stages of TGA at each frequency band using the Wilcoxon signed-rank test. For networks where the nCPL or nCC differed significantly between the two stages, we also evaluated changes in the connections of the brain networks. During the acute stage of TGA, the nCPL of the theta band networks with mean degrees of 8, 8.5, 9 and 9.5 significantly increased (P < 0.05). During the acute stage, the lost edges for these networks were mostly found between the anterior (frontal and anterior temporal) and posterior (parieto-occipital and posterior temporal) brain regions, whereas newly developed edges were primarily found between the left and right frontotemporal regions. The nCC of the theta band with a mean degree of 5.5 significantly decreased during the acute stage (P < 0.05). Our results indicate that TGA deteriorates the network efficiency of the theta frequency band. This effect might be related to the desynchronization between the anterior and posterior brain areas. PMID:27741293

  15. Unexpected pattern of beta-globin mutations in beta-thalassaemia patients from northern Portugal

    OpenAIRE

    Cabeda, J.; Correia, C.; Estevinho, A.; Simões, C.; Amorim, M; L. Pinho; Justiça, B

    1999-01-01

    We characterized the genetic nature of beta-thalassaemia in northern Portugal. Of the 164 patients studied three were beta-thalassaemia major cases (one IVS-1-6/beta degrees 39 and two homozygous IVS-1-110). The analysis of the frequency of each mutation in the families revealed that the codon 6(-A) mutation was unexpectedly frequent (40%) and associated with the beta-globin haplotype E, and not with the usual European and North African CD6(-A) haplotypes. In contrast, the frequency of IVS-1-...

  16. 氧化钒薄膜太赫兹波段频率特性研究%Study on frequency characteristics of VO_x thin films in THz band

    Institute of Scientific and Technical Information of China (English)

    陈涛; 胡明; 梁继然; 后顺保; 吕志军; 栗力

    2011-01-01

    Vanadium oxide(VOx) thin films were prepared on silicon substrates by the direct current facing targets magnetron sputtering,and these films have optical switching performance in terahertz(THz) band.The X-ray photoelectron spectroscopy and scanning electronic microscopy(SEM) were used to measure the component and investigate the morphology of VOx thin films.In addition,the photo-induced phase transition properties of VOx were tested by the THz time-domain spectroscopy system(TDS).In the experiment,VOx thin films have an obvious photo-induced phase transition in THz band,when it is under laser excitation of 532 nm,and with the overall valence of vanadium increasing,the frequency of THz transmission peak gradually decreases.%利用直流对靶磁控溅射镀膜法,在Si衬底上制备出在太赫兹(THz)波段具有开关性能的氧化钒(VOx)薄膜。用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)方法对VOx薄膜的组份和形貌进行表征。利用THz时域频谱系统(THz-TDS)对VOx薄膜的光致相变性能进行测试。实验表明,VOx薄膜在波长532 nm连续激光照射下具有明显的光致相变特性,且随着薄膜中V元素总体价态的升高,THz透射率达到峰值时的频率逐渐降低。

  17. Frequency specific modulation of human somatosensory cortex

    Directory of Open Access Journals (Sweden)

    Matteo eFeurra

    2011-02-01

    Full Text Available Oscillatory neuronal activities are commonly observed in response to sensory stimulation. However, their functional roles are still the subject of debate. One way to probe the roles of oscillatory neural activities is to deliver alternating current to the cortex at biologically relevant frequencies and examine whether such stimulation influences perception and cognition. In this study, we tested whether transcranial alternating current stimulation (tACS over the primary somatosensory cortex (SI could elicit tactile sensations in humans in a frequency dependent manner. We tested the effectiveness of tACS over SI at frequency bands ranging from 2 to 70 Hz. Our results show that stimulation in alpha (10-14 Hz and high gamma (52-70 Hz frequency range produces a tactile sensation in the contralateral hand. A weaker effect was also observed for beta (16-20 Hz stimulation. These findings highlight the frequency-dependency of effective tACS over SI with the effective frequencies corresponding to those observed in previous EEG/MEG studies of tactile perception. Our present study suggests that tACS could be used as a powerful online stimulation technique to reveal the causal roles of oscillatory brain activities.

  18. Estrogen receptor beta and 2-arachydonoylglycerol mediate the suppressive effects of estradiol on frequency of postsynaptic currents in gonadotropin-releasing hormone neurons of metestrous mice: an acute slice electrophysiological study

    Directory of Open Access Journals (Sweden)

    Flóra eBálint

    2016-03-01

    Full Text Available Gonadotropin-releasing hormone (GnRH neurons are controlled by 17β-estradiol (E2 contributing to the steroid feedback regulation of the reproductive axis. In rodents, E2 exerts a negative feedback effect upon GnRH neurons throughout the estrus-diestrus phase of the ovarian cycle. The present study was undertaken to reveal the role of estrogen receptor subtypes in the mediation of the E2 signal and elucidate the downstream molecular machinery of suppression. The effect of E2 administration at low physiological concentration (10 pM on GnRH neurons in acute brain slices obtained from metestrous GnRH-GFP mice was studied under paradigms of blocking or activating estrogen receptor subtypes and interfering with retrograde 2-arachydonoylglycerol (2-AG signaling. Whole-cell patch clamp recordings revealed that E2 significantly diminished the frequency of spontaneous postsynaptic currents (sPSCs in GnRH neurons (49. 62±7.6% which effect was abolished by application of the ERα/β blocker Faslodex (1 µM. Pretreatment of the brain slices with cannabinoid receptor type 1 (CB1 inverse agonist AM251 (1 µM and intracellularly applied endocannabinoid synthesis blocker THL (10 µM significantly attenuated the effect of E2 on the sPSCs. E2 remained effective in the presence of TTX indicating a direct action of E2 on GnRH cells. The ERβ specific agonist DPN (10 pM also significantly decreased the frequency of miniature postsynaptic currents (mPSCs in GnRH neurons. In addition, the suppressive effect of E2 was completely blocked by the selective ERβ antagonist PHTPP (1 µM indicating that ERβ is required for the observed rapid effect of the E2. In contrast, the ERα agonist PPT (10 pM or the membrane-associated G protein-coupled estrogen receptor (GPR30 agonist G1 (10 pM had no significant effect on the frequency of mPSCs in these neurons. AM251 and THL significantly abolished the effect of E2 whereas AM251 eliminated the action of DPN on the mPSCs. These

  19. Alpha and beta EEG power reflects L-dopa acute administration in parkinsonian patients

    Science.gov (United States)

    Melgari, Jean-Marc; Curcio, Giuseppe; Mastrolilli, Francesca; Salomone, Gaetano; Trotta, Laura; Tombini, Mario; di Biase, Lazzaro; Scrascia, Federica; Fini, Rita; Fabrizio, Emma; Rossini, Paolo Maria; Vernieri, Fabrizio

    2014-01-01

    Aim: To evaluate the effect of an acute L-dopa administration on eye-closed resting state electroencephalographic (EEG) activity of cognitively preserved Parkinsonian patients. Methods: We examined 24 right-handed patients diagnosed as uncomplicated probable Parkinson’s disease (PD). Each patient underwent Unified Parkinson’s Disease Rating Scale (UPDRS)-part-III evaluation before and 60 min after an oral load of L-dopa-methyl-ester/carbidopa 250/25 mg. Resting condition eyes-closed EEG data were recorded both pre- and post L-dopa load. Absolute EEG power values were calculated at each scalp derivation for Delta, Theta, Alpha and Beta frequency bands. UPDRS scores (both global and subscale scores) and EEG data (power values of different frequency bands for each scalp derivation) were submitted to a statistical analysis to compare Pre and Post L-Dopa conditions. Finally, a correlation analysis was carried out between EEG spectral content and UPDRS scores. Results: Considering EEG power spectral analysis, no statistically significant differences arose on Delta and Theta bands after L-dopa intake. Conversely, Alpha and Beta rhythms significantly increased on centro-parietal scalp derivations, as a function of L-dopa administration. Correlation analysis indicated a significant negative correlation between Beta power increase on centro-parietal areas and UPDRS subscores (Rigidity of arms and Bradykinesia). A minor significant negative correlation was also found between Alpha band increase and resting tremor. Conclusions: Assuming that a significant change in EEG power spectrum after L-dopa intake may be related to dopaminergic mechanisms, our findings are consistent with the hypothesis that dopaminergic defective networks are implicated in cortical oscillatory abnormalities at rest in non-demented PD patients. PMID:25452725

  20. Alpha and beta EEG power reflects L-dopa acute administration in parkinsonian patients

    Directory of Open Access Journals (Sweden)

    Jean-Marc eMelgari

    2014-11-01

    Full Text Available Aim. To evaluate the effect of an acute L-dopa administration on eye-closed resting state electroencephalographic (EEG activity of cognitively preserved Parkinsonian patients. Methods. We examined 24 right-handed patients diagnosed as uncomplicated probable Parkinson’s disease (PD. Each patient underwent UPDRS-part-III evaluation before and 60 minutes after an oral load of L-dopa-methyl-ester/carbidopa 250/25 mg. Resting condition eyes-closed EEG data were recorded both pre- and post L-dopa load. Absolute EEG power values were calculated at each scalp derivation for Delta, Theta, Alpha and Beta frequency bands. UPDRS scores (both global and subscale scores and EEG data (power values of different frequency bands for each scalp derivation were submitted to a statistical analysis to compare Pre e Post L-Dopa conditions. Finally, a correlation analysis was carried out between EEG spectral content and UPDRS scores. Results. Considering EEG power spectral analysis, no statistically significant differences arose on Delta and Theta bands after L-dopa intake. Conversely, Alpha and Beta rhythms significantly increased on centro-parietal scalp derivations, as a function of L-dopa administration. Correlation analysis indicated a significant negative correlation between Beta power increase on centro-parietal areas and UPDRS subscores (Rigidity of arms and Bradykinesia. A minor significant negative correlation was also found between Alpha band increase and resting tremor. Conclusions. Assuming that a significant change in EEG power spectrum after L-dopa intake may be related to dopaminergic mechanisms, our findings are consistent with the hypothesis that dopaminergic defective networks are implicated in cortical oscillatory abnormalities at rest in non-demented PD patients.

  1. X-Band PLL Synthesizer

    Directory of Open Access Journals (Sweden)

    P. Kutin

    2006-04-01

    Full Text Available This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal from the frequency doubler is filtered by a band-pass filter and finally amplified by a single stage amplifier.

  2. Distributed coding of remote sensing image based on wavelet low frequency sub-band prediction%小波低频子带预测的遥感图像分布式编码

    Institute of Scientific and Technical Information of China (English)

    王相海; 秦铭爽; 付明哲; 程露露

    2012-01-01

    传感技术的不断发展使遥感图像的时间、空间和光谱分辨率不断提高,信息量日益增大,给遥感图像的存储和传输带来了极大挑战,传统图像编码策略难以适应这种基于上行的遥感图像应用需求.本文提出一种基于小波低频子带预测的分布式遥感图像编码方案,利用预测插值的方法得到用于解码Wyner-Ziv的辅助信息,图像的低频信息采用小波零树编码方案,而预测误差图像采用基于均匀量化和位平面的Turbo混合编码方案;在解码端,以预测误差图像的码流作为辅助信息,将其与图像的低频信息码流进行联合解码.实验结果表明,提出方法具有编码效率高、失真率小、压缩比高、抗误码性强和码流具有质量可分级等特性.%As the continuous development of sensor technology to improve spatial, temporal resolution and spectral resolution of remote sensing images and to increase the amount of information, thus the storage and transmission of remote sensing image has brought significant challenges, so traditional image coding strategy is difficult to adapt to the applications of remote sensing images based on the uplink demand. This paper presents a coding scheme which is based on wavelet low-frequency sub-band prediction of distributed remote sensing images, using interpolation prediction method to get the auxiliary information which is used to decode the Wyner-Ziv. Low-frequency information of images use embedded zerotree wavelet (EZW) coding scheme, while the prediction-error image use the Turbo hybrid coding scheme based on uniform quantization and the bit plane. At the decoder, the stream of prediction-error image is considered as an auxiliary information and the stream of low-frequency information are joint decoding. Experimental results show that the proposed method has high coding efficiency, small distortion, high compression ratio, strong ability of error control and scalable bit stream with

  3. Microstrip microwave band gap structures

    Indian Academy of Sciences (India)

    V Subramanian

    2008-04-01

    Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

  4. Cluster observations of high-frequency waves in the exterior cusp

    Directory of Open Access Journals (Sweden)

    Y. Khotyaintsev

    2004-07-01

    Full Text Available We study wave emissions, in the frequency range from above the lower hybrid frequency up to the plasma frequency, observed during one of the Cluster crossings of a high-beta exterior cusp region on 4 March 2003. Waves are localized near narrow current sheets with a thickness a few times the ion inertial length; currents are strong, of the order of 0.1-0.5μA/m2 (0.1-0.5mA/m2 when mapped to ionosphere. The high frequency part of the waves, frequencies above the electron-cyclotron frequency, is analyzed in more detail. These high frequency waves can be broad-band, can have spectral peaks at the plasma frequency or spectral peaks at frequencies below the plasma frequency. The strongest wave emissions usually have a spectral peak near the plasma frequency. The wave emission intensity and spectral character change on a very short time scale, of the order of 1s. The wave emissions with strong spectral peaks near the plasma frequency are usually seen on the edges of the narrow current sheets. The most probable generation mechanism of high frequency waves are electron beams via bump-on-tail or electron two-stream instability. Buneman and ion-acoustic instability can be excluded as a possible generation mechanism of waves. We suggest that high frequency waves are generated by electron beams propagating along the separatrices of the reconnection region.

  5. Modulation of EEG Theta Band Signal Complexity by Music Therapy

    Science.gov (United States)

    Bhattacharya, Joydeep; Lee, Eun-Jeong

    The primary goal of this study was to investigate the impact of monochord (MC) sounds, a type of archaic sounds used in music therapy, on the neural complexity of EEG signals obtained from patients undergoing chemotherapy. The secondary goal was to compare the EEG signal complexity values for monochords with those for progressive muscle relaxation (PMR), an alternative therapy for relaxation. Forty cancer patients were randomly allocated to one of the two relaxation groups, MC and PMR, over a period of six months; continuous EEG signals were recorded during the first and last sessions. EEG signals were analyzed by applying signal mode complexity, a measure of complexity of neuronal oscillations. Across sessions, both groups showed a modulation of complexity of beta-2 band (20-29Hz) at midfrontal regions, but only MC group showed a modulation of complexity of theta band (3.5-7.5Hz) at posterior regions. Therefore, the neuronal complexity patterns showed different changes in EEG frequency band specific complexity resulting in two different types of interventions. Moreover, the different neural responses to listening to monochords and PMR were observed after regular relaxation interventions over a short time span.

  6. 模拟/数字混合滤波器组的局部子带重构算法设计%Design of Hybrid Filter Banks Using Chebyshev Norm Performance Measure in Reduced Frequency Band

    Institute of Scientific and Technical Information of China (English)

    王玮; 王钊; 杜冰馨

    2016-01-01

    模拟/数字混合滤波器组( HFB)系统可以用于实现超宽带模拟信号的高速高精度采样。针对许多应用场合仅需用HFB系统重构特定频带范围内信号的问题,提出通过最小化系统Chebyshev范数设计有限长脉冲响应数字综合滤波器的优化方法。该方法将HFB误差系统转化为一个等价的有限维多输入多输出线性时不变数字系统;在期望重构的频率范围内,利用广义KYP引理,给出数字系统在Chebyshev范数性能指标下基于线性矩阵不等式描述的凸优化问题。该算法可以重构期望的频率范围内的信号。仿真实验表明,新方法设计的HFB重构信号误差小于传统算法设计系统的重构信号误差。%Hybrid filter bank (HFB) analog-to-digital systems permit wideband,high frequency analog-to-digital conversion.To reconstruct the signal of interest in reduced frequency band using HFB,Chebyshev norm performance measure is presented to design finite impulse response (FIR) digital synthesis filters of HFB.The FIR filters are designed to minimize performance measure of a hybrid error system.This hybrid and multirate problem is cast as a norm optimization problem involving only linear time-invariant,discrete-time system.Using the generalized Kalman-Yakubovich-Popov (KYP) lemma,the problem is reduced to an optimization problem with a linear matrix inequality.Numerical experiments show the proposed approach yields better performance compared to existing techniques.

  7. Research on Clipping Threshold SAMP Algorithm Based on High Frequency Sub-band Wavelet Transform%小波高频子带变换裁剪阈值SAMP算法研究

    Institute of Scientific and Technical Information of China (English)

    周飞飞; 李雷

    2014-01-01

    文中首先针对离散小波变换( DWT)破坏了低频逼近系数之间的相关性,导致重构质量变差的问题,提出小波高频子带变换( HFSBWT)的稀疏表示方法。其次针对稀疏度自适应匹配追踪( SAMP)算法的原子候选集在每次迭代时成倍增加造成存储空间浪费和重构时间变长等问题,提出裁剪阈值稀疏度自适应匹配追踪( CTSAMP)算法。最后仿真结果表明:对于同一重构算法,小波高频子带变换的图像重构峰值信噪比提高3 dB左右。在小波高频子带变换稀疏表示后采用裁剪阈值稀疏度自适应匹配追踪算法,重构图像的性能有了明显的提高,重构时间缩短一半。%Firstly,aiming at the problem which the Discrete Wavelet Transform ( DWT) destroyed the correlation between low-frequency approximation coefficients,resulting in the bad quality of reconstruction,put forward a new way of sparse representation named High Fre-quency Sub-Band Wavelet Transform ( HFSBWT) . Secondly,in view of the problem that Sparsity Adaptive Matching Pursuit ( SAMP) algorithm atoms candidate set multiplied lead to wasting storage space and lengthening reconstruction time at each iteration,propose a method named Clipping Threshold Sparsity Adaptive Matching Pursuit ( CTSAMP) algorithms. The simulation results show that for the same reconstruction algorithm,the image reconstruction PSNR of HFSBWT increases about 3 dB. For image signal sparse representation use HFSBWT after CTSAMP reconstruction algorithm,the reconstructed performance of image has been significantly improved,and re-construction time has cut in half.

