Log in

Relevant bibliographies by topics / Phase spectrum / Journal articles

Journal articles on the topic 'Phase spectrum'

To see the other types of publications on this topic, follow the link: Phase spectrum.

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Phase spectrum.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

He, Wei, De Tian, and Wei Long Wang. "Effect of Wind Shear on Rotational Fourier Spectrum of Wind Turbine." Applied Mechanics and Materials 271-272 (December 2012): 872–76. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.872.

Full text

Abstract:

In order to accurately obtain the influence of rotational effect on fluctuating component of turbulent wind acted on wind turbine, considering source spectrum and rotational sample points were changed since wind shear changed mean wind speed in the rotor plane along the vertical direction, rotational Fourier spectrum with wind shear was deduced. Based on the investigation on a 3MW three-bladed pitch regulated wind turbine, rotational Fourier spectrums with and without wind shear were compared, the effect of radius on rotational Fourier spectrum was analyzed, cross power spectral densities of rotational Fourier spectrum with different blades and variable radius were compared. The results show that the effect of wind shear on amplitude of rotational Fourier spectrum is unconspicuous while the phase frequency characteristic is alternative for the sample points are changed. Rotational Fourier spectrum energy removes to the high frequency bands, the amplitudes of peak at the integer multiple rotational frequencies increase with radius increases. The initial phase has little influence to the amplitude of spectrum, and cross power spectral densities of different radius are obviously less than auto power spectral densities of the same radius.

APA, Harvard, Vancouver, ISO, and other styles

2

Huang, Xiang-dong, and Zhao-hua Wang. "Phase Difference Correcting Spectrum Method Based on All-phase Spectrum Analysis." Journal of Electronics & Information Technology 30, no. 2 (February 22, 2011): 293–97. http://dx.doi.org/10.3724/sp.j.1146.2006.00804.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Dwivedi, Vatsal, and Victor Chua. "Phase space entanglement spectrum." Journal of Physics A: Mathematical and Theoretical 51, no. 31 (June 28, 2018): 315304. http://dx.doi.org/10.1088/1751-8121/aacc4d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

He, Wei, De Tian, Qi Li, and Ning Bo Wang. "Rotational Turbulent Wind Field Simulation of Wind Turbine." Applied Mechanics and Materials 291-294 (February 2013): 472–76. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.472.

Full text

Abstract:

In order to accurately obtain the influence of rotational effect on fluctuating component of turbulent wind acted on wind turbine, rotational Fourier spectrum with considering rotational effect of rotor was deduced. Physical nature of the rotational Fourier spectrum embodied by coherence function and phase lag was indicated. Auto power spectral density and cross power spectral density of rotational Fourier spectrum with introducing phase lag were proposed. The spectrum matrix constructed by the module of rotational Fourier spectrum was decomposed with Cholesky's method, according to the spectrum representation method with introducing phase lag, the random turbulent wind speed field was generated by superposing a set of cosine functions. Finally, an example involving simulation of the longitudinal turbulent wind velocity time series of a 1.5 MW three-bladed pitch regulated wind turbine was investigated. The target spectrum and simulated spectrum were compared. The result shows that the proposed algorithm is more accurate to simulate the fluctuating wind velocity of rotational blade.

APA, Harvard, Vancouver, ISO, and other styles

5

Dainty, Anton M., and David B. Harris. "Phase velocity estimation of diffusely scattered waves." Bulletin of the Seismological Society of America 79, no. 4 (August 1, 1989): 1231–50. http://dx.doi.org/10.1785/bssa0790041231.

Full text

Abstract:

Abstract Two methods are investigated for estimating the phase velocity of diffusely scattered seismic waves simultaneously arriving from different azimuths and recorded by a two-dimensional array of seismometers. The Hankel spectrum is the average of the frequency-wavenumber (FK) spectrum over all azimuths, while the wavenumber spectrum is derived by integrating the FK spectrum around a contour of constant phase velocity, i.e., a circle centered on the origin in the wavenumber plane. If the conventional estimate of the FK spectrum using the covariance matrix of the seismometer signals is integrated, a closed form for both the Hankel spectrum and the wavenumber spectrum may be found; the two spectra are very similar, the wavenumber spectrum being equal to the Hankel spectrum times the wavenumber. In spite of this similarity, however, we find that the two formulations have significantly different behavior for small wavenumbers, i.e., high phase velocities. In both cases there is a highest (true) velocity that can be estimated from the spectral maximum for a given array aperture (“velocity cut-off”). The Hankel spectrum estimates too high a velocity; for true wavenumbers below a certain limit, infinite velocity is estimated. The wavenumber spectrum, on the other hand, estimates too low a velocity, and there is an upper limit on the estimated velocity. An example illustrating these difficulties for the two methods is given for teleseismic P coda of an event recorded at the NORESS array in southern Norway: in spite of the problems, the analysis is able to demonstrate that the coda consists of two components; a coherent P-wave component with a high phase velocity and a diffuse S-wave component of low phase velocity. The cut-off and bias problem are investigated by numerical simulation for the NORESS array using azimuthal averaging and synthetic signals. The results confirm and quantify the cut-off problem at low wavenumbers and indicate that wavenumbers estimated from the Hankel and wavenumber spectra maxima bracket the true wavenumber, with the Hankel spectrum estimate being low (phase velocity too high) and the wavenumber spectrum estimate high. The bias of both methods decreases with increasing wavenumber (decreasing phase velocity) and they are both asymptotically unbiased. The wavenumber spectrum has a superior performance at low wavenumbers (high phase velocity), but the Hankel spectrum gives superior results at high wavenumbers (low phase velocity). The product of the linear wavenumber (= 1/wavelength) and the array aperture define “high” and “low” wavenumbers; for low wavenumbers, the product is 1 or less. In an Appendix, we find absolute lower bounds on the cut-offs analytically. The problems could be mitigated by using high resolution methods.

APA, Harvard, Vancouver, ISO, and other styles

6

Hutson, M. Shane, and Mark S. Braiman. "Direct Phase Correction of Differential FT-IR Spectra." Applied Spectroscopy 52, no. 7 (July 1998): 974–84. http://dx.doi.org/10.1366/0003702981944616.

Full text

Abstract:

Step-scan transient Fourier transform infrared (FT-IR) difference spectra are often measured in an ac-coupled configuration. The resulting differential intensity spectra contain both positive and negative bands. This condition poses problems for direct phase correction by the standard Mertz and Forman methods. Restricting the calculated phase angle to the range [–π/2, π/2] was previously shown to fix some of these problems, but we show that the use of a reduced-resolution phase spectrum can produce other artifacts. The effect of reduced resolution is analyzed for a simulated noise-free spectrum and for a measured transient spectrum of a real photochemical system, bacteriorhodopsin. Examination of these results reveals that the Mertz and Mertz Signed methods can produce spectral bands of reduced magnitude and unusual band shape, with considerable amounts of intensity remaining along the imaginary axis after phase correction. However, these errors can be eliminated by self-convolution of the measured interferogram, which doubles all phase angles, prior to smoothing. This procedure removes the potential discontinuities in the phase angle due to sign changes in the differential spectrum. With bacteriorhodopsin, this doubled-angle method for direct phase correction is able to