  8. BETA-S, Multi-Group Beta-Ray Spectra

    International Nuclear Information System (INIS)

    1 - Description of program or function: BETA-S calculates beta-decay source terms and energy spectra in multigroup format for time-dependent radionuclide inventories of actinides, fission products, and activation products. Multigroup spectra may be calculated in any arbitrary energy-group structure. The code also calculates the total beta energy release rate from the sum of the average beta-ray energies as determined from the spectral distributions. BETA-S also provides users with an option to determine principal beta-decaying radionuclides contributing to each energy group. The CCC-545/SCALE 4.3 (or SCALE4.2) code system must be installed on the computer before installing BETA-S, which requires the SCALE subroutine library and nuclide-inventory generation from the ORIGEN-S code. 2 - Methods:Well-established models for beta-energy distributions are used to explicitly represent allowed, and 1., 2. - and 3. -forbidden transition types. Forbidden non-unique transitions are assumed to have a spectral shape of allowed transitions. The multigroup energy spectra are calculated by numerically integrating the energy distribution functions using an adaptive Simpson's Rule algorithm. Nuclide inventories are obtained from a binary interface produced by the ORIGEN-S code. BETA-S calculates the spectra for all isotopes on the binary interface that have associated beta-decay transition data in the ENSDF-95 library, developed for the BETA-S code. This library was generated from ENSDF data and contains 715 materials, representing approximately 8500 individual beta transition branches. 3 - Restrictions on the complexity of the problem: The algorithms do not treat positron decay transitions or internal conversion electrons. The neglect of positron transitions in inconsequential for most applications involving aggregate fission products, since most of the decay modes are via electrons. The neglect of internal conversion electrons may impact on the accuracy of the spectrum in the low

  9. S-band active array filtenna with enhanced X-band spurious interference suppression

    NARCIS (Netherlands)

    Cifola, L.; Gerini, G.; Berg, S. van den; Water, F. van de

    2014-01-01

    In the present work, the design of an S-band active array antenna with inherent frequency selectivity properties is described. The radiating element, based on a stacked-patch configuration, is characterized by an operational bandwidth of [2.8-3.4] GHz. In-band frequency selectivity is performed by a

  10. Hydrolyses of alpha-naphthyl acetate, beta-naphthyl acetate, and acetyl-DL-phenylalanine beta-naphthyl ester

    DEFF Research Database (Denmark)

    Kirkeby, S; Moe, D

    1983-01-01

    Using simultaneous coupling azo dye techniques kidney enzymes active against alpha-naphthyl acetate, beta-naphthyl acetate, and acetyl-DL-phenylalanine beta-naphthyl ester are characterized. The enzymes show identical distribution in the section. The banding patterns in zymograms are the same after...

  11. Anthelmintic resistance in Swedish sheep flocks based on a comparison of the results from the faecal egg count reduction test and resistant allele frequencies of the beta-tubulin gene.

    Science.gov (United States)

    Höglund, Johan; Gustafsson, Katarina; Ljungström, Britt-Louise; Engström, Annie; Donnan, Alison; Skuce, Philip

    2009-04-01

    A faecal egg count reduction test (FECRT) survey was conducted during the grazing season 2006 and 2007 to provide an updated indication of the prevalence of anthelmintic resistance in sheep flocks in Sweden. A total of 1330 faecal samples from 90 flocks on 45 farms, with a minimum of 20 ewes each, was collected by local sheep veterinarians. Per treatment group, approximately 15 lambs were dewormed either with oral suspensions of ivermectin (Ivomec vet.) or albendazole (Valbazen vet.). The efficacy on each farm was investigated either in 2006 or 2007 by faecal egg counts collected on the day of treatment and in a new sample from the same animals 7-10 days later. Third-stage larvae (L3) were initially identified morphologically from pooled cultures. These were then used as the source of genomic DNA template for two molecular tests. The first was a PCR-based test for specific identification of Haemonchus contortus, and the second was a Pyrosequencing assay for the analysis of benzimidazole (BZ) resistance targeting the P200 mutation in the parasite's beta-tubulin gene. Larval cultures indicated that Teladorsagia and Trichostrongylus were the predominant genera, but Haemonchus was diagnosed in 37% of the flocks. The PCR results revealed an almost 100% agreement with those farms that had previously been shown to have Haemonchus present, even when the % prevalence was low (approximately 3%). Only two (4%) of the surveyed farms showed evidence of BZ-resistant worm populations, with H. contortus being the species implicated according to post-treatment larval culture results. The Pyrosequencing assay detected BZ resistant allele frequencies of >40% in the Haemonchus-positive farms and 100% resistant alleles in the clinically most resistant farms. These preliminary results suggest that the FECRT is less sensitive than the molecular test at detecting BZ resistance. However, both tests need to be interpreted carefully, bearing in mind the relative proportions of species

  12. 一款共面可覆盖 WLAN 及 WiMAX 频段的三频笔记本电脑天线的设计%Design of a Tri-band Coplanar Notebook Antenna for WLAN/WiMAX Frequency Bands Application

    Institute of Scientific and Technical Information of China (English)

    栗建豪; 吴多龙; 吴艳杰; 黎宇彪

    2014-01-01

    Using simulation and experiment methods , a compact , coplanar , and cover all the operating bands of 2.4/5.2/5.8/GHz WLAN and 2.5/3.5/5.5 GHz WiMAX systems of laptop antenna were de-signed .The antenna adopts coupling feed mode , by adjusting the size of the rectangular radiating surface and L-typed structure, and the dimension of the slot-coupling to arouse the resonant frequency of 2.5GHz and 5.5GHz; through cutting a U-shaped slit in the L-type radiation surface to achieve the resonance point of 3.5GHz, the length of the U-shaped is 1/4λat the resonance point of about 4GHz.The antenna shows an entire area is only 7.5 mm ×17.5 mm ( not including the system ground plane ) .In the proce-dure of design , through changing the gaps between the rectangular and L-shaped radiator can adjust the strength of the resonance point , but also realize the matching of input and output impedance .When mounted at the top edge of the display panel in the laptops , three wide operating bands for covering all the desired operating bands of WLAN/WiMAX systems are obtained and the antenna has a good radiation characteristics .The optimizations by using the simulator software Ansoft HFSS were performed , and an actual model has been prototyped for experimental measurements , the measured and simulated results are in good agreement .%采用软件设计和实验相结合的方法,设计了一款紧凑型、共平面、能覆盖2.4/5.2/5.8 GHz WLAN和2.5/3.5/5.5 GHz WiMAX工作频段的笔记本电脑天线.该天线采用耦合馈电方式,通过调节矩形辐射面和L形结构尺寸以及耦合缝隙的大小来产生2.5 GHz和5.5 GHz的谐振频率;通过在L形辐射表面开一个U形缝隙来实现3.5 GHz处的谐振点,该U形槽的长度大约为4 GHz谐振点处的1/4 l;其整个天线的面积只有7.5 mm ×17.5 mm(不包括笔记本电脑天线的地板).在设计中通过调节矩形耦合辐射体与L形辐射面的间距可以有效地调节各谐振

  13. Cross-frequency coupling of brain oscillations: an impact of state anxiety.

    Science.gov (United States)

    Knyazev, Gennady G

    2011-06-01

    In recent studies, statistical relations among activities in different frequency EEG bands have been reported. Most of these studies investigate within-subject cross-frequency relations, such as amplitude-amplitude, phase-amplitude and phase-phase coupling between different frequencies. All these cross-frequency interactions are considered to be transient correlates of information processing. However, some authors suggested that a particular pattern of amplitude-amplitude relations among different frequencies may be associated with relatively stable states or even traits. Particularly delta-beta amplitude-amplitude correlation measured in the between-subject domain was shown to lawfully increase in some presumably anxiogenic conditions and in some pathological groups. The main purpose of this paper was to further explore the phenomenon of between-subject delta-beta correlation in terms of its spatial localization, relatedness to state anxiety, and similarity to within-subject amplitude-to-amplitude and phase-to-amplitude coupling. Independent component analysis was used to identify temporally correlated spatial patterns that most reliably show the phenomenon of between-subject delta-beta correlation. Results of this analysis show that in an anxiogenic situation, delta-beta correlation increases in a network of cortical areas which includes the orbitofrontal and the anterior cingulate cortices as its main node. This increase of correlation is accompanied by an increase of delta power and connectivity in the same cortical regions. Analysis of the within-subject delta-beta amplitude-to-amplitude and phase-to-amplitude coupling showed that in an anxiogenic situation, in subjects with higher scores on state anxiety they also tend to increase in the same set of cortical areas. PMID:21458502

  14. Monolithically integrated absolute frequency comb laser system

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Michael C.

    2016-07-12

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

  15. 非理想NNC-DFH接收机抗部分频带干扰性能分析%Performance analysis of non-ideal noise-normalization combining differential frequency hopping receiver in partial-band jamming

    Institute of Scientific and Technical Information of China (English)

    屈晓旭; 娄景艺; 高俊

    2012-01-01

    为改善差分跳频系统的抗部分频带干扰性能,提出一种噪声归一化合并差分跳频接收机模型.采用矩生成函数法推导了非理想噪声功率估计条件下系统误符号率的联合上界.将信道建模为瑞利衰落信道,同时考虑了加性背景热噪声的影响.数值和仿真结果验证了理论分析的正确性.研究结果表明:在噪声估计不存在严重偏差时(估计误差因子满足0.1<λ<3.0),噪声归一化合并差分跳频接收机在最坏部分频带干扰下的性能优于乘积合并和线性合并差分跳频接收机,且当噪声估计值略低于理想估计值时(0.2<λ<0.6),系统误符号性能优于理想噪声估计条件下的误符号性能.%A differential frequency hopping (DFH) receiver utilizing noise-normalization combining (NNC) was proposed to improve its performance of rejecting partial-band noise jamming (PBNJ). Symbol error rate (SER) upper bound of this receiver under PBNJ was analyzed using moment generating function method with non-ideal noise power estimation considered. DFH signal was assumed Rayleigh faded and corrupted by additive background thermal noise. The theoretical analysis was validated by the numerical and simulation results. It is shown that when the noise power estimation error is not great ( 0. 1 <λ A < 3. 0 , λis the estimation error factor) , NNC-DFH receiver is superior to the product combining DFH receiver and the linear combing DFH receiver when they are jammed by the worst-case PBNJ. System with noise power a little lower estimated (0. 2 < λ < 0. 6) outperforms that with ideal noise power estimation.

  16. 曲面双层带通频率选择表面天线罩设计%Design of a Curved Radome with Double-layer Band-pass Frequency Selective Surface

    Institute of Scientific and Technical Information of China (English)

    陈毅乔

    2016-01-01

    For the problem that the complex curved profile seriously affects the transmission properties of frequency selective surface( FSS) radome,a design method based on path tracing technique is proposed. First,the method uses plane mesh to fit and characterize the curved surface. Then,it uses the path tracing algorithm to calculate the arrangement of FSS. Finally,the plane FSS structure is projected on the curved surface. So the arrangement and modeling of curved FSS are more accurate. The design method is applied to design aK band A-sandwich curved FSS radome,and the fabricated radome is tested and verified. The results indicate that the transmission properties of the curved FSS radome agree well with those of the plane structure,and the antenna radiation pattern is less affected,so the effect of the complex curved profile is e-liminated effectively.%针对复杂曲面外形严重影响频率选择表面( FSS)天线罩传输特性的问题,提出了一种基于表面寻迹技术的曲面FSS天线罩设计方法。首先通过平面网格剖分对曲面进行拟合及表征,然后采用表面寻迹算法对FSS阵列的排布位置进行计算,最后将平面FSS结构投影于曲面外形,从而提高了曲面FSS阵列的排布及建模精度。采用该方法完成了某K频段A夹层曲面FSS天线罩的设计及测试,结果表明该曲面FSS罩的传输特性与平面FSS基本一致,且对天线辐射方向图影响较小,有效消除了复杂曲面外形对天线罩传输特性的影响。

  17. 一种L/S波段双频双圆极化缝隙天线的设计实现%Design and Implementation Circularly Polarized Slot of Dual-Frequency Dual Antenna for L/S Band

    Institute of Scientific and Technical Information of China (English)

    吴锟; 屈德新; 胡永金

    2012-01-01

    文章设计了一种用于实现L波段圆极化的平面缝隙天线,并在此天线的基础上,通过添加寄生贴片,实现L/S波段双频双圆极化的性能。该天线通过一条矩形缝隙将圆环形天线切断,调节缝隙的宽度和角度,实现了圆极化辐射,通过背面的矩形条带对天线激励,使得天线的阻抗得以较好地匹配。在此基础上,又在天线上方加一圆形寄生贴片,通过互耦作用,分别实现了在1.39GHz-1.48GHz和2.60GHz-2.66GHz两个频段不同旋向的圆极化辐射,同时将矩形条带馈线调整为十字形,改善了阻抗带宽。借助于仿真软件对天线参数进行优化,并在此基础上制作了实物。测试结果表明,该设计达到了仿真的效果。%A dual-frequency circularly polarized slot antenna for L-band was designed. Based on this, the proposed antenna realizes dual circularly polarized radiations at L/S by loading a par- asitic patch. The antenna is composed of an annular with a rectangular slot. By adjusting the size and the angle of the slot, the circular polarization was achieved. The bandwidth matches well with the rectangular feed-line. And then a circular parasitic patch was put above the antenna. As the mutual-coupling of the two patches, the proposed antenna realizes dual circularly polarized radiations at 1.39-1.48 GHz and 2.60-2. 66 GHz. For designing the cross feeding strip, the impedance bandwidth is better. The parameters of the antenna were optimized by the simulation software, and the antenna was manufactured. The measure result meets the simulation.

  18. Correlation of β-band with ground state band in medium mass nuclei

    International Nuclear Information System (INIS)

    The low energy levels of even Z even N nuclei in medium mass region A = 150-200 away from closed shells develop collective characteristics. The lowest levels can be grouped into three K-bands. The lowest one based on the ground state forms the ground state rotational band. The rotational band, based on the axially symmetric vibration of the nuclear core with K= 02 is called the beta vibrational band. The one based on the axially asymmetric vibration of the nuclear core with K=2 projection on the symmetry axis is called the K=2, γ-vibrational band. There is interest in the nature of the K= 02 band. This is called the geometric view of the Bohr Mottelson unified collective model

  19. 47 CFR 90.1213 - Band plan.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. The following channel center frequencies are permitted to be aggregated...

  20. Ultrafast Narrow Band Modulation of VCSELs

    Science.gov (United States)

    Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Multimode beating was greatly enhanced by taking output from part (e.g., half) of the output facet. Simpler sources of microwaves and millimeter waves of various frequencies were generated by varying the VCSEL diameter in a single multimode VCSEL our coupling of a few VCSELs. Breathing frequency in multi-mode operations affects modulation response and bandwidth. Optimizing RO frequency and mode beating frequency could potentially expand bandwidths suitable for wide band digital communications.

  1. Aesthetic appreciation: from time-frequency analysis to synchronization

    Directory of Open Access Journals (Sweden)

    Enric eMunar

    2012-01-01

    Full Text Available Improvements in neuroimaging methods have afforded significant advances in our knowledge of the cognitive and neural foundations of aesthetic appreciation. We used magnetoencephalography (MEG to register brain activity during an aesthetic appreciation task. The data were analyzed with Event-Related Field (ERF and Time-Frequency (TF procedures. ERFs revealed no significant differences between brain activity related with stimuli rated as beautiful and not-beautiful. TF analysis showed clear differences between both conditions 400 ms after stimulus onset. In the four frequency bands (theta, alpha, beta and gamma oscillatory power was significantly greater for stimuli rated as beautiful than those regarded as not-beautiful. These results are interpreted in the frame of synchronization studies.

  2. Band-selective radiofrequency pulses

    Science.gov (United States)

    Geen, Helen; Freeman, Ray

    A theoretical treatment is given of the general problem of designing amplitude-modulated radiofrequency pulses that will excite a specified band of frequencies within a high-resolution NMR spectrum with uniform intensity and phase but with negligible excitation elsewhere. First a trial pulse envelope is defined in terms of a finite Fourier series and its frequency-domain profile calculated through the Bloch equations. The result is compared with the desired target profile to give a multidimensional error surface. The method of simulated annealing is then used to find the global minimum on this surface and the result refined by standard gradient-descent optimization. In this manner, a family of new shaped radio-frequency pulses, known as BURP ( band-selective, uniform response, pure-phase) pulses, has been created. These are of two classes—pulses that excite or invert z magnetization and those that act as general-rotation πr/2 or π pulses irrespective of the initial condition of the nuclear magnetization. It was found convenient to design the latter class as amplitude-modulated time-symmetric pulses. Tables of Fourier coefficients and pulse-shape ordinates are given for practical implementation of BURP pulses, together with the calculated frequency-domain responses and experimental verifications. Examples of the application of band-selective pulses in conventional and multidimensional spectroscopy are given. Pure-phase pulses of this type should also find applications in magnetic resonance imaging where refocusing schemes are undesirable.

  3. Diet after gastric banding

    Science.gov (United States)

    Gastric banding surgery - your diet; Obesity - diet after banding; Weight loss - diet after banding ... about any problems you are having with your diet, or about other issues related to your surgery ...

  4. Iliotibial band syndrome - aftercare

    Science.gov (United States)

    IT band syndrome - aftercare; Iliotibial band friction syndrome - aftercare ... If you have iliotibial band syndrome you may notice: Mild pain on the outside of your knee when you begin to exercise, which goes ...

  5. Approximating the inverse of banded matrices by banded matrices with applications to probability and statistics

    CERN Document Server

    Bickel, Peter J

    2010-01-01

    In the first part of this paper we give an elementary proof of the fact that if an infinite matrix $A$, which is invertible as a bounded operator on $\\ell^2$, can be uniformly approximated by banded matrices then so can the inverse of $A$. We give explicit formulas for the banded approximations of $A^{-1}$ as well as bounds on their accuracy and speed of convergence in terms of their band-width. In the second part we apply these results to covariance matrices $\\Sigma$ of Gaussian processes and study mixing and beta mixing of processes in terms of properties of $\\Sigma$. Finally, we note some applications of our results to statistics.

  6. 3D hand motion trajectory prediction from EEG mu and beta bandpower.

    Science.gov (United States)

    Korik, A; Sosnik, R; Siddique, N; Coyle, D

    2016-01-01

    A motion trajectory prediction (MTP) - based brain-computer interface (BCI) aims to reconstruct the three-dimensional (3D) trajectory of upper limb movement using electroencephalography (EEG). The most common MTP BCI employs a time series of bandpass-filtered EEG potentials (referred to here as the potential time-series, PTS, model) for reconstructing the trajectory of a 3D limb movement using multiple linear regression. These studies report the best accuracy when a 0.5-2Hz bandpass filter is applied to the EEG. In the present study, we show that spatiotemporal power distribution of theta (4-8Hz), mu (8-12Hz), and beta (12-28Hz) bands are more robust for movement trajectory decoding when the standard PTS approach is replaced with time-varying bandpower values of a specified EEG band, ie, with a bandpower time-series (BTS) model. A comprehensive analysis comprising of three subjects performing pointing movements with the dominant right arm toward six targets is presented. Our results show that the BTS model produces significantly higher MTP accuracy (R~0.45) compared to the standard PTS model (R~0.2). In the case of the BTS model, the highest accuracy was achieved across the three subjects typically in the mu (8-12Hz) and low-beta (12-18Hz) bands. Additionally, we highlight a limitation of the commonly used PTS model and illustrate how this model may be suboptimal for decoding motion trajectory relevant information. Although our results, showing that the mu and beta bands are prominent for MTP, are not in line with other MTP studies, they are consistent with the extensive literature on classical multiclass sensorimotor rhythm-based BCI studies (classification of limbs as opposed to motion trajectory prediction), which report the best accuracy of imagined limb movement classification using power values of mu and beta frequency bands. The methods proposed here provide a positive step toward noninvasive decoding of imagined 3D hand movements for movement-free BCIs

  7. Levered and unlevered Beta

    OpenAIRE

    Fernandez, Pablo

    2003-01-01

    We prove that in a world without leverage cost the relationship between the levered beta ( L) and the unlevered beta ( u) is the No-costs-of-leverage formula: L = u + ( u - d) D (1 - T) / E. We also analyze 6 alternative valuation theories proposed in the literature to estimate the relationship between the levered beta and the unlevered beta (Harris and Pringle (1985), Modigliani and Miller (1963), Damodaran (1994), Myers (1974), Miles and Ezzell (1980), and practitioners) and prove that all ...

  8. The Science Case for ALMA Band 2 and Band 2+3

    CERN Document Server

    Fuller, G A; Beltran, M; Casasola, V; Caselli, P; Cicone, C; Costagliola, F; De Breuck, C; Hunt, L; Jimenez-Serra, I; Laing, R; Longmore, S; Massardi, M; Paladino, R; Ramstedt, S; Richards, A; Testi, L; Vergani, D; Viti, S; Wagg, J

    2016-01-01

    We discuss the science drivers for ALMA Band 2 which spans the frequency range from 67 to 90 GHz. The key science in this frequency range are the study of the deuterated molecules in cold, dense, quiescent gas and the study of redshifted emission from galaxies in CO and other species. However, Band 2 has a range of other applications which are also presented. The science enabled by a single receiver system which would combine ALMA Bands 2 and 3 covering the frequency range 67 to 116 GHz, as well as the possible doubling of the IF bandwidth of ALMA to 16 GHz, are also considered.

  9. Realized Beta GARCH

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger; Voev, Valeri Radkov

    2014-01-01

    as the beta. We apply the model to a large set of assets and find the conditional betas to be far more variable than usually found with rolling-window regressions based exclusively on daily returns. In the empirical part of the paper, we examine the cross-sectional as well as the time variation...... of the conditional beta series during the financial crises....

  10. S-Band propagation measurements

    Science.gov (United States)

    Briskman, Robert D.

    1994-08-01

    A geosynchronous satellite system capable of providing many channels of digital audio radio service (DARS) to mobile platforms within the contiguous United States using S-band radio frequencies is being implemented. The system is designed uniquely to mitigate both multipath fading and outages from physical blockage in the transmission path by use of satellite spatial diversity in combination with radio frequency and time diversity. The system also employs a satellite orbital geometry wherein all mobile platforms in the contiguous United States have elevation angles greater than 20 deg to both of the diversity satellites. Since implementation of the satellite system will require three years, an emulation has been performed using terrestrial facilities in order to allow evaluation of DARS capabilities in advance of satellite system operations. The major objective of the emulation was to prove the feasibility of broadcasting from satellites 30 channels of CD quality programming using S-band frequencies to an automobile equipped with a small disk antenna and to obtain quantitative performance data on S-band propagation in a satellite spatial diversity system.

  11. C-Band All-Sky Survey: A First Look at the Galaxy

    CERN Document Server

    Irfan, M O; Davies, R D; Copley, C; Davis, R J; Ferreira, P G; Holler, C M; Jonas, J L; Jones, Michael E; King, O G; Leahy, J P; Leech, J; Leitch, E M; Muchovej, S J C; Pearson, T J; Peel, M W; Readhead, A C S; Stevenson, M A; Sutton, D; Taylor, Angela C; Zuntz, J

    2015-01-01

    We present an analysis of the diffuse emission at 5 GHz in the first quadrant of the Galactic plane using two months of preliminary intensity data taken with the C-Band All Sky Survey (C-BASS) northern instrument at the Owens Valley Radio Observatory, California. Combining C-BASS maps with ancillary data to make temperature-temperature plots we find synchrotron spectral indices of $\\beta = -2.65 \\pm 0.05$ between 0.408 GHz and 5 GHz and $ \\beta = -2.72 \\pm 0.09$ between 1.420 GHz and 5 GHz for $-10^{\\circ} < |b| < -4^{\\circ}$, $20^{\\circ} < l < 40^{\\circ}$. Through the subtraction of a radio recombination line (RRL) free-free template we determine the synchrotron spectral index in the Galactic plane ($ |b| < 4^{\\circ}$) to be $\\beta = -2.56 \\pm 0.07$ between 0.408 GHz and 5 GHz, with a contribution of $53 \\pm 8$ per cent from free-free emission at 5\\,GHz. These results are consistent with previous low frequency measurements in the Galactic plane. By including C-BASS data in spectral fits we dem...

  12. Frequency dependent thermal expansion in binary viscoelasticcomposites

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, James G.

    2007-12-01

    The effective thermal expansion coefficient beta* of abinary viscoelastic composite is shown to be frequency dependent even ifthe thermal expansion coefficients beta A and beta B of both constituentsare themselves frequency independent. Exact calculations for binaryviscoelastic systems show that beta* is related to constituent valuesbeta A, beta B, volume fractions, and bulk moduli KA, KB, as well as tothe overall bulk modulus K* of the composite system. Then, beta* isdetermined for isotropic systems by first bounding (or measuring) K* andtherefore beta*. For anisotropic systems with hexagonal symmetry, theprincipal values of the thermal expansion beta*perp and beta*para can bedetermined exactly when the constituents form a layered system. In allthe examples studied, it is shown explicitly that the eigenvectors of thethermoviscoelastic system possess non-negative dissipation -- despite thecomplicated analytical behavior of the frequency dependent thermalexpansivities themselves. Methods presented have a variety ofapplications from fluid-fluid mixtures to fluid-solid suspensions, andfrom fluid-saturated porous media to viscoelastic solid-solidcomposites.

  13. Warm-Up Activities of Middle and High School Band Directors Participating in State-Level Concert Band Assessments

    Science.gov (United States)

    Ward, Justin P.; Hancock, Carl B.

    2016-01-01

    The purpose of this study was to examine the warm-ups chosen by concert band directors participating in state-level performance assessments. We observed 29 middle and high school bands and coded the frequency and duration of warm-up activities and behaviors. Results indicated that most bands rehearsed music and played scales, long tones, and…

  14. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model’s five central predictions: (1) Since constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for U.......S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...... of the BAB factor is low; (4) Increased funding liquidity risk compresses betas toward one; (5) More constrained investors hold riskier assets....

  15. Betting against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    2014-01-01

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically...... for US equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures. (2) A betting against beta (BAB) factor, which is long leveraged low-beta assets and short high-beta assets, produces significant positive risk-adjusted returns. (3) When funding constraints tighten......, the return of the BAB factor is low. (4) Increased funding liquidity risk compresses betas toward one. (5) More constrained investors hold riskier assets....

  16. Roughing up Beta

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor

    Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross......-section of expected returns. Based on a novel highfrequency dataset of almost one-thousand individual stocks over two decades, we find that the two rough betas associated with intraday discontinuous and overnight returns entail significant risk premiums, while the intraday continuous beta is not priced in the cross......-section. An investment strategy that goes long stocks with high jump betas and short stocks with low jump betas produces significant average excess returns. These higher risk premiums for the discontinuous and overnight market betas remain significant after controlling for a long list of other firm characteristics...

  17. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  18. All-solid-state cw frequency-doubling Nd:YLiF4/LBO blue laser with 4.33 W output power at 454 nm under in-band diode pumping at 880 nm.

    Science.gov (United States)

    Lü, Yanfei; Zhang, Xihe; Cheng, Weibo; Xia, Jing

    2010-07-20

    We generated efficient blue laser output at 454 nm by intracavity frequency doubling of a continuous-wave (cw) diode-pumped Nd:YLiF(4) (Nd:YLF) laser at 908 nm based on the (4)F(3/2)-(4)I(9/2) transition. With 32.8 W of incident pump power at 880 nm and the frequency-doubling crystal LiB(3)O(5), a level as high as 4.33 W of cw output power at 454 nm is achieved, corresponding to an optical conversion efficiency of 13.2% with respect to the incident pump power. To the best of our knowledge, this is the first blue laser at 454 nm generated by intracavity frequency doubling of a diode-pumped Nd:YLF. PMID:20648194

  19. Exploiting the Terahertz Band for Radionavigation

    Science.gov (United States)

    Parker, John Scott; Mickelson, Pascal; Yeak, Jeremy; Kremeyer, Kevin; Rife, Jason

    2016-10-01

    This paper demonstrates the feasibility of GPS-like ranging at terahertz (THz) frequencies. It is well established that GPS carrier signals are vulnerable to jamming via radio-frequency interference (RFI). As a result, there is a need for alternative radionavigation systems. THz signals offer a compelling option. Because of their high frequency (roughly ×100 higher than GPS), THz signals can be used to make highly precise range measurements. In addition, the large separation between the GPS and THz frequencies means that interference at GPS frequencies is very unlikely to impact the THz band. This paper lays the groundwork for a GPS-like ranging capability at THz frequencies. To this end, we identify key differences between THz hardware and GPS (radio frequency) hardware; we experimentally evaluate performance of a 0.30-THz system on a compact outdoor test range, and we introduce a measurement error model that highlights the distinctive role that multipath interference plays at THz frequencies.

  20. Multiple band circularly polarized microstrip antenna

    Science.gov (United States)

    Yu, I. P. (Inventor)

    1980-01-01

    A multiple antenna assembly for communicating electromagnetic radiation is disclosed. An antenna element stack is constructed of a plurality of elliptical lamina antenna elements mutally separated by layers of dielectric material, and separated from a ground plane by dielectric material. The antenna assembly is coupled through a feed line in contact with the top antenna element. A conductor joins the remaining antenna elements to the ground plane. Each individual antenna element is operable for communication reception and transmission within a frequency band determined by the size of the particular antenna element. The sizes of the antenna elements may be selected to provide electromagnetic radiation communication over several distinct frequency bands, or to connect the individual bands into a broad band.

  1. RESEARCH OF BJMOSFET FREQUENCY CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    Zeng Yun; Yang Hongguan; Shang Yuquan; Li Xiaolei; Zhang Yan; Wu Yonghui

    2006-01-01

    The parasitic capacitance effect and its influence to the performance have been investigated in Bipolar Junction Metal-Oxide-Semiconductor Field-Effect Transistor (BJMOSFET). The frequency characteristic equivalent circuit and high frequency response model of BJMOSFET have been presented. The frequency characteristic of BJMOSFET is simulated using the multi-transient analytical method and PSPICE9 simulator.The conclusions that BJMOSFET owns less total capacitance, wider frequency band, better transient characteristic and better frequency responses are reached by comparing with the traditional MOSFET at the same structure parameters and bias conditions. BJMOSFET, as a novel promising high frequency device, would be desired to find application in future integrated circuit.

  2. Compact multi-band novel-shaped planar monopole antenna for DCS, Bluetooth, and ultra-wide-band applications

    OpenAIRE

    Vijay K. Sambhe; Rahul N. Awale; Abhay Wagh

    2016-01-01

    In this study, simple and compact novel-shape planar monopole antenna for multi-band operation such as DCS, Bluetooth, and ultra-wide-band (UWB) is proposed. Proposed antenna comprises of circular ring with extended rectangular monopole antenna in one of the arm of the circular ring and inverted L-shape monopole antenna at the centre of the structure is placed to generate multiple resonances at different frequencies. In this structure, Bluetooth frequency band generates due to extended rectan...

  3. Design and Simulation of Edge-Coupled Stripline Band Pass Filter for U band

    Directory of Open Access Journals (Sweden)

    Pawan Shakdwipee

    2013-08-01

    Full Text Available In this paper, a band pass filter structure using Ansoft designer software and Matlab software simulation tool are presented. The filter is operated at U Band range in higher order 50 GHz edge-coupled Stripline band pass filter for different microwave application. For the proposed work we consider simulation using Roger R03203 substrate with dielectric constant of 3.02, Conductor Thickness 0.035 mm and Substrate Height 0.787 mm. This filter is design at a center frequency of 50 GHz with 8 GHz bandwidth. Simulation results show that the filter operation is optimum and best in this range and results show good performance and agree well with the high frequency EM full wave simulation. In this paper, band pass filter development with the assistance of the Richards-Kuroda Transformation method, is used. Moreover, measured S parameters denote the center frequency is also strongly influenced by the variation of Roger's material's dielectric constants. By analyzing the characteristics at center frequency of the filter, both theoretical and simulated data are accumulated for broadening application filed. The band pass filter exhibits advantages of small size and high reliability compared to conventional planar filter structure, which makes the band pass filter suitable for U Band communicational application. This filter shows attractive characteristics for BPF applications.

  4. Dual-band Omnidirectional Circularly Polarized Antenna

    OpenAIRE

    Narbudowicz, Adam; Bao, Xiulong; Ammann, Max

    2013-01-01

    A dual-band omnidirectional circularly polarized antenna is proposed. The antenna comprises back-to-back microstrip patches fed by a coplanar waveguide. A very low frequency ratio of 1.182 has been achieved, which can be easily tuned by adjusting four lumped capacitors incorporated into the antenna. An analysis of the omnidirectional circular polarization mechanism as well the dual band operation is provided and confirmed by numerical and experimental data. Key parameters to tune the resonant...

  5. Band parameters of phosphorene

    DEFF Research Database (Denmark)

    Lew Yan Voon, L. C.; Wang, J.; Zhang, Y.;

    2015-01-01

    Phosphorene is a two-dimensional nanomaterial with a direct band-gap at the Brillouin zone center. In this paper, we present a recently derived effective-mass theory of the band structure in the presence of strain and electric field, based upon group theory. Band parameters for this theory are co...

  6. Flat Band Quastiperiodic Lattices

    Science.gov (United States)

    Bodyfelt, Joshua; Flach, Sergej; Danieli, Carlo

    2014-03-01

    Translationally invariant lattices with flat bands (FB) in their band structure possess irreducible compact localized flat band states, which can be understood through local rotation to a Fano structure. We present extension of these quasi-1D FB structures under incommensurate lattices, reporting on the FB effects to the Metal-Insulator Transition.

  7. Cloning of a short HLA-DQ beta locus-specific cDNA probe: typing for DQw specificities.

    Science.gov (United States)

    Sood, S K; McCusker, C T; Singal, D P

    1989-01-01

    A short HLA-DQ beta locus-specific (141 bp) probe was cloned from the full-length pII-beta-1 cDNA. Pst 1-digested genomic DNA from homozygous typing cell lines (HTC) was hybridized with this short DQ beta locus-specific, pDQ beta 141, probe. Restriction fragment length polymorphism (RFLP) patterns generated with this DQ beta locus-specific probe were compared with those obtained with the full-length (627 bp) DQ beta, pII-beta-1, probe. The results demonstrate that the RFLP patterns with the pDQ beta 141 probe were very simple, and no crossreacting DR beta and DX beta bands were observed. DQw1, 2, 3 and 4 specificities could each be identified by a single RFLP. PMID:2467193

  8. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    -looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...

  9. One-Dimensional Anisotropic Band Gap Structure

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The band gap structure of one-dimensional anisotropic photonic crystal has been studied by means of the transfer matrix formalism. From the analytic expressions and numeric calculations we see some general characteristics of the band gap structure of anisotropic photonic crystals, each band separates into two branches and the two branches react to polarization sensitively. In the practical case of oblique incidence, gaps move towards high frequency when the angle of incidence increases. Under some special conditions, the two branches become degenerate again.

  10. The Novel Microwave Stop-Band Filter

    OpenAIRE

    Chernobrovkin, R. E.; Ivanchenko, I. V.; Korolev, A. M.; Popenko, N. A.; K. Yu. Sirenko

    2008-01-01

    The stop-band filter with the new band-rejection element is proposed. The element is a coaxial waveguide with the slot in the centre conductor. In the frame of this research, the numerical and experimental investigations of the amplitude-frequency characteristics of the filter are carried out. It is noted that according to the slot parameters the two typical resonances (half-wave and quarter-wave) can be excited. The rejection band of the single element is defined by the width, depth, and die...

  11. 大鼠肌紧张带重复低频电刺激后的生物力学及病理学改变%Biomechanical and pathological changes of taut bands in rats after repeated low-frequency electrical stimulation

    Institute of Scientific and Technical Information of China (English)

    王永慧; 孟菲; 丁欣利; 范真真; 王超; 岳寿伟

    2015-01-01

    Objective To investigate the biomechanical and pathological changes in vivo in the taut bands (TB) of biceps femoris in rats after repeated low-frequency electrical stimulation.Methods Twenty-eight Wistar rats were randomly divided into a control group,an electrical intensity-dependent fatigue group,which were subject to electric intensity-dependent fatigue test,and an electrical frequency-dependent fatigue group,which were subject to electrical frequency-dependent fatigue test.After fatigue tests,the taut band of the biceps femoris and the non-taut band of the contralateral biceps femoris were harvested for pathological observation.The maximum contraction force (MCF),electrical intensity-and frequency-dependent fatigue characteristics and any pathological changes in the TBs were assessed and compared to the non-taut band region of the other biceps femoris.Results The MCF at the 15th and 20th stimulation (1.42 ± 0.28 g and 0.93 ± 0.54 g respectively) were significantly lower than that at the 1 st and 5th stimulation of the TBs.High stimulation intensity (HSI) at the 15th and 20th stimulation (3.76 ± 0.71 V and 3.44 ± 0.97 V) were also significantly lower than at the 1st TB stimulation.At the 10th,15th and 20th stimulation of the TBs,MCF and HSI were both significantly lower than in the bands which were not tight.In the frequency-dependent fatigue stimulation tests,the frequency which generated the MCF of the TBs was significantly lower than in the bands which were not tight,while the MCF of the TBs was significantly higher than that of non-TBs.After either intensity or frequency fatigue testing,more severe edema,uneven cytoplasmic death and degeneration of muscle fibers were observed in sections from TBs than from the bands which were not tight.Conclusions Taut muscle bands are significantly less fatigue-resistant than normal muscle fibers.Taut bands may contribute to the fatigue of myofascial pain syndromes.%目的 研究大鼠肌紧张带(TB)重复低频电

  12. Microstrip Antenna for X and Ku Band

    Directory of Open Access Journals (Sweden)

    Sarthak Singhal

    2012-06-01

    Full Text Available A design of microstrip patch antenna gap coupled with two parasitic elements on its non-radiating edges and a single parasitic element on its radiating edge for the operation in X band and Ku band is proposed here. The parasitic elements are partially shorted. This design is giving an impedance bandwidth of 4.967GHz. This antenna is operating over a frequency range of 11.2334 to 16.0431 GHz with centre frequency at 14.3 GHz. The design is simulated by using the MOM based IE3D software.

  13. 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..

  14. Too many betas do not spoil the broth: The role of beta brain oscillations in language processing

    Directory of Open Access Journals (Sweden)

    Sabine eWeiss

    2012-06-01

    Full Text Available Over the past 20 years, brain oscillations have proven to be a gateway to the understanding of cognitive processes. It has been shown that different neurocognitive aspects of language processing are associated with brain oscillations at various frequencies. Frequencies in the beta range (13-30 Hz turned out to be particularly important with respect to cognitive and linguistic manipulations during language processing. Beta activity has been involved in higher-order linguistic functions such as the discrimination of word categories and the retrieval of action semantics as well as semantic memory, and syntactic binding processes, which support meaning construction during sentence processing. From a neurophysiological point of view, the important role of the beta frequencies for such a complex cognitive task as language processing seems reasonable. Experimental evidence suggests that frequencies in the beta range are ideal for maintaining and preserving the activity of neuronal assemblies over time. In particular, recent computational and experimental evidence suggest that beta frequencies are important for linking past and present input and the detection of novelty of stimuli, which are essential processes for language perception as well as production. In addition, the beta frequency’s role in the formation of cell assemblies underlying short-term memory seems indispensable for language analysis. Probably the most important point is the well-known relation of beta oscillations with motor processes. It can be speculated that beta activities reflect the close relationship between language comprehension and motor functions, which is one of the core claims of current theories on embodied cognition.In this article, the importance of beta oscillations for language processing is reviewed based both on findings in psychophysiological and neurophysiological literature.

  15. Variations in the Produce-Associated Microbiota and the Occurrence Frequency of Extended-Spectrum Beta-Lactamase Gram-Negative Bacteria Result in Different Level of Ingestion Risks

    KAUST Repository

    Bokhari, Osama

    2016-04-01

    A monitoring effort that spanned across one and a half years was conducted to examine three types of produce-associated microbiota. Produce type was determined to be the predominant factor affecting the microbial communities. Other significant factors that resulted in differences in the microbial populations were the origin and sampling date. Specifically, produce-associated microbiota among lettuce and tomatoes clustered based on the sampling period. Through molecular and cultivation-based approaches, sporadic presence of extended spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae and Acinetobacter baumannii was detected on lettuce and cucumbers during certain periods of sampling. Quantitative microbial risk assessment denoted varying levels of ingestion risks associated with different types of produce. In particular, the risks arising from ESBL-positive K. pneumoniae in the lettuce were higher than the acceptable annual risk of 10-4. Commonly used approaches to clean and wash the produce were insufficient in removing majority of the produce-associated microbiota. More invasive cleaning approaches or thorough cooking of the produce would be required to mitigate the associated risks. Most of the current reports of ESBL-positive bacterial isolates were identified in nosocomial environment. However, the carriage of such drug-resistant bacteria in food that is consumed daily

  16. Theta, alpha and beta burst transcranial magnetic stimulation: brain modulation in tinnitus

    Directory of Open Access Journals (Sweden)

    Dirk De Ridder, Elsa van der Loo, Karolien Van der Kelen, Tomas Menovsky, Paul van de Heyning, Aage Moller

    2007-01-01

    Full Text Available Introduction: Some forms of tinnitus are considered to be auditory phantom phenomena related to reorganization and hyperactivity of the auditory central nervous system. Repetitive transcranial magnetic stimulation (rTMS is a non-invasive tool capable of modulating human brain activity, using single pulse or burst stimuli. Burst rTMS has only been performed in the theta range, and has not been used clinically. The authors analyze whether burst TMS at theta (5 Hz, alpha (10 Hz and beta (20 Hz frequencies can temporarily suppress narrow band noise/white noise tinnitus, which has been demonstrated to be intractable to tonic stimulation. Methods: rTMS is performed both in tonic and burst mode in 46 patients contralateral to the tinnitus side, at 5, 10 and 20 Hz. Fourteen placebo negative rTMS responders are further analyzed. Results: In 5 patients, maximal tinnitus suppression is obtained with theta, in 2 with alpha and in 7 with beta burst stimulation. Burst rTMS suppresses narrow band/white tinnitus much better than tonic rTMS t(13=6.4, p<.000. Women experience greater suppression of their tinnitus with burst stimulation than men, t(12=2.9, p<.05. Furthermore left sided tinnitus is perceived as more distressing on the TQ than right sided tinnitus, t(12=3.2, p<.01. The lower the tinnitus pitch the more effectively rTMS suppresses tinnitus(r=-0.65, p<0.05. Discussion: Burst rTMS can be used clinically, not only theta burst, but also alpha and beta burst. Burst rTMS is capable of suppressing narrow band/white noise tinnitus very much better than tonic rTMS. This could be due the simple fact that burst neuromodulation is more powerful than tonic neuromodulation or to a differential effect of burst and tonic stimulation on the lemniscal and extralemniscal auditory system. In some patients only alpha or beta burst rTMS is capable of suppressing tinnitus, and theta burst not. Therefore in future rTMS studies it could be worthwhile not to limit burst

  17. Cross-frequency synchronization connects networks of fast and slow oscillations during visual working memory maintenance

    Science.gov (United States)

    Siebenhühner, Felix; Wang, Sheng H; Palva, J Matias; Palva, Satu

    2016-01-01

    Neuronal activity in sensory and fronto-parietal (FP) areas underlies the representation and attentional control, respectively, of sensory information maintained in visual working memory (VWM). Within these regions, beta/gamma phase-synchronization supports the integration of sensory functions, while synchronization in theta/alpha bands supports the regulation of attentional functions. A key challenge is to understand which mechanisms integrate neuronal processing across these distinct frequencies and thereby the sensory and attentional functions. We investigated whether such integration could be achieved by cross-frequency phase synchrony (CFS). Using concurrent magneto- and electroencephalography, we found that CFS was load-dependently enhanced between theta and alpha–gamma and between alpha and beta-gamma oscillations during VWM maintenance among visual, FP, and dorsal attention (DA) systems. CFS also connected the hubs of within-frequency-synchronized networks and its strength predicted individual VWM capacity. We propose that CFS integrates processing among synchronized neuronal networks from theta to gamma frequencies to link sensory and attentional functions. DOI: http://dx.doi.org/10.7554/eLife.13451.001 PMID:27669146

  18. Psychophysiological reactivity to auditory Binaural Beats stimulation in the alpha and theta EEG brain-wave frequency bands: A randomized, double–blind and placebo–controlled study in human healthy young adult subjects

    OpenAIRE

    Pfaff, Hans Uwe

    2014-01-01

    Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Psicología, Departamento de Psicología Biológica y de la Salud. Fecha de lectura: 25-06-2014 Binaural beats are an acoustical illusion of the perception of a “virtual” third tone, fluctuating (i.e. beating) in its volume evoked by two carrier–sinusoids of same amplitudes, but slightly different frequencies f1 and f2, presented by stereo-headphones. Although this illusion was discovered as early as 1839 ...

  19. Band Interaction between Chiral Doublet Bands

    Institute of Scientific and Technical Information of China (English)

    QI Bin; ZHANG Shuang-Quan; WANG Shou-Yu; MENG Jie

    2010-01-01

    @@ Band interaction between the chiral doublet bands based on πh11/2(×) vh-111/2 configuration is investigated in the particle rotor model with different triaxial deformation γ. The variation of chiral partner states with γvalues is understood qualitatively based on the basic picture of two interaction levels, which is confirmed further by the calculated overlap integral of wave functions at different γ values. It is found that the interaction strengths ofchiral partner states are obvionsly different for odd spins and even ones.

  20. Instability of coupled gravity-inertial-Rossby waves on a {beta}-plane in solar system atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, J.F. [KwaZulu-Natal Univ., Durban (South Africa). Astrophysics and Cosmology Research Unit, School of Mathematical Sciences; Alabama Univ., AL (United States). Dept. of Physics, CSPAR; King' s College, Cambridge (United Kingdom)

    2009-07-01

    This paper provides an analysis of the combined theory of gravity-inertial-Rossby waves on a {beta}-plane in the Boussinesq approximation. The wave equation for the system is fifth order in space and time and demonstrates how gravity-inertial waves on the one hand are coupled to Rossby waves on the other through the combined effects of {beta}-, the stratification characterized by the Vaeisaelae-Brunt frequency N, the Coriolis frequency f at a given latitude, and vertical propagation which permits buoyancy modes to interact with westward propagating Rossby waves. The corresponding dispersion equation shows that the frequency of a westward propagating gravity-inertial wave is reduced by the coupling, whereas the frequency of a Rossby wave is increased. If the coupling is sufficiently strong these two modes coalesce giving rise to an instability. The instability condition translates into a curve of critical latitude {theta}{sub c} versus effective equatorial rotational Mach number M, with the region below this curve exhibiting instability. ''Supersonic'' fast rotators are unstable in a narrow band of latitudes around the equator. For example {theta}{sub c}{proportional_to}12 for Jupiter. On the other hand slow ''subsonic'' rotators (e.g. Mercury, Venus and the Sun's Corona) are unstable at all latitudes except very close to the poles where the {beta}- effect vanishes. ''Transonic'' rotators, such as the Earth and Mars, exhibit instability within latitudes of 34 and 39 , respectively, around the Equator. Similar results pertain to Oceans. In the case of an Earth's Ocean of depth 4km say, purely westward propagating waves are unstable up to 26 about the Equator. The nonlinear evolution of this instability which feeds off rotational energy and gravitational buoyancy may play an important role in atmospheric dynamics. (orig.)

  1. Dichroic Filter for Separating W-Band and Ka-Band

    Science.gov (United States)

    Epp, Larry W.; Durden, Stephen L.; Jamnejad, Vahraz; Long, Ezra M.; Sosnowski, John B.; Higuera, Raymond J.; Chen, Jacqueline C.

    2012-01-01

    The proposed Aerosol/Cloud/Ecosystems (ACEs) mission development would advance cloud profiling radar from that used in CloudSat by adding a 35-GHz (Ka-band) channel to the 94-GHz (W-band) channel used in CloudSat. In order to illuminate a single antenna, and use CloudSat-like quasi-optical transmission lines, a spatial diplexer is needed to add the Ka-band channel. A dichroic filter separates Ka-band from W-band by employing advances in electrical discharge machining (EDM) and mode-matching analysis techniques developed and validated for designing dichroics for the Deep Space Network (DSN), to develop a preliminary design that both met the requirements of frequency separation and mechanical strength. First, a mechanical prototype was built using an approximately 102-micron-diameter EDM process, and tolerances of the hole dimensions, wall thickness, radius, and dichroic filter thickness measured. The prototype validated the manufacturing needed to design a dichroic filter for a higher-frequency usage than previously used in the DSN. The initial design was based on a Ka-band design, but thicker walls are required for mechanical rigidity than one obtains by simply scaling the Ka-band dichroic filter. The resulting trade of hole dimensions for mechanical rigidity (wall thickness) required electrical redesign of the hole dimensions. Updates to existing codes in the linear solver decreased the analysis time using mode-matching, enabling the electrical design to be realized quickly. This work is applicable to missions and instruments that seek to extend W-band cloud profiling measurements to other frequencies. By demonstrating a dichroic filter that passes W-band, but reflects a lower frequency, this opens up the development of instruments that both compare to and enhance CloudSat.

  2. Design of Compact Penta-Band and Hexa-Band Microstrip Antennas

    Science.gov (United States)

    Srivastava, Kunal; Kumar, Ashwani; Kanaujia, Binod K.

    2016-03-01

    This paper presents the design of two multi-band microstrip antennas. The antenna-1 gives Penta-Band and antenna-2 gives Hexa-band in the WLAN band. The frequency bands of the antenna-1 are Bluetooth 2.47 GHz (2.43 GHz-2.54 GHz), WiMax band 3.73 GHz (3.71 GHz-3.77 GHz), WLAN 5.1 GHz (4.99 GHz-5.13 GHz), upper WLAN 6.36 GHz (6.29 GHz-6.43 GHz), C band band 7.42 GHz (7.32 GHz-7.50 GHz) and the antenna-2 are WLAN band 2.6 GHz (2.56 GHz-2.63 GHz), 3.0 GHz (2.94 GHz-3.05 GHz), WiMax band 3.4 GHz (3.34 GHz-3.55 GHz), 4.85 GHz (4.81 GHz-4.92 GHz), WLAN 5.3 GHz (5.27 GHz-5.34 GHz) and upper WLAN 6.88 GHz. Both the antennas are fabricated and their measured results are presented to validate the simulated results. Proposed antennas have compact sizes and good radiation performances.

  3. Pure phase-locking of beta/gamma oscillation contributes to the N30 frontal component of somatosensory evoked potentials

    Directory of Open Access Journals (Sweden)

    Leroy Axelle

    2007-09-01

    Full Text Available Abstract Background Evoked potentials have been proposed to result from phase-locking of electroencephalographic (EEG activities within specific frequency bands. However, the respective contribution of phasic activity and phase resetting of ongoing EEG oscillation remains largely debated. We here applied the EEGlab procedure in order to quantify the contribution of electroencephalographic oscillation in the generation of the frontal N30 component of the somatosensory evoked potentials (SEP triggered by median nerve electrical stimulation at the wrist. Power spectrum and intertrial coherence analysis were performed on EEG recordings in relation to median nerve stimulation. Results The frontal N30 component was accompanied by a significant phase-locking of beta/gamma oscillation (25–35 Hz and to a lesser extent of 80 Hz oscillation. After the selection in each subject of the trials for which the power spectrum amplitude remained unchanged, we found pure phase-locking of beta/gamma oscillation (25–35 Hz peaking about 30 ms after the stimulation. Transition across trials from uniform to normal phase distribution revealed temporal phase reorganization of ongoing 30 Hz EEG oscillations in relation to stimulation. In a proportion of trials, this phase-locking was accompanied by a spectral power increase peaking in the 30 Hz frequency band. This corresponds to the complex situation of 'phase-locking with enhancement' in which the distinction between the contribution of phasic neural event versus EEG phase resetting is hazardous. Conclusion The identification of a pure phase-locking in a large proportion of the SEP trials reinforces the contribution of the oscillatory model for the physiological correlates of the frontal N30. This may imply that ongoing EEG rhythms, such as beta/gamma oscillation, are involved in somatosensory information processing.

  4. A Compact Frequency Reconfigurable Antenna for LTE Mobile Handset Applications

    Directory of Open Access Journals (Sweden)

    Munyong Choi

    2015-01-01

    Full Text Available A compact (8 × 62 × 5 mm3; 2.48 cc frequency reconfigurable antenna that uses electrical switching with PIN diodes is proposed for the low frequency LTE band (699 MHz–862 MHz, high frequency LTE band (2496 MHz–2690 MHz, GSM850/900 bands (824 MHz–960 MHz, and DCS/PCS/WCDMA bands (1710 MHz–2170 MHz. The penta-band PIFA is first designed for GSM850/900/DCS/PCS/WCDMA bands by using two slits and ground pins within a limited antenna volume (8 × 54.6 × 5 mm3; 2.18 cc. The frequency reconfigurable antenna based on this penta-band PIFA is thus proposed to additionally cover all LTE bands. The proposed antenna has two PIN diodes with an optimal location. For State 1 (PIN diode 1: ON state, PIN diode 2: OFF state, the proposed antenna covers the low frequency LTE band, DCS/PCS/WCDMA bands, and high frequency LTE band. For State 2 (PIN diode 1: OFF state, PIN diode 2: ON state, the antenna covers the GSM850/900 bands. Simulated and measured results show that the total efficiency of the proposed antenna was greater than 40% for all operating frequency bands.

  5. Application of AWE to Scattering Analysis of the Double-negative Medium over a Broad Frequency Band%AWE在双负媒质宽频散射分析中的应用

    Institute of Scientific and Technical Information of China (English)

    孙玉新; 陈明生; 吴先良; 杨梅

    2011-01-01

    In this paper, the Asymptotic Waveform Evaluation (AWE) technique is applied to study electromagnetic scattering analysis of Double-NeGative (DNG) medium. The PMCHWT equation of the DNG is deduced based on its constitutive relationship. And the surface currents and Radar Cross Section (RCS) at a single frequency point is computed; In order to achieve high-order derivation work, impedance matrix elements are managed. Then the AWE technique is applied to obtain broadband RCS frequency response of the DNG. A good agreement can be seen between AWE and the exact solution. The computational efficiency is improved significantly.%该文旨在利用渐近波形估计(AWE)技术来研究双负媒质(DNG)的电磁散射特性.文章首先从双负媒质(DNG)的本构关系出发,推导出DNG的PMCHWT方程,从而解出单频率入射波下的电流和雷达散射截面(RCS);通过对阻抗矩阵元素的处理,实现了阻抗元素高阶导数的求解,成功的将AWE技术应用于DNG宽频电磁计算领域.计算实例表明:AWE计算的结果能很好地逼近精确解,同时大大提高了计算效率.

  6. One-man band

    OpenAIRE

    Stillman, R.

    2013-01-01

    This website presents practice-based research related to solo simultaneous instrumental performance ('one-man band'). The site was conceived as a creative and widely accessible platform for music and ideas resulting from one-man band activates carried out between 2008 and 2013. Central to this project is an interest in how one-man band technique informs compositional process, including studio production. Through presentation and analysis of the author’s own creative practice, the site exp...

  7. BAND GAP EFFECTS IN PERIODIC CHAIN WITH LOCAL LINEAR OR NON-LINEAR OSCILLATORS

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard

    2007-01-01

    attached linear oscillators. The stop band is located around the resonant frequency of the local oscillators, and thus a stop band can be created in the lower frequency range. In this paper, wave propagation in one-dimensional infinite periodic chains with attached linear and non-linear local oscillators...... within bands of frequencies called stop bands. Stop bands in structures with periodic or random inclusions are located mainly in the high frequency range, as the wave length has to be comparable with the distance between the alternating parts. Wave attenuation is also possible in structures with locally...

  8. Beta relaxation of nonpolymeric liquids close to the glass transition

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Christensen, Tage Emil; Dyre, Jeppe

    2000-01-01

    Dielectric beta relaxation in a pyridine-toluene solution is studied close to the glass transition. Loss peak frequency and maximum loss both exhibit thermal hysteresis. An annealing-state-independent parameter involving loss and loss peak frequency is identified. This parameter has a simple...

  9. Neutrinoless double beta decay

    Indian Academy of Sciences (India)

    Kai Zuber

    2012-10-01

    The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given.

  10. Beta-carotene

    Science.gov (United States)

    ... chemotherapy for a blood cancer called lymphoblastic leukemia. Mental performance. Some evidence suggests that taking beta-carotene ... One is water-based, and the other is oil-based. Studies show that the water-based version ...

  11. Coupling between intrinsic prefrontal HbO2 and central EEG beta power oscillations in the resting brain.

    Science.gov (United States)

    Pfurtscheller, Gert; Daly, Ian; Bauernfeind, Günther; Müller-Putz, Gernot R

    2012-01-01

    There is increasing interest in the intrinsic activity in the resting brain, especially that of ultraslow and slow oscillations. Using near-infrared spectroscopy (NIRS), electroencephalography (EEG), blood pressure (BP), respiration and heart rate recordings during 5 minutes of rest, combined with cross spectral and sliding cross correlation calculations, we identified a short-lasting coupling (duration [Formula: see text] s) between prefrontal oxyhemoglobin (HbO2) in the frequency band between 0.07 and 0.13 Hz and central EEG alpha and/or beta power oscillations in 8 of the 9 subjects investigated. The HbO2 peaks preceded the EEG band power peaks by 3.7 s in 6 subjects, with moderate or no coupling between BP and HbO2 oscillations. HbO2 and EEG band power oscillations were approximately in phase with BP oscillations in the 2 subjects with an extremely high coupling (squared coherence [Formula: see text]) between BP and HbO2 oscillation. No coupling was identified in one subject. These results indicate that slow precentral (de)oxyhemoglobin concentration oscillations during awake rest can be temporarily coupled with EEG fluctuations in sensorimotor areas and modulate the excitability level in the brains' motor areas, respectively. Therefore, this provides support for the idea that resting state networks fluctuate with frequencies of between 0.01 and 0.1 Hz (Mantini et.al. PNAS 2007).

  12. Coupling between intrinsic prefrontal HbO2 and central EEG beta power oscillations in the resting brain.

    Directory of Open Access Journals (Sweden)

    Gert Pfurtscheller

    Full Text Available There is increasing interest in the intrinsic activity in the resting brain, especially that of ultraslow and slow oscillations. Using near-infrared spectroscopy (NIRS, electroencephalography (EEG, blood pressure (BP, respiration and heart rate recordings during 5 minutes of rest, combined with cross spectral and sliding cross correlation calculations, we identified a short-lasting coupling (duration [Formula: see text] s between prefrontal oxyhemoglobin (HbO2 in the frequency band between 0.07 and 0.13 Hz and central EEG alpha and/or beta power oscillations in 8 of the 9 subjects investigated. The HbO2 peaks preceded the EEG band power peaks by 3.7 s in 6 subjects, with moderate or no coupling between BP and HbO2 oscillations. HbO2 and EEG band power oscillations were approximately in phase with BP oscillations in the 2 subjects with an extremely high coupling (squared coherence [Formula: see text] between BP and HbO2 oscillation. No coupling was identified in one subject. These results indicate that slow precentral (deoxyhemoglobin concentration oscillations during awake rest can be temporarily coupled with EEG fluctuations in sensorimotor areas and modulate the excitability level in the brains' motor areas, respectively. Therefore, this provides support for the idea that resting state networks fluctuate with frequencies of between 0.01 and 0.1 Hz (Mantini et.al. PNAS 2007.

  13. [High beta tokamak research

    International Nuclear Information System (INIS)

    Our activities on High Beta Tokamak Research during the past 20 months of the present grant period can be divided into six areas: reconstruction and modeling of high beta equilibria in HBT; measurement and analysis of MHD instabilities observed in HBT; measurements of impurity transport; diagnostic development on HBT; numerical parameterization of the second stability regime; and conceptual design and assembly of HBT-EP. Each of these is described in some detail in the sections of this progress report

  14. Diagnóstico de Fallas en Máquinas Eléctricas Rotatorias Utilizando la Técnica de Espectros de Frecuencia de Bandas Laterales Fault Diagnosis in Rotating Electrical Machines by Side Bands Frequency Spectra Technique

    Directory of Open Access Journals (Sweden)

    Roberto Flores

    2011-01-01

    Full Text Available En el presente trabajo se muestra y se aplica una metodología para el diagnóstico de fallas en máquinas eléctricas rotatorias utilizando la técnica de espectros de frecuencia de bandas laterales de las corrientes de fase. Se establecen sistemas de prueba de laboratorio para verificar las magnitudes de las bandas originadas por fallas tanto mecánicas como eléctricas. Se muestra una serie de resultados para un grupo motor de corriente directa-generador síncrono de 5 kVA desalineado y de dos motores de inducción de 5 HP tipo jaula de ardilla, uno con holgura en soporte de baleros y otro con barras rotas. Además, se comparan los resultados de los espectros empleando un sensor de corriente convencional contra una bobina de Rogowski, obteniendo resultados adecuados para detectar la presencia de falla en las máquinas.In this article a methodology to diagnose faults in rotating electrical machines is presented. The method uses spectral frequency analysis of the phase currents sidebands. Online systems to verify the magnitude of these frequencies, caused not only by mechanical faults but also electrical faults, are presented. The results of a faulty set formed by a direct current motor plus a synchronous generator of 5 kVA and two squirrel-cage induction motors of 5 HP, one with slacked bearings faults and other with broken rotor bars, are presented. Also, the results of the spectra using a conventional current sensor are compared with those of a Rogowski coil, showing that the results of both sensors are suitable to detect machine faults.

  15. {beta} - amyloid imaging probes

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

  16. Photonic band gap in thin wire metamaterials.

    Science.gov (United States)

    Hock, Kai Meng

    2008-03-01

    We investigate the band structure of a class of photonic crystals made from only thin wires. Using a different method, we demonstrate that a complete photonic band gap is possible for such materials. Band gap materials normally consist of space filling dielectric or metal, whereas thin wires occupy a very small fraction of the volume. We show that this is related to the large increase in scattering at the Brillouin zone boundary. The method we developed brings together the calculation techniques in three different fields. The first is the calculation of scattering from periodic, tilted antennas, which we improve upon. The second is the standard technique for frequency selective surface design. The third is obtained directly from low energy electron diffraction theory. Good agreements with experiments for left handed materials, negative materials, and frequency selective surfaces are demonstrated.

  17. Identical Bands and Alignment in 193,194Tl

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-Tao; YU Shao-Ying; LIU Shu-Xin; LIU Yan-Xin; ZHAO En-Guang

    2004-01-01

    @@ The microscopic mechanism of the identical bands in odd odd nucleus 194Tl and its neighbour odd-A nucleus 193Tl are investigated using the particle-number conserving method with monopole and quadrupole pairing interaction.It is found that the blocking effect plays an important role in the variation of moments of inertia (J(1) and J(2))with rotational frequency for the superdeformed bands and identical bands. The alignment of 194Tl bands with respect to the 193 Tl(1) band used as a reference is also discussed.

  18. Resolution beyond classical limits with spatial frequency heterodyning

    Institute of Scientific and Technical Information of China (English)

    A. Mudassar; A. R. Harvey; A. H. Greenaway; J. D. C. Jones

    2006-01-01

    @@ A technique for coherent imaging based on spatial frequency heterodyning is described. Three images corresponding to three physical measurements are recorded. For the first measurement, a scene is simply illuminated with a coherent beam and for measurements 2 and 3, the scene is projected with cosine and sine fringes, respectively. Due to spatial frequency heterodyning, upper and lower side band information falls in the pass band of the imager. These bands are separated and correct phases and positions are assigned to these bands in the spatial frequency domain. An extension of bandwidth is achieved in the frequency domain and the inverse frequency domain data then give a high resolution coherent image.

  19. Amyloid Beta Peptide Slows Down Sensory-Induced Hippocampal Oscillations

    Directory of Open Access Journals (Sweden)

    Fernando Peña-Ortega

    2012-01-01

    Full Text Available Alzheimer’s disease (AD progresses with a deterioration of hippocampal function that is likely induced by amyloid beta (Aβ oligomers. Hippocampal function is strongly dependent on theta rhythm, and disruptions in this rhythm have been related to the reduction of cognitive performance in AD. Accordingly, both AD patients and AD-transgenic mice show an increase in theta rhythm at rest but a reduction in cognitive-induced theta rhythm. We have previously found that monomers of the short sequence of Aβ (peptide 25–35 reduce sensory-induced theta oscillations. However, considering on the one hand that different Aβ sequences differentially affect hippocampal oscillations and on the other hand that Aβ oligomers seem to be responsible for the cognitive decline observed in AD, here we aimed to explore the effect of Aβ oligomers on sensory-induced theta rhythm. Our results show that intracisternal injection of Aβ1–42 oligomers, which has no significant effect on spontaneous hippocampal activity, disrupts the induction of theta rhythm upon sensory stimulation. Instead of increasing the power in the theta band, the hippocampus of Aβ-treated animals responds to sensory stimulation (tail pinch with an increase in lower frequencies. These findings demonstrate that Aβ alters induced theta rhythm, providing an in vivo model to test for therapeutic approaches to overcome Aβ-induced hippocampal and cognitive dysfunctions.

  20. ZEBRAFISH CHROMOSOME-BANDING

    NARCIS (Netherlands)

    PIJNACKER, LP; FERWERDA, MA

    1995-01-01

    Banding techniques were carried out on metaphase chromosomes of zebrafish (Danio rerio) embryos. The karyotypes with the longest chromosomes consist of 12 metacentrics, 26 submetacentrics, and 12 subtelocentrics (2n = 50). All centromeres are C-band positive. Eight chromosomes have a pericentric C-b

  1. Stretch Band Exercise Program

    Science.gov (United States)

    Skirka, Nicholas; Hume, Donald

    2007-01-01

    This article discusses how to use stretch bands for improving total body fitness and quality of life. A stretch band exercise program offers a versatile and inexpensive option to motivate participants to exercise. The authors suggest practical exercises that can be used in physical education to improve or maintain muscular strength and endurance,…

  2. Crack propagation of Ti alloy via adiabatic shear bands

    International Nuclear Information System (INIS)

    This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids

  3. Crack propagation of Ti alloy via adiabatic shear bands

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, I., E-mail: ivanmendozabravo@gmail.com [Instituto Tecnológico de Veracruz (Mexico); Villalobos, D. [Instituto Tecnológico de Veracruz (Mexico); Alexandrov, B.T. [The Ohio State University (United States)

    2015-10-01

    This study was focused on the characterization of the origin and mechanism of crack propagation as a result of hot induction bending of Ti alloy. Plates of Ti–6Al–4V alloy with 12.5 mm of thickness were submitted to hot induction bending below the beta transus temperature. Optical and scanning electron microscopy analysis showed crack formation in the tensile zone. Microstructural evidence showed that cracks propagate through the adiabatic shear bands by Dimple-Void mechanism. However, voids formation before shear banding also occurred. In both mechanisms adiabatic shear bands are formed via dynamic recrystallization where the alpha–beta interphase works as stress concentrator promoting the formation of dimples and voids.

  4. ALMA Band 5 Cartridge Performance

    Science.gov (United States)

    Billade, Bhushan; Lapkin, I.; Nystrom, O.; Sundin, E.; Fredrixon, M.; Finger, R.; Rashid, H.; Desmaris, V.; Meledin, D.; Pavolotsky, A.; Belitsky, Victor

    2010-03-01

    Work presented here concerns the design and performance of the ALMA Band 5 cold cartridge, one of the 10 frequency channels of ALMA project, a radio interferometer under construction at Atacama Desert in Chile. The Band 5 cartridge is a dual polarization receiver with the polarization separation performed by orthomode transducer (OMT). For each polarization, Band 5 receiver employs sideband rejection (2SB) scheme based on quadrature layout, with SIS mixers covering 163-211 GHz with 4-8 GHz IF. The LO injection circuitry is integrated with mixer chip and is implemented on the same substrate, resulting in a compact 2SB assembly. Amongst the other ALMA bands, the ALMA Band 5 being the lowest frequency band that uses all cold optics, has the largest mirror. Consequently, ALMA Band 5 mirror along with its support structure leaves very little room for placing OMT, mixers and IF subsystems. The constraints put by the size of cold optics and limited cartridge space, required of us to revise the original 2SB design and adopt a design where all the components like OMT, mixer, IF hybrid, isolators and IF amplifier are directly connected to each other without using any co-ax cables in-between. The IF subsystem uses the space between 4 K and 15 K stage of the cartridge and is thermally connected to 4 K stage. Avoiding co-ax cabling required use of custom designed IF hybrid, furthermore, due to limited cooling capacity at 4 K stage, resistive bias circuitry for the mixers is moved to 15 K stage and the IF hybrid along with an integrated bias-T is implemented using superconducting micro-strip lines. The E-probes for both LO and RF waveguide-to-microstrip transitions are placed perpendicular to the wave direction (back-piece configuration). The RF choke at the end of the probes provides a virtual ground for the RF/LO signal, and the choke is DC grounded to the chassis. The on-chip LO injection is done using a microstrip line directional coupler with slot-line branches in the

  5. The Novel Microwave Stop-Band Filter

    Directory of Open Access Journals (Sweden)

    R. E. Chernobrovkin

    2008-01-01

    Full Text Available The stop-band filter with the new band-rejection element is proposed. The element is a coaxial waveguide with the slot in the centre conductor. In the frame of this research, the numerical and experimental investigations of the amplitude-frequency characteristics of the filter are carried out. It is noted that according to the slot parameters the two typical resonances (half-wave and quarter-wave can be excited. The rejection band of the single element is defined by the width, depth, and dielectric filling of the slot. Fifth-order Chebyshev filter utilizing the aforementioned element is also synthesized, manufactured, and tested. The measured and simulated results are in good agreement. The experimental filter prototype exhibits the rejection band 0.86 GHz at the level −40 dB.

  6. Magnetic Dipole Band in 113^In

    Institute of Scientific and Technical Information of China (English)

    马克岩; 杨东; 陆景彬; 王烈林; 王辉东; 刘运祚; 刘弓冶; 李黎; 马英君; 杨森; 李广生; 贺创业; 李雪琴

    2012-01-01

    High spin states in the odd-A nucleus 113^In have been investigated using the re- action 110^Pd(7^Li, 4n) at a beam energy of 50 MeV. A new positive parity dipole band with the configuration of π(g9/2)^-lv(h11/2)^2 v (g7/2)^2 is established. The effective interaction V(θ) values of this band have been successfully described by a semiclassical geometric model based on shear mechanism, which show that the dipole band has the characteristics of magnetic rotation. In addition the collective rotational angular momentum for this band is extracted. The results show that the core contribution increases gradually with the increase of the rotation frequency.

  7. Minimal model for beta relaxation in viscous liquids

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Olsen, Niels Boye

    2003-01-01

    Contrasts between beta relaxation in equilibrium viscous liquids and glasses are rationalized in terms of a double-well potential model with structure-dependent asymmetry, assuming structure is described by a single order parameter. The model is tested for tripropylene glycol where it accounts...... for the hysteresis of the dielectric beta loss peak frequency and magnitude during cooling and reheating through the glass transition....

  8. Reconfigurable, Wideband Radar Transceiver and Antenna for P-band Stretch Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — IAI proposes to develop a Reconfigurable Wideband Radar Transceiver, with direct digital synthesis of P-band radar frequencies, novel high bandwidth P-band antenna...

  9. Design and Simulation of Edge-Coupled Stripline Band Pass Filter for U band

    OpenAIRE

    Pawan Shakdwipee

    2013-01-01

    In this paper, a band pass filter structure using Ansoft designer software and Matlab software simulation tool are presented. The filter is operated at U Band range in higher order 50 GHz edge-coupled Stripline band pass filter for different microwave application. For the proposed work we consider simulation using Roger R03203 substrate with dielectric constant of 3.02, Conductor Thickness 0.035 mm and Substrate Height 0.787 mm. This filter is design at a center frequency of 50 GHz with 8 GHz...

  10. Anodic oxides on a beta type Nb-Ti alloy and their characterization by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Woldemedhin, Michael Teka; Hassel, Achim Walter [Max Planck Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz (Austria); Raabe, Dierk [Max Planck Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    2010-04-15

    Anodic oxides were grown on the surface of an electropolished (Ti-30 at% Nb) beta-titanium ({beta}-Ti) alloy by cyclic voltammetry. The scan rate was 100 mV s{sup -1} between 0 and 8 V in increments of l V in an acetate buffer of pH 6.0. Electrochemical impedance spectroscopy was carried out right after each anodic oxide growth increment to study the electronic properties of the oxide/electrolyte interface in a wide frequency range from 100 kHz to 10 MHz with an AC perturbation voltage of 10 mV. A film formation factor of 2.4 nm V{sup -1} was found and a relative permittivity number (dielectric constant) of 42.4 was determined for the oxide film formed. Mott-Schottky analysis on a potentiostatically formed 7 nm thick oxide film was performed to assess the semiconducting properties of the mixed anodic oxide grown on the alloy. A flat band potential of -0.47 V (standard hydrogen electrode, SHE) was determined, connected to a donor density of 8.2 x 10{sup 17} cm{sup -3}. {beta}-Ti being highly isotropic in terms of mechanical properties should be superior to the stiffer {alpha}-Ti compound. Its application, however, requires a passivation behaviour comparable or better than {alpha}-Ti which in fact is found. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  11. Design and analysis of defected ground structure transformer for dual-band antenna

    Directory of Open Access Journals (Sweden)

    Wai-Wa Choi

    2014-12-01

    Full Text Available This study presents a novel dual-band antenna design methodology utilising a dual-frequency impedance transformer with defected ground structure (DGS. The proposed dual-frequency DGS impedance transformer generates a second resonant frequency from a conventional single-band antenna, resulting dual-band operation. Simulation studies illustrate that the adopted design achieves versatile configurations for arbitrary operating frequencies and diverse input impedance ranges in planar antenna structures. To experimentally verify the proposed design methodology, a dual-frequency DGS impedance transformer was implemented for a 2.4 GHz monopole antenna to obtain a 900/2400 MHz dual-band antenna. Measurement shows that the 10 dB return loss bandwidth in 900 MHz band is 34.4 MHz, whereas that in 2400 MHz band is wider than 530 MHz. Typical monopole radiation patterns are observed at both operating bands.

  12. Increased Low- and High-Frequency Oscillatory Activity in the Prefrontal Cortex of Fibromyalgia Patients

    Science.gov (United States)

    Lim, Manyoel; Kim, June Sic; Kim, Dajung J.; Chung, Chun Kee

    2016-01-01

    Recent human neuroimaging studies have suggested that fibromyalgia (FM), a chronic widespread pain disorder, exhibits altered thalamic structure and function. Since the thalamus has extensive reciprocal connection with the cortex, structural and functional thalamic alterations in FM might be linked to aberrant thalamocortical oscillation. This study investigated the presence of abnormal brain rhythmicity in low- and high-frequency bands during resting state in patients with FM and their relationship to clinical pain symptom. Spontaneous magnetoencephalography (MEG) activity was recorded in 18 females with FM and 18 age- and sex-matched healthy control (HC) subjects. The most remarkable finding was that FM patients had general increases in theta, beta and gamma power along with a slowing of the dominant alpha peak. Increased spectral powers in the theta-band were primarily localized to the left dorsolateral prefrontal (DLPFC) and orbitofrontal cortex (OFC). Beta and gamma over-activation were localized to insular, primary motor and primary and secondary somatosensory (S2) cortices, as well as the DLPFC and OFC. Furthermore, enhanced high-frequency oscillatory activities in the DLPFC and OFC were associated with higher affective pain scores in patients with FM. Our results demonstrate that FM patients feature enhanced low- and high-frequency oscillatory activity in the brain areas related to cognitive and emotional modulation of pain. Increased low- and high-frequency activity of the prefrontal cortex may contribute to persistent perception of pain in FM. Therapeutic intervention based on manipulating neural oscillation to restore normal thalamocortical rhythmicity may be beneficial to pain relief in FM. PMID:27014041

  13. Iliotibial band friction syndrome.

    Science.gov (United States)

    Lavine, Ronald

    2010-07-20

    Published articles on iliotibial band friction syndrome have been reviewed. These articles cover the epidemiology, etiology, anatomy, pathology, prevention, and treatment of the condition. This article describes (1) the various etiological models that have been proposed to explain iliotibial band friction syndrome; (2) some of the imaging methods, research studies, and clinical experiences that support or call into question these various models; (3) commonly proposed treatment methods for iliotibial band friction syndrome; and (4) the rationale behind these methods and the clinical outcome studies that support their efficacy.

  14. EMISAR: C- and L-band polarimetric and interferometric SAR

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Dall, Jørgen; Skou, Niels;

    1996-01-01

    EMISAR is a C- and L-band fully polarimetric (i.e. 4 complex channel per frequency) synthetic aperture radar designed for remote sensing with high demands for resolution (2 m), polarization discrimination, and absolute radiometric and polarimetric calibration. The present installation has one 3-a......-axes stabilized antenna (C- or L-band) and two flush mounted C-band antennas providing the system with cross track and repeat track interferometric capabilities...

  15. A novel L-band polarimetric radiometer featuring subharmonic sampling

    DEFF Research Database (Denmark)

    Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D conv...... converter at a frequency well below L-band. Overall stability has been a design driver, as the instrument is intended for airborne measurements of polarimetric sea signatures....

  16. Event-Related Beta EEG Changes During Active, Passive Movement and Functional Electrical Stimulation of the Lower Limb.

    Science.gov (United States)

    Qiu, Shuang; Yi, Weibo; Xu, Jiapeng; Qi, Hongzhi; Du, Jingang; Wang, Chunfang; He, Feng; Ming, Dong

    2016-02-01

    A number of electroencephalographic (EEG) studies have reported on event-related desynchronization/synchronization (ERD/ERS) during active movements, passive movements, and the movements induced by functional electrical stimulation (FES). However, the quantitative differences in ERD values and affected frequency bands associated with the lower limb have not been discussed. The goal of this paper was to quantitatively compare the ERD patterns during active movement, passive movement and FES-induced movement of the lower limb. 64-channel EEG signals were recorded to investigate the brain oscillatory patterns during active movement, passive movement and FES-induced movement of the lower limb in twelve healthy subjects. And passive movement and FES-induced movement were also performed in a hemiplegic stroke patient. For healthy subjects, FES-induced movement presented significantly higher characteristic frequency of central beta ERD while there was no significant difference in ERD values compared with active or passive movement. Meanwhile, beta ERD values of FES-induced movement were significantly correlated with those of active movement, and spatial distribution of beta ERD pattern for FES-induced movement was more correlated with that for active movement. In addition, the stroke patient presented central ERD patterns during FES-induced movement, while no ERD with similar frequencies could be found during passive movement. This work implies that the EEG oscillatory pattern under FES-induced movement tends more towards active movement instead of passive movement. The quantification of ERD patterns could be expected as a potential technique to evaluate the brain response during FES-induced movement. PMID:26441422

  17. THE GEMINI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF GIANT PLANETS AROUND DEBRIS DISK STARS

    Energy Technology Data Exchange (ETDEWEB)

    Wahhaj, Zahed [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile); Liu, Michael C.; Nielsen, Eric L.; Ftaclas, Christ; Chun, Mark [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Biller, Beth A. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Hayward, Thomas L. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Close, Laird M.; Males, Jared R.; Skemer, Andrew [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Thatte, Niranjan; Tecza, Matthias [Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Kuchner, Marc [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Greenbelt, MD 20771 (United States); Reid, I. Neill [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); De Gouveia Dal Pino, Elisabete M.; Gregorio-Hetem, Jane [Departamento de Astronomia, Universidade de Sao Paulo, IAG/USP, Rua do Matao 1226, 05508-900 Sao Paulo, SP (Brazil); Alencar, Silvia H. P. [Departamento de Fisica-ICEx-UFMG, Av. Antonio Carlos 6627, 30270-901 Belo Horizonte, MG (Brazil); Boss, Alan [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Lin, Douglas N. C. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States); and others

    2013-08-20

    We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known {beta} Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a {>=}5 M{sub Jup} planet beyond 80 AU, and <21% of debris disk stars have a {>=}3 M{sub Jup} planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d {sup 2} N/dMda{proportional_to}m {sup {alpha}} a {sup {beta}}, where m is planet mass and a is orbital semi-major axis (with a maximum value of a{sub max}). We find that {beta} < -0.8 and/or {alpha} > 1.7. Likewise, we find that {beta} < -0.8 and/or a{sub max} < 200 AU. For the case where the planet frequency rises sharply with mass ({alpha} > 1.7), this occurs because all the planets detected to date have masses above 5 M{sub Jup}, but planets of lower mass could easily have been detected by our search. If we ignore the {beta} Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a {>=}3 M{sub Jup} planet beyond 10 AU, and {beta} < -0.8 and/or {alpha} < -1.5. Likewise, {beta} < -0.8 and/or a{sub max} < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence

  18. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.;

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...

  19. Double beta decay experiments

    International Nuclear Information System (INIS)

    The great sensitivity of double beta decay to neutrino mass and right handed currents has motivated many new and exciting attempts to observe this elusive nuclear phenomenon directly. Experiments in operation and other coming on line in the next one or two years are expected to result in order-of-magnitude improvements in detectable half lives for both the two-neutrino and no-neutrino modes. A brief history of double beta decay experiments is presented together with a discussion of current experimental efforts, including a gas filled time projection chamber being used to study selenium-82. (author)

  20. Laparoscopic gastric banding

    Science.gov (United States)

    ... make the band tighter or looser any time after you have this surgery. It may be tightened or ... Having problems eating Not losing enough weight Vomiting after you eat Outlook (Prognosis) The final weight loss with ...

  1. CSF oligoclonal banding - slideshow

    Science.gov (United States)

    ... presentations/100145.htm CSF oligoclonal banding - series—Normal anatomy ... Overview The cerebrospinal fluid (CSF) serves to supply nutrients to the central nervous system (CNS) and collect waste products, as well as ...

  2. 基于L波段Stokes参数遥感数据射频干扰检测及特性分析%Radio Frequency Interference Detection and Characteristic Analysis Based on the L Band Stokes Parameters Remote Sensing Data

    Institute of Scientific and Technical Information of China (English)

    王新新; 王祥; 韩震; 杨建洪

    2015-01-01

    Sea surface salinity remote sensing is seriously impacted by Radio Frequency Interference (RFI) over coastal areas, detecting RFI sources and analyzing its influence characteristic for developing RFI suppression research in the nearshore areas is of great significance. Based on the unique multi-angle observation imaging and polarization characteristics of the SMOS satellite sensor MIRAS, this paper generates the RFI sources distribution diagram and analyzes its distribution characteristics and influence scope through synthesis third and fouth Stokes parameters in the China sea. The results indicate that the RFI sources are concentrated distributed throughout coastal land areas of the Bohai sea, the Yellow sea, the west of the East China Sea and the north of the south China sea are strong impacted by RFI sources, and the sources have big different effects on ascending pass and descending pass data. The RFI sources may be microwave emission station, displaying as pointlike radio source, and the strong sources can pollute satellite data within a few hundred kilometers through antenna sidelobes, and RFI suppression is a scientific problem right now for the reason that RFI has complex effects on satellite depending on different attenuation and antenna radiation patterns.%近岸海域盐度卫星微波遥感精度受射频干扰(RFI)严重影响,针对近岸海域检测RFI源并分析其影响特性对后续开展射频干扰抑制研究具有重要意义。该文基于SMOS卫星传感器MIRAS 独特的全极化特性,以中国海域沿岸陆地为研究区域,通过合成第3、第4 Stokes参数来表征RFI源的辐射强度,生成了RFI源分布图并分析了其影响范围。研究结果表明,影响中国海域的 RFI 源主要分布于中国沿海陆地区域,渤、黄海全部、东海的西部及南海的北部受RFI污染严重,卫星降轨数据和升轨数据受RFI影响具有很大的差异性。RFI源主要可能是微波发射

  3. Iliotibial band friction syndrome

    OpenAIRE

    Lavine, Ronald

    2010-01-01

    Published articles on iliotibial band friction syndrome have been reviewed. These articles cover the epidemiology, etiology, anatomy, pathology, prevention, and treatment of the condition. This article describes (1) the various etiological models that have been proposed to explain iliotibial band friction syndrome; (2) some of the imaging methods, research studies, and clinical experiences that support or call into question these various models; (3) commonly proposed treatment methods for ili...

  4. Band selection study for SMILES-2

    Science.gov (United States)

    Suzuki, Makoto; Shiotani, Masato; Ochiai, Satoshi; Baron, Philippe; Manago, Naohiro; Nishibori, Toshiyuki; Mizuno, Akira; Ozeki, Hiroyuki; Uzawa, Yoshinori; Maezawa, Hiroyuki

    2016-07-01

    Submillimeter limb sounding is very useful technique to investigate Earth's middle atmosphere since it can measure both reactive minor species (ClO, BrO, HO¬2, etc) and stable species (O3, HCl, etc) at day/night conditions as already established by UARS/MLS, Odin/SMR, and Aura/MLS. Superconducting Submillimeter-Wave Limb-emission Sounder (SMILES) was the first instrument to use 4K cooled SIS (Superconductor-Insulator-Superconductor) detection system for the limb sounding of the atmosphere in the frequency regions 625 GHz (Bands A and B) and 650 GHz (Band C) [1]. It has demonstrated its very high sensitivity (System Temperature, Tsys ~250K) for measuring stratospheric and mesospheric species, O3, HCl, ClO, HO2, HOCl, BrO, and O3 isotopes from Oct. 12, 2009 to Apr. 21, 2010 [2-5]. Since SMILES operation has terminated after only 6 months operation due to failure of sub-mm local oscillator (and later 4K cooler system), there exist strong scientific demand to develop successor of SMILES, the SMILES-2, which has optimized and enhanced frequency coverage to observe: (a) BrO and HOCl without interferences of stronger emission lines, (b) N2O, H2O, NO2, and CH3Cl not covered by the SMILES frequency regions, and (c) O2 line to measure temperature. This paper discusses possible SMILES-2 band selection considering limited instrument resources (number of SIS mixers and sub-mm local oscillator) and scientific requirements. This paper describes current status of SMILES-2 band selection study; (1) known issues of SMILES observations, (2) SMILES-2 scientific requirements, (3) methods of band selection study, (4) temperature, horizontal wind speed, H2O sensitivity study, (5) BrO and HOCl line selection, and (6) current band selection and possible instrument design.

  5. Word class and context affect alpha-band oscillatory dynamics in an older population

    Directory of Open Access Journals (Sweden)

    Monika eMellem

    2012-04-01

    Full Text Available Differences in the oscillatory EEG dynamics of reading open class and closed class words have previously been found (Bastiaansen et al., 2005 and are thought to reflect differences in lexical-semantic content between these word classes. In particular, the theta band (4–7 Hz seems to play a prominent role in lexical-semantic retrieval. We tested whether this theta effect is robust in an older population of subjects. Additionally, we examined how the context of a word can modulate the oscillatory dynamics underlying retrieval for the two different classes of words. Older participants (mean age 55 read words presented in either syntactically-correct sentences or in a scrambled order (scrambled sentence while their EEG was recorded. We performed time-frequency analysis to examine how power varied based on the context or class of the word. We observed larger power decreases in the alpha (8–12Hz band between 200–700 ms for the open class compared to closed class words, but this was true only for the scrambled sentence context. We did not observe differences in theta power between these conditions. Context exerted an effect on the alpha and low beta (13–18 Hz bands between 0–700 ms. These results suggest that the previously observed word class effects on theta power changes in a younger participant sample do not seem to be a robust effect in this older population. Though this is an indirect comparison between studies, it may suggest the existence of aging effects on word retrieval dynamics for different populations. Additionally, the interaction between word class and context suggests that word retrieval mechanisms interact with sentence-level comprehension mechanisms in the alpha band.

  6. DUAL MODE WIDEBAND BAND-PASS FILTER WITH NOTCHED BAND FOR COMMUNICATION SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Wang Hui; Yang Guo; Wu Wen; Ge Sheng

    2011-01-01

    This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz.The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at φ -90° and φ =0°,respectively.A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity.By using a parallel-coupled feed line,a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%.The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic,the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with -34.43 dB to 2.065 GHz with -2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with -2.873 dB to 3.507 GHz with -28.42 dB).This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz.Having been presented in this article,the measurement results agree well with the simulation results,which validates our idea.

  7. Formation of Degenerate Band Gaps in Layered Systems

    Directory of Open Access Journals (Sweden)

    Alexey P. Vinogradov

    2012-06-01

    Full Text Available In the review, peculiarities of spectra of one-dimensional photonic crystals made of anisotropic and/or magnetooptic materials are considered. The attention is focused on band gaps of a special type—the so called degenerate band gaps which are degenerate with respect to polarization. Mechanisms of formation and properties of these band gaps are analyzed. Peculiarities of spectra of photonic crystals that arise due to the linkage between band gaps are discussed. Particularly, it is shown that formation of a frozen mode is caused by linkage between Brillouin and degenerate band gaps. Also, existence of the optical Borrmann effect at the boundaries of degenerate band gaps and optical Tamm states at the frequencies of degenerate band gaps are analyzed.

  8. Joint selection of time segment and frequency band for classifying multiclass motor imagery EEG data%基于时间段和频带联合选择的多类运动想象脑电数据分类

    Institute of Scientific and Technical Information of China (English)

    魏庆国; 韩仁香

    2014-01-01

    The time and frequency intervals of EEG signals have significant influence on the classification performance of brain-computer interfaces(BCIs).Based on joint selection of time segment and frequency band,a new classification algorithm was proposed to classify multiclass motor imagery BCI systems in this paper.A sliding window was firstly used to segment the EEG signals in time and frequency domain.Then the multiclass common spatial pattern(CSP)was utilized for feature extraction in each pair of time and fre-quency segment.Finally we employed the k-nearest neighbor(KNN)to classify the extracted feature sig-nals.Cross-validated classification accuracy was used for the selection criterion of optimal time and frequen-cy segment.The performance of the algorithm was tested and compared with those of three typical algo-rithms by a classification experiment on a four-class data set.The results suggested that the algorithm could achieve a highest accuracy rate,validating the effectiveness of the j oint selection of time segment and frequency band based classification algorithm.%脑电信号的时间和频率间隔选择对脑机接口的分类性能具有重要的影响。针对多类运动想象脑机接口系统,提出一个新的基于时间段和频带联合选择的分类算法。该算法首先使用滑动窗将运动想象产生的脑电信号在时域和频域进行分割,然后在每一对截取的时间段和频段,使用多类共空域模式算法提取脑电特征信号,最后使用k-最近邻算法对特征信号进行分类。交叉验证的分类识别率作为最优时间段和频带的选择标准。使用一个四类数据集对这个分类算法的性能进行了测试。与现有的3个典型算法比较,这个算法取得了最高的平均分类正确率,证实了这个基于时间段和频带联合选择的分类算法的有效性。

  9. Ka-band waveguide rotary joint

    KAUST Repository

    Yevdokymov, Anatoliy

    2013-04-11

    The authors present a design of a waveguide rotary joint operating in Ka-band with central frequency of 33 GHz, which also acts as an antenna mount. The main unit consists of two flanges with a clearance between them; one of the flanges has three circular choke grooves. Utilisation of three choke grooves allows larger operating clearance. Two prototypes of the rotary joint have been manufactured and experimentally studied. The observed loss is from 0.4 to 0.8 dB in 1.5 GHz band.

  10. Maximizing band gaps in plate structures

    DEFF Research Database (Denmark)

    Halkjær, Søren; Sigmund, Ole; Jensen, Jakob Søndergaard

    2006-01-01

    Band gaps, i.e., frequency ranges in which waves cannot propagate, can be found in elastic structures for which there is a certain periodic modulation of the material properties or structure. In this paper, we maximize the band gap size for bending waves in a Mindlin plate. We analyze an infinite...... periodic plate using Bloch theory, which conveniently reduces the maximization problem to that of a single base cell. Secondly, we construct a finite periodic plate using a number of the optimized base cells in a postprocessed version. The dynamic properties of the finite plate are investigated...

  11. High frequency deep brain stimulation attenuates subthalamic and cortical rhythms in Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Diane eWhitmer

    2012-06-01

    Full Text Available Parkinson’s disease (PD is marked by excessive synchronous activity in the beta (8-35 Hz band throughout the cortico-basal ganglia network. The optimal location of high frequency deep brain stimulation (HF DBS within the subthalamic nucleus (STN region and the location of maximal beta hypersynchrony are currently matters of debate. Additionally, the effect of STN HF DBS on neural synchrony in functionally connected regions of motor cortex is unknown and of great interest. Scalp EEG studies demonstrated that stimulation of the STN can activate motor cortex antidromically, but the spatial specificity of this effect has not been examined. The present study examined the effect of STN HF DBS on neural synchrony within the cortico-basal ganglia network in patients with PD. We measured local field potentials dorsal to and within the STN of PD patients, and additionally in the motor cortex in a subset of these patients. We used diffusion tensor imaging (DTI to guide the placement of subdural cortical surface electrodes over the DTI-identified origin of the hyperdirect pathway between motor cortex and the STN. The results demonstrated that local beta power was attenuated during HF DBS both dorsal to and within the STN. The degree of attenuation was monotonic with increased DBS voltages in both locations, but this voltage-dependent effect was greater in the central STN than dorsal to the STN (p < 0.05. Cortical signals over the estimated origin of the hyperdirect pathway also demonstrated attenuation of beta hypersynchrony during DBS dorsal to or within STN, whereas signals from non-specific regions of motor cortex were not attenuated. The spatially specific suppression of beta synchrony in the motor cortex support the hypothesis that DBS may treat Parkinsonism by reducing excessive synchrony in the functionally connected sensorimotor network.

  12. Evaluation of neutrino masses from $m_{\\beta\\beta}$ values

    CERN Document Server

    Khrushchov, V V

    2008-01-01

    A neutrino mass matrix is considered under conditions of the CP invariance and the negligible reactor mixing $\\theta_{13}$ angle. Absolute mass values for three neutrinos are evaluated in normal and inverted hierarchy spectra on the ground of data for oscillation mixing neutrino parameters and effective neutrino mass entering into a probability of neutrinoless two beta decay $m_{\\beta\\beta}$ values.

  13. Trichoderma .beta.-glucosidase

    Science.gov (United States)

    Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian

    2006-01-03

    The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.

  14. Applied Beta Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Rich, B.L.

    1986-01-01

    Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements.

  15. Neutrinoless Double Beta Decay

    CERN Document Server

    Päs, Heinrich

    2015-01-01

    We review the potential to probe new physics with neutrinoless double beta decay $(A,Z) \\to (A,Z+2) + 2 e^-$. Both the standard long-range light neutrino mechanism as well as short-range mechanisms mediated by heavy particles are discussed. We also stress aspects of the connection to lepton number violation at colliders and the implications for baryogenesis.

  16. Dual-band Monopole Antenna with Stagger-tuned Arms for Broadbanding

    OpenAIRE

    Ammann, Max; Farrell, R.

    2005-01-01

    The paper describes a dual-band miniaturized printed monopole for integration in modern wireless systems. The printed monopole is augmented with two arms, resonant at slightly different frequencies, providing a broadened response for the upper band. The achieved bandwidth for the high band is 36%. These antennas are proposed for the emerging dual-mode multi-band WLAN transceivers, which operate over a wide range of bands as dictated by national authorities. Measured and simulated data, includ...

  17. Multi-Band Feeds: A Design Study

    CERN Document Server

    Maan, Yogesh; Raja, Wasim; Mehta, Nikhil

    2012-01-01

    Broadband antenna feeds are of particular interest to existing and future radio telescopes for multi-frequency studies of astronomical sources. Although a 1:15 range in frequency is difficult to achieve, the well-known Eleven feed design offers a relatively uniform response over such a range, and reasonably well-matched responses in E & H planes. However, given the severe Radio Frequency Interference in several bands over such wide spectral range, one desires to selectively reject the corresponding bands. With this view, we have explored the possibilities of having a multi-band feed antenna spanning a wide frequency range, but which would have good response only in a number of pre-selected (relatively) RFI-free windows (for a particular telescope-site). The designs we have investigated use the basic configuration of pairs of dipoles as in the Eleven feed, but use simple wire dipoles instead of folded dipoles used in the latter. From our study of the two designs we have investigated, we find that the desig...

  18. Achieving Fine Beta Grain Structure in a Metastable Beta Titanium Alloy Through Multiple Forging-Annealing Cycles

    Science.gov (United States)

    Zafari, Ahmad; Ding, Yunpeng; Cui, Jianzhong; Xia, Kenong

    2016-07-01

    A coarse-grained (order of 1 mm) Ti-5553 metastable beta alloy was subjected to multiple passes of low-temperature forging and multiple forging plus annealing cycles, respectively. In the forging only processing, strain was concentrated in the shear bands formed and accumulated with each forging pass, resulting in a heterogeneous microstructure and eventual cracking along the shear bands. In contrast, the introduction of a short beta annealing after each forging step led to fine recrystallized grains (50 to 100 µm) formed in the shear bands, and a uniformly refined beta grain structure after four cycles. This is attributed to the strengthening effect of the fine grains, causing redistribution of most severe strains to the coarse grain region in the subsequent forging, consistent with the simulated results by finite element analysis. The analyses of the microstructures and simulated strain distributions revealed that the critical strain for recrystallization is between 0.2 and 0.5 and the strain to fracture to be ~0.8 to 0.9. The fine-grained (50 to 100 µm) beta alloy, however, fractured at a much smaller strain of <0.4 during the next forging step, owing to the formation of stress-induced martensitic α″ which is more prevalent in fine grains than in coarse ones.

  19. Interferon Beta-1b Injection

    Science.gov (United States)

    Interferon beta-1b injection is used to reduce episodes of symptoms in patients with relapsing-remitting (course ... and problems with vision, speech, and bladder control). Interferon beta-1b is in a class of medications ...

  20. Genetics Home Reference: beta thalassemia

    Science.gov (United States)

    ... for Disease Control and Prevention Centre for Genetics Education (Australia) Cold Spring Harbor Laboratory: Your Genes Your Health Disease InfoSearch: Beta Thalassemia Genomics Education Programme (UK) MalaCards: dominant beta-thalassemia Merck Manual ...

  1. Multichannel frequency dividers using MSW

    OpenAIRE

    Zavislyak, I. V.; Romanyuk, V. F.; Stakhursky, L. L.

    1997-01-01

    Multichannel frequency dividers (multiplexers) are obligatory elements of many radar and communication systems. They are first of all used when signal processing in the real time is needed within the band of several GHz [1].The frequency dividers using magnetostatic waves (MSW) and resonances (MSR) are perspective devices in spite of the problems connected with low termostability of their electric characteristics. The use of the epitaxial films of yttrium-iron garnet (YIG), barium ferrite (BF...

  2. Loaded-frequency selective surface

    Institute of Scientific and Technical Information of China (English)

    Qiang GAO; Dunbao YAN; Yunqi FU; Naichang YUAN

    2008-01-01

    A new frequency-selective surface (FSS) with loadings is introduced in this paper and analyzed by way of period moment methods (PMMs). The simulated results show that FSS may operate in different bands and especially generate a large reduction in the resonant frequency for a fixed unit cell size through different loadings. This provides a new orientation in the develop-ment for FSS. Practical circuits are fabricated, and the measured results agree well with the simulated results.

  3. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    BACKGROUND. Beta emitters, such as 90Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding. AIM. To discuss practical precautions for handling beta emitters...... on the outside of the primary shielding material. If suitable shielding is used and larger numbers of handlings are divided among several persons, then handling of beta emitters can be a safe procedure....

  4. Photonic band gap materials

    Science.gov (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  5. 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

  6. Misleading Betas: An Educational Example

    Science.gov (United States)

    Chong, James; Halcoussis, Dennis; Phillips, G. Michael

    2012-01-01

    The dual-beta model is a generalization of the CAPM model. In the dual-beta model, separate beta estimates are provided for up-market and down-market days. This paper uses the historical "Anscombe quartet" results which illustrated how very different datasets can produce the same regression coefficients to motivate a discussion of the…

  7. TGF-beta and osteoarthritis.

    NARCIS (Netherlands)

    Blaney Davidson, E.N.; Kraan, P.M. van der; Berg, W.B. van den

    2007-01-01

    OBJECTIVE: Cartilage damage is a major problem in osteoarthritis (OA). Growth factors like transforming growth factor-beta (TGF-beta) have great potential in cartilage repair. In this review, we will focus on the potential therapeutic intervention in OA with TGF-beta, application of the growth facto

  8. The characteristic of power flow in broad band dynamic vibration absorber

    Institute of Scientific and Technical Information of China (English)

    WANG Minqing; SHENG Meiping; SUN Jincai; LIU Yi

    2002-01-01

    DVA (dynamic vibration absorber) is good for restrain of the resonance vibration in low frequency, especially under the condition that there are only one mode or two modes in a frequency band. It seems rather difficult to control the resonance vibration of elastic structures in high frequency, since usually there are so many modes in high frequency band. The broad band DVA is brought forward to reduce the resonance vibration of elastic structures. The broad band DVA is designed on the basis of the characteristic of power flow in structure in this paper.The broad band DVA is effective on absorbing the resonance vibration power flow of the mostimportant modes. The ability of absorbing vibration for the broad band DVA is analyzed indetail. The results obtained in this paper provide a basis for the optimization design of thebroad band DVA and the optimization positions on structures.

  9. 47 CFR 101.147 - Frequency assignments.

    Science.gov (United States)

    2010-10-01

    ...-case basis to Government or non-Government space research earth stations for telecommand purposes in connection with deep space research. (8) This frequency band is shared with station(s) in the Local... shared with space stations (space to earth) in the fixed-satellite service. (10) This band is...

  10. An Electrostatically Actuated MEMS Arch Band-Pass Filter

    Directory of Open Access Journals (Sweden)

    Hassen M. Ouakad

    2013-01-01

    Full Text Available This work presents an investigation of the dynamics of micromachined arches resonators and their potential to be utilized as band-pass filters. The arches are actuated by a DC electrostatic load superimposed to an AC harmonic load. The dynamic response of the arch is studied analytically using a Galerkin-based reduced-order model when excited near its fundamental and third natural frequencies. Several simulation results are presented demonstrating interesting jumps and snap-through behavior of the arches and their attractive features for uses as band-pass filters, such as their sharp roll-off from pass bands to stop bands and their flat response.

  11. Design of Stacked Microstrip Dual-band Circular Polarized Antenna

    Directory of Open Access Journals (Sweden)

    N. Zakaria

    2012-09-01

    Full Text Available This study introduces a new design of dual-band circular polarized (CP microstrip antenna for ISM band applications (2.45 GHz and 5.8 GHz. The proposed dual-band CP microstrip antenna with compact design has achieved design intention of having return loss of < −10 dB and axial ratio of < 3 dB for both frequencies of 2.45 GHz and 5.8 GHz. The antenna has been successfully designed, fabricated, simulated, and measured and it shows the advantages of good dual-band and CP performances. Thus, the obtained results confirm satisfactory performance and good agreement.

  12. Band-monitoring Payload for a CubeSat Satellite

    Directory of Open Access Journals (Sweden)

    P. Vagner

    2012-04-01

    Full Text Available During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we have designed a band-monitoring payload for an experimental CubeSat satellite. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band, and a transmitter with FM modulation in UHF downlink band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations.

  13. Italian Science Case for ALMA Band 2+3

    CERN Document Server

    Beltran, M T; Brand, J; Casasola, V; Cesaroni, R; Codella, C; Fontani, F; Gregorini, L; Guidi, G; Hunt, L; Liuzzo, E; Marconi, A; Massardi, M; Moscadelli, L; Paladini, R; Podio, L; Prandoni, I; Rygl, K L J; Rivilla, V; .,; Testi, L

    2015-01-01

    The Premiale Project "Science and Technology in Italy for the upgraded ALMA Observatory - iALMA" has the goal of strengthening the scientific, technological and industrial Italian contribution to the Atacama Large Millimeter/submillimeter Array (ALMA), the largest ground based international infrastructure for the study of the Universe in the microwave. One of the main objectives of the Science Working Group (SWG) inside iALMA, the Work Package 1, is to develop the Italian contribution to the Science Case for the ALMA Band 2 or Band 2+3 receiver. ALMA Band 2 receiver spans from ~67 GHz (bounded by an opaque line complex of ozone lines) up to 90 GHz which overlaps with the lower frequency end of ALMA Band 3. Receiver technology has advanced since the original definition of the ALMA frequency bands. It is now feasible to produce a single receiver which could cover the whole frequency range from 67 GHz to 116 GHz, encompassing Band 2 and Band 3 in a single receiver cartridge, a so called Band 2+3 system. In addit...

  14. Beta-plane turbulence: experiments with altimetry

    CERN Document Server

    Zhang, Y

    2013-01-01

    Results from a new series of experiments on flows generated by an electromagnetic method in a rotating tank with topographic beta-effect are presented. The velocity fields are measured by the Altimetric Imaging Velocimetry. The turbulent flows observed in the experiments develop zonal jets which are latent in a stationary forced-dissipative regime of the flow but become prominent in the decaying flow. The two-dimensional energy spectra of the flows exhibit the development of anisotropy towards zonal motions. The experiments demonstrate dual turbulent cascade with energy and enstrophy ranges. The frequency-wavenumber spectra reveal the presence of Rossby waves at low wavenumbers which are excited by the turbulent motions. The experimental results are compared with available theory of beta-plane turbulence.

  15. Development of S-band accelerating structure

    International Nuclear Information System (INIS)

    In Pohang Accelerator Laboratory (PAL) in Korea construction of XFEL (X-ray Free electron Lazar) institution is under construction aiming at the completion in 2014. Energy 10 GeV of the linac part of this institution and main frequency are planned in S-band (2856 MHz), and about 178 S-band 3m accelerating structures are due to be used for this linac. The oscillation of an X-ray laser requires very low emittance electron beam. On the other hand, since the accelerating structure which accelerates an electron beam has a feed port of microwave (iris), the electromagnetic field asymmetry of the microwave feeding device called coupler worsens the emittance of an electron beam. MHI manufactured two kinds of S-band accelerating structures with which the electromagnetic field asymmetry of coupler cavity was compensated for PALXFEL linac. We report these accelerating structures. (author)

  16. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  17. Low-frequency model of the microwave frequency (phase) detector with amplitude modulator and shift oscillator

    OpenAIRE

    Ri, Bak Son; Solodkov, O. V.; Chizhikova, E. V.

    2009-01-01

    A low-frequency model of the microwave frequency (phase) detector with amplitude modulator and shift generator has been studied theoretically and experimentally. The results of experiment indicate that such FM (PM) detector can be also used in the HF band of radio frequencies.

  18. Coupling between Fano and Bragg bands in photonic band structure of two-dimensional metallic photonic structures

    CERN Document Server

    Markos, Peter

    2016-01-01

    Frequency and transmission spectrum of two-dimensional array of metallic rods is investigated numerically. Based on the recent analysis of the band structure of two-dimensional photonic crystal with dielectric rods [P. Marko\\v{s}, Phys. Rev. A 92 043814 (2015)] we identify two types of bands in the frequency spectrum: Bragg (P) bands resulting from a periodicity and Fano (F) bands which arise from Fano resonances associated with each of the cylinders within the periodic structure. It is shown that the existence of Fano band in a certain frequency range is manifested by a Fano resonance in the transmittance. In particular, we re-examine the symmetry properties of the H- polarized band structure in the frequency range where the spectrum consists of the localized modes associated with the single scatterer resonances and we explore process of formation of Fano bands by identifying individual terms in the expansion of the LCAO states. We demonstrate how the interplay between the two scattering mechanisms affects p...

  19. Beta-thalassemia.

    Science.gov (United States)

    Galanello, Renzo; Origa, Raffaella

    2010-05-21

    Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis). Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta

  20. Beta-thalassemia

    Directory of Open Access Journals (Sweden)

    Origa Raffaella

    2010-05-01

    Full Text Available Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands, dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes, gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely

  1. Robust MPEG Watermarking in DWT Four Bands

    Directory of Open Access Journals (Sweden)

    E. Elbaşı

    2012-04-01

    Full Text Available In this paper, we generalize an idea in a recent paper that embeds a binary pattern in the form of a binary image in the wavelet domain for images. Our generalization includes all four bands (LL, LH, HL and HH in the DWT for MPEG video sequences. We tested the proposed algorithm against twelve attacks. Embedding the watermark in lower frequencies is robust to one group of attacks, and embedding the watermark in higher frequencies is robust to another group of attacks.

  2. S-NPP VIIRS on-orbit Band to Band Registration Estimation using the Moon

    Science.gov (United States)

    Choi, T.

    2015-12-01

    The Soumi National Polar-orbit Partnership (S-NPP) was successfully launched and has been operational since October 28, 2011, which carries the Visible Infrared Radiometer Suite (VIIRS) with among other instruments. Since VIIRS does not include on-board spatial calibrator such as Spectroradiometric Calibration Assembly (SRCA) on the predecessor sensor called MODerate resolution Imaging Spectroradiometer (MODIS), the on-orbit estimation of the spatial parameters needs to be measured independently. As a well-known radiometric target, the moon is utilized to estimate Band-to-Band (BBR) results as a part of spatial quality factors using the lifetime scheduled lunar collections. The reference band of the BBR is chosen to be the VIIRS band of Imaging band 1 (I1), because of its high signal-to-noise ratio, and high spatial sampling frequency compared to other moderate (M) bands. In this study, the conventional BBR calculation applied MODIS called weighted sum method is applied providing along-track and along-scan direction results. The BBR differences based on the reference band I1 results are very stable over the 3 years of VIIRS operation. The along-scan direction BBR results are mostly within ± 0.5 nominal Ground Sampling Distance (GSD) and the along-track direction BBR values are mostly between + 0.1 and -0.4 GSD. The final BBR results are available publically at the National Oceanic Atmospheric Agency (NOAA) Integrated Calibration Validation System (ICVS) webpage.

  3. Coroutine Sequencing in BETA

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger;

    In object-oriented programming, a program execution is viewed as a physical model of some real or imaginary part of the world. A language supporting object-oriented programming must therefore contain comprehensive facilities for modeling phenomena and concepts form the application domain. Many ap...... applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modeling objects that alternate between a number of sequential processes. The authors describe coroutines in BETA...

  4. Beta decay for pedestrians

    CERN Document Server

    Lipkin, Harry Jeannot

    1962-01-01

    The ""pedestrian approach"" was developed to describe some essentially simple experimental results and their theoretical implications in plain language. In this graduate-level text, Harry J. Lipkin presents simply, but without oversimplification, the aspects of beta decay that can be understood without reference to the formal theory; that is, the reactions that follow directly from conservation laws and elementary quantum mechanics.The pedestrian treatment is neither a substitute for a complete treatment nor a watered-down version.

  5. Integration of BETA with Eclipse

    DEFF Research Database (Denmark)

    Andersen, Peter; Madsen, Ole Lehrmann; Enevoldsen, Mads Brøgger

    2004-01-01

    This paper presents language interoperability issues appearing in order to implement support for the BETA language in the Java-based Eclipse integrated development environment. One of the challenges is to implement plug-ins in BETA and be able to load them in Eclipse. In order to do this, some form...... of language interoperability between Java and BETA is required. The first approach is to use the Java Native Interface and use C to bridge between Java and BETA. This results in a workable, but complicated solution. The second approach is to let the BETA compiler generate Java class files. With this approach...... it is possible to implement plug-ins in BETA and even inherit from Java classes. In the paper the two approaches are described together with part of the mapping from BETA to Java class files. http://www.sciencedirect.com/science/journal/15710661...

  6. Regulation of beta cell replication

    DEFF Research Database (Denmark)

    Lee, Ying C; Nielsen, Jens Høiriis

    2008-01-01

    Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been...... suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase...... inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether...

  7. Beta cell adaptation in pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin...... and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades......, but the mechanisms involved are still not clarified. In this review the information obtained in previous studies is recapitulated together with some of the current attempts to resolve the controversy in the field: identification of the putative progenitor cells, identification of the factors involved...

  8. Complex banded structures in directional solidification processes.

    Science.gov (United States)

    Korzhenevskii, A L; Rozas, R E; Horbach, J

    2016-01-27

    A combination of theory and numerical simulation is used to investigate impurity superstructures that form in rapid directional solidification (RDS) processes in the presence of a temperature gradient and a pulling velocity with an oscillatory component. Based on a capillary wave model, we show that the RDS processes are associated with a rich morphology of banded structures, including frequency locking and the transition to chaos.

  9. Colloquium: Topological band theory

    Science.gov (United States)

    Bansil, A.; Lin, Hsin; Das, Tanmoy

    2016-04-01

    The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. This review begins by discussing underpinnings of the topological band theory, which involve a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder and interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary, and quaternary compounds, transition metal and f -electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites, and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultrathin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. This Colloquium concludes by giving a perspective on research directions where further work will broadly benefit the topological materials field.

  10. Blazars at Low Radio Frequencies

    Science.gov (United States)

    Trüstedt, J.; Kadler, M.; Brüggen, M.; Falcke, H.; Heald, G.; McKean, J.; Mueller, C.; Ros, E.; Schulz, R.; Wilms, J.

    We explore the low radio-frequency properties of the MOJAVE 1 blazar sample using the LOFAR Multi-Frequency Snapshot Sky Survey (MSSS). We find the characteristically flat blazar spectrum to extend down to the LOFAR bands, demonstrating that the emission at these low radio frequencies is still dominated by relativistically beamed emission. As most sources remain unresolved at the MSSS angular resolution, we are reimaging these data using LOFAR baselines beyond the standard MSSS uv-range resulting in an angular resolution of ~24 arcsec. We present first LOFAR images of MOJAVE sources from this project.

  11. LHCb: $2\\beta_s$ measurement at LHCb

    CERN Multimedia

    Conti, G

    2009-01-01

    A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.

  12. Switched Band-Pass Filters for Adaptive Transceivers

    Science.gov (United States)

    Wang, Ray

    2007-01-01

    Switched band-pass filters are key components of proposed adaptive, software- defined radio transceivers that would be parts of envisioned digital-data-communication networks that would enable real-time acquisition and monitoring of data from geographically distributed sensors. Examples of sensors to be connected to such networks include security cameras, radio-frequency identification units, and geolocation units based on the Global Positioning System. Through suitable software configuration and without changing hardware, these transceivers could be made to operate according to any of a number of complex wireless-communication standards that could be characterized by diverse modulation schemes, bandwidths, and data-handling protocols. The adaptive transceivers would include field-programmable gate arrays (FPGAs) and digital signal-processing hardware. In the receiving path of a transceiver, the incoming signal would be amplified by a low-noise amplifier (LNA). The output spectrum of the LNA would be processed by a band-pass filter operating in the frequency range between 900 MHz and 2.4 GHz. Then a down-converter would translate the signal to a lower frequency range to facilitate analog-to-digital conversion, which would be followed by baseband processing by one or more FPGAs. In the transmitting path, a digital stream would first be converted to an analog signal, which would then be up-converted to a selected frequency band before being applied to a transmitting power amplifier. The aforementioned band-pass filter in the receiving path would be a combination of resonant inductor-and-capacitor filters and switched band-pass filters. The overall combination would implement a switch function designed mathematically to exhibit desired frequency responses and to switch the signal in each frequency band to an analog-to-digital converter appropriate for that band to produce a digital intermediate-frequency signal for digital signal processing.

  13. beta-thalassaemia major hos børn og unge i Danmark

    DEFF Research Database (Denmark)

    Jung, Anne; Main, Katharina Maria; Scheibel, Elma;

    2002-01-01

    INTRODUCTION: Beta-thalassemia major occurs with increasing frequency among Danish children as a result of immigration. The aim of the study was to estimate the occurrence of beta-thalassemia major in Denmark, analyse the treatment and organ functions, and identify areas for an improved treatment...

  14. Application of the collective model to determine the rotation bands and vibrational bands of 152Sm and 152Gd nucleus

    International Nuclear Information System (INIS)

    The research of nuclear reactions is necessary to identify the specific characteristics of nucleus and it is the most effective experimental method up to now. However, in order to explain the properties of nuclear structures, in addition to the study of the nuclear reactions, nuclear structure models to explain experimental dat and its theory must be used. There are many nuclear structure models to solve those properties of nucleus. This paper presents a collective model application to identify some of rotational bands and vibrational bands of 152 Sm and 152Gd nucleus which result from beta decay of 152Eu source the. (author)

  15. Dual frequency launcher for circularly polarized antenna

    Science.gov (United States)

    Chen, Ming H.

    1989-10-01

    A dual frequency antenna feed is formed from a central, circular waveguide connected to the flat boundry of circular, disk-shaped resonant cavity. A second circular waveguide is connected one end of a disk-shaped resonant cavity. Energy of one frequency enters and exits the cavity along the common axis of the waveguides. Energy of the second frequency is introduced to the same resonant cavity by way of a plurality of bandpass filters, also connected to the cavity. This energy enters by way of slots in the cylindrical walls of the cavity. The central circular waveguide is propagating at one frequency but cut off at the second frequency. These bandpass filters are at this pass band for the second frequency, but at the rejection band for the first frequency. Therefore, the isolation between these two input ports are obtained.

  16. Review of wide band-gap semiconductors technology

    Directory of Open Access Journals (Sweden)

    Jin Haiwei

    2016-01-01

    Full Text Available Silicon carbide (SiC and gallium nitride (GaN are typical representative of the wide band-gap semiconductor material, which is also known as third-generation semiconductor materials. Compared with the conventional semiconductor silicon (Si or gallium arsenide (GaAs, wide band-gap semiconductor has the wide band gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology research in various countries. This article describes the research agenda of United States and European in this area, focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing challenge of the wide band-gap technology.

  17. Laboratory Investigation of the Airglow Bands

    Science.gov (United States)

    Drouin, Brian; Yu, Shanshan; Crawford, Timothy J.; Miller, Charles E.; Yee, Jeng-Hwa

    2013-06-01

    We report the first high spectral resolution laboratory measurements of oxygen A-band night glow simulated using a static discharge cell. Our static discharge system reproduces the conditions of the mesospheric oxygen night glow - suggesting O(^1D) + O_2 as the primary source of the emission. Additionally, use of the static cell has enabled us to collect spectra for rare molecular oxygen isotopologues using isotopically enriched samples. The (0,0), (0,1), and (1,1) b-Xvibrational bands were observed with a Bruker 125 HR for all six isotopologues. The (1,2) and (2,2) bands were observed also for the main isotopologue. The frequencies of the observed (0,1) transitions resolved discrepancies in Raman data for (16-17, 17-17, and 17-18), enabling us to improve the vibrational parameterization of the ground electronic state in the global fit of Yu et al. Rotationally resolved intensities were determined for the (0,0), (0,1) and (1,1) bands. The experimental band intensity ratios I(0,0)/I(0,1) = 13.6 and I(0,0)/I(1,1) = 60 are in excellent agreement with the recent mesospheric remote sensing data. S. Yu, C.E. Miller, B.J. Drouin, H.S.P. Müller, J. Chem. Phys. 136, 024304, 2012

  18. Thymosin beta 4 and thymosin beta 10 expression in hepatocellular carcinoma

    Directory of Open Access Journals (Sweden)

    W. Theunissen

    2014-03-01

    Full Text Available Thymosin beta 4 (Tβ4 and thymosin beta 10 (Tβ10 are two members of the beta-thymosin family involved in many cellular processes such as cellular motility, angiogenesis, inflammation, cell survival and wound healing. Recently, a role for beta-thymosins has been proposed in the process of carcinogenesis as both peptides were detected in several types of cancer. The aim of the present study was to investigate the expression pattern of Tβ4 and Tβ10 in hepatocellular carcinoma (HCC. To this end, the expression pattern of both peptides was analyzed in liver samples obtained from 23 subjects diagnosed with HCC. Routinely formalin-fixed and paraffin-embedded liver samples were immunostained by indirect immunohistochemistry with polyclonal antibodies to Tβ4 and Tβ10. Immunoreactivity for Tβ4 and Tβ10 was detected in the liver parenchyma of the surrounding tumor area. Both peptides showed an increase in granular reactivity from the periportal to the periterminal hepatocytes. Regarding HCC, Tβ4 reactivity was detected in 7/23 cases (30% and Tβ10 reactivity in 22/23 (97% cases analyzed, adding HCC to human cancers that express these beta-thymosins. Intriguing finding was seen looking at the reactivity of both peptides in tumor cells infiltrating the surrounding liver. Where Tβ10 showed a strong homogeneous expression, was Tβ4 completely absent in cells undergoing stromal invasion. The current study shows expression of both beta-thymosins in HCC with marked differences in their degree of expression and frequency of immunoreactivity. The higher incidence of Tβ10 expression and its higher reactivity in tumor cells involved in stromal invasion indicate a possible major role for Tβ10 in HCC progression.

  19. Beta-globin gene haplotypes and alpha-thalassemia analysis in Babinga pygmies from Congo-Brazzaville.

    Science.gov (United States)

    Mouélé, R; Bodo, J M; Mpelé, D M; Feingold, J; Galactéros, F

    2000-04-01

    We analyzed beta-globin gene cluster haplotypes and deletional alpha+-thalassemia (-alpha3.7kb) in 54 Babinga pygmy subjects from Congo-Brazzaville. The beta(S)-globin gene frequency was 0.065 and that of the deletional alpha-globin gene (-alpha3.7kb) was 0.29. Eighty-five percent of the beta(S) chromosomes and 13% of the beta(A) chromosomes were associated with the Bantu haplotype, 10% of beta(A) chromosomes with the Senegal haplotype, and the remaining beta chromosomes with atypical haplotypes. None of the chromosomes were of the Benin haplotype. These results are clearly of anthropological and evolutionary interest. They also support earlier observations that alpha+-thalassemia is prevalent at a high frequency in African populations.

  20. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen

    2009-01-01

    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  1. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  2. A Novel Design of Frequency Reconfigurable Antenna for UWB Application

    Science.gov (United States)

    Yang, Xiaolin; Yu, Ziliang; Wu, Zheng; Shen, Huajiao

    2016-09-01

    In this paper, we present a novel frequency reconfigurable antenna which could be easily operate in a single notched-band (WiMAX (3.3-3.6 GHz)) UWB frequency band, another single notched-band (WLAN (5-6 GHz)) UWB frequency band and the dual band-notched UWB frequency band (the stopband covers the WiMAX (3.3-3.6 GHz) and WLAN (5-6 GHz)). The reconfigurability is achieved by changing the states of PIN diodes. The simulated results are in agreement well with the measured results. And the measured patterns are slightly changed with antenna reconfiguration. The proposed antenna is a good candidate for various UWB applications.

  3. Loss of balance during balance beam walking elicits a multifocal theta band electrocortical response.

    Science.gov (United States)

    Sipp, Amy R; Gwin, Joseph T; Makeig, Scott; Ferris, Daniel P

    2013-11-01

    Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4-7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12-30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments.

  4. Micromechanics of shear banding

    Energy Technology Data Exchange (ETDEWEB)

    Gilman, J.J.

    1992-08-01

    Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

  5. The mechanism of growth of the low-frequency East Asia-Pacific teleconnection and the triggering role of tropical intraseasonal oscillation

    Science.gov (United States)

    Wang, Jiabao; Wen, Zhiping; Wu, Renguang; Guo, Yuanyuan; Chen, Zesheng

    2016-06-01

    The East Asia-Pacific (EAP) pattern is a well-known meridional teleconnection over East Asia during boreal summer. In this study, the mechanism for growth of the EAP on intraseasonal timescale is investigated through a vorticity budget. It is found that the beta-effect and high-frequency transient eddies have primary contributions to the growth of the low-frequency EAP. The former leads to a westward shift of disturbances associated with the low-frequency EAP and the latter favors an amplification of disturbances, respectively. The interaction between low-frequency disturbances and zonal flow has a damping effect by dragging disturbances eastward. The impact of boreal summer intraseasonal oscillation (BSISO) on the triggering of the low-frequency EAP is also examined in this study based on observational analysis and a linear model experiment. It is shown that an elongated anomalous convection band located in the vicinity of Philippines associated with the dominant mode of BSISO has a significant impact on the initiation of low-frequency EAP via Rossby wave propagation, whereas anomalous convection located over the North Indian Ocean has a limited impact. Based on the results of present study, the low-frequency EAP could be a self-sustained mode, and the BSISO plays a substantial role in triggering the low-frequency EAP.

  6. Xeroradiography in. beta. -thalassaemia

    Energy Technology Data Exchange (ETDEWEB)

    Scutellari, P.N.; Orzincolo, C.; Tamarozzi, R.

    1985-01-01

    Xeroradiographic investigations of the skull, hand, and elbow were performed on 27 patients with homozygous ..beta..-thalassaemia. The results were compared with plain radiographic examinations. Xeroradiography, because of its technical properties (i.e. edge contrast enhancement and wide latitude), was shown to demonstrate cortical thinning of long bones, swelling of the diploic space in the skull, and reticulated patterns in the elbow better than standard radiography. Moreover, the use of 'positive' mode imaging was shown to have advantages in the study of the skull and extremities.

  7. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    Directory of Open Access Journals (Sweden)

    S. Coco

    2008-01-01

    Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.

  8. Achievement of Narrow-Band CARS Signal by Manipulating Broad-band Laser Spectrum

    International Nuclear Information System (INIS)

    We theoretically demonstrate the achievement of narrow-band coherent anti-Stokes Raman scattering (CARS) signal by manipulating broad-band probe spectrum. The narrowing of the CARS signal depends on the spectrum bandwidth of the probe beam, and thus high-resolution CARS signal for a complicated quantum system can be obtained by the simple spectrum manipulation. Furthermore, the energy-level diagram for the complicated quantum system can also be labelled by measuring the CARS signal at a given frequency. (fundamental areas of phenomenology (including applications))

  9. Parkinson subtype-specific Granger-causal coupling and coherence frequency in the subthalamic area.

    Science.gov (United States)

    Florin, Esther; Pfeifer, Johannes; Visser-Vandewalle, Veerle; Schnitzler, Alfons; Timmermann, Lars

    2016-09-22

    Previous work on Parkinson's disease (PD) has indicated a predominantly afferent coupling between affected arm muscle activity and electrophysiological activity within the subthalamic nucleus (STN). So far, no information is available indicating which frequency components drive the afferent information flow in PD patients. Non-directional coupling e.g. by measuring coherence is primarily established in the beta band as well as at tremor frequency. Based on previous evidence it is likely that different subtypes of the disease are associated with different connectivity patterns. Therefore, we determined coherence and causality between local field potentials (LFPs) in the STN and surface electromyograms (EMGs) from the contralateral arm in 18 akinetic-rigid (AR) PD patients and 8 tremor-dominant (TD) PD patients. During the intraoperative recording, patients were asked to lift their forearm contralateral to the recording side. Significantly more afferent connections were detected for the TD patients for tremor-periods and non-tremor-periods combined as well as for only tremor periods. Within the STN 74% and 63% of the afferent connections are associated with coherence from 4-8Hz and 8-12Hz, respectively. However, when considering only tremor-periods significantly more afferent than efferent connections were associated with coherence from 12 to 20Hz across all recording heights. No difference between efferent and afferent connections is seen in the frequency range from 4 to 12Hz for all recording heights. For the AR patients, no significant difference in afferent and efferent connections within the STN was found for the different frequency bands. Still, for the AR patients dorsal of the STN significantly more afferent than efferent connections were associated with coherence in the frequency range from 12 to 16Hz. These results provide further evidence for the differential pathological oscillations and pathways present in AR and TD Parkinson patients. PMID:27393252

  10. Solid state dielectric screening versus band gap trends and implications

    Science.gov (United States)

    Ravichandran, Ram; Wang, Alan X.; Wager, John F.

    2016-10-01

    High-frequency (optical) and low-frequency (static) dielectric constant versus band gap trends, as well as index of refraction versus band gap trends are plotted for 107 inorganic semiconductors and insulators. These plots are describable via power-law fitting. Dielectric screening trends that emerge from this analysis have important optical and electronic implications. For example, barrier lowering during Schottky emission, phonon-assisted or Fowler-Nordheim tunneling, or Frenkel-Poole emission from a trap is found to be significantly more pronounced with increasing band gap due to a reduction in the optical dielectric constant with increasing band gap. The decrease in the interface state density with increasing band gap is another optical dielectric constant trend. The tendency for a material with a wider band gap to be more difficult to dope is attributed to an increase in the ionization energy of the donor or acceptor dopant, which in turn, depends on the optical dielectric constant and the effective mass. Since the effective mass for holes is almost always larger than that for electrons, p-type doping is more challenging than n-type doping in a wide band gap material. Finally, the polar optical phonon-limited mobility depends critically upon the reciprocal difference of the optical and the static dielectric constant. Consequently, electron and hole mobility tend to decrease with increasing band gap in a polar material.

  11. Frequency spirals

    Science.gov (United States)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-09-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call "frequency spirals." These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  12. Acute stress modulates feedback processing in men and women: differential effects on the feedback-related negativity and theta and beta power.

    Directory of Open Access Journals (Sweden)

    Stella Banis

    Full Text Available Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses.

  13. Double beta decay: present status

    OpenAIRE

    Barabash, A. S.

    2008-01-01

    The present status of double beta decay experiments (including the search for $2\\beta^{+}$, EC$\\beta^{+}$ and ECEC processes) are reviewed. The results of the most sensitive experiments are discussed. Average and recommended half-life values for two-neutrino double beta decay are presented. Conservative upper limits on effective Majorana neutrino mass and the coupling constant of the Majoron to the neutrino are established as $ < 0.75$ eV and $ < 1.9 \\cdot 10^{-4}$, respectively. Proposals fo...

  14. Simultaneous beta and gamma spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  15. APPLICATION OF FREQUENCY DOMAIN TECHNIQUE IN HLS

    Institute of Scientific and Technical Information of China (English)

    Sun Baogen; Qiu Ling

    2002-01-01

    The paper introduce the measurement of some beam parameters for Hefei Light Source (HLS) by frequency domain technique, which include the betatron tune, average beta function, natural chromaticity, corrected chromaticity, and center frequency. Additionally, the measurement of the influence of DC clearing electrodes on the betatron tune shift is also described.Some measurement results are given. The measurement results are compared with the theoretical values and shown to be in good agreement.

  16. APPLICATION OF FREQUENCY DOMAIN TECHNIQUE IN HLS

    Institute of Scientific and Technical Information of China (English)

    SunBaogen; QiuLing

    2002-01-01

    The paper introduce the measurement of some beam parameters for Hefei Light Source(HLS)by frequency domain technique ,which include the betatron tune, average beta function ,natural chromaticity,corrected chromaticity ,and center frequency.Additionally ,the measurement of the influence of DC clearing electrodes on the betatron tune shift is also described.Some measurement results are given .The measurement results are compared with the theoretical values and shoen to be in good agreement.

  17. 47 CFR 25.202 - Frequencies, frequency tolerance and emission limitations.

    Science.gov (United States)

    2010-10-01

    ... GHz 24.65-24.75 GHz (6) The following frequencies are available for use by the Satellite Digital Audio... in the broadcasting-satellite service. 4 This band is shared on an equal basis with the Government... broadcasting-satellite service, and the sub-band 17.7-17.8 GHz is shared coequally with terrestrial...

  18. Dual-Band Optical Bench for Terahertz Radiometer for Outer Planet Atmospheres (TROPA)

    Science.gov (United States)

    Schlecht, Erich; Jamnejad, Vahraz

    2012-01-01

    We have developed a wide-band dual frequency spectrometer for use in deep space planetary atmospheric spectroscopy. The instrument uses a dual-band architecture, both to be able to observe spectral lines from a wide range of atmospheric species, and to allow a higher precision retrieval of temperature/pressure/partial pressure and wind profiles. This dual-band approach requires a new design for the optical bench to couple both frequencies into their respective receivers.

  19. The compact linear antenna array system of the short-wave band consisting of "butterfly" radiators

    OpenAIRE

    Kudzin, Viktor P.; Lozovsky, V. N.; N.I. Shlyk

    2014-01-01

    The broadband linear antenna array system of vertical polarization for a short-wave band operation consisting of "butterfly" radiators is offered. Antenna system consists of two arrays located before each other. Array 1 operates in frequency band 4–8 MHz, array 2 – in band 8–16 MHz. Wire reflector serves for array 1 and the last serves as reflector for array 2. Advantage of antenna system is "planeness" of a design and absence of high-frequency insulators.

  20. Photonic band structure of two-dimensional metal/dielectric photonic crystals

    International Nuclear Information System (INIS)

    An improved plane wave expansion method for the numerical calculation of photonic bands of metal/dielectric photonic crystal (PC) are presented. This method is applied to two-dimensional PCs with frequency-dependent dielectric constants. We obtained the photonic band structure of three kinds of structures: sawtooth, cylinder and hole PCs. The results show that the lowest band-1 is relatively flat, and does not approach zero. Also, there is no complete band-gap that extends throughout the first Brillouin zone for these three structures. However, there are partial band-gaps in different directions in the first Brillouin zone. For the complementary cylinder and hole PCs, their photonic bands are similar except for the lowest three bands; the hole PC’s lowest frequency of band-1 is larger than that of cylinder PC for the configuration R/d  =  0.2. (paper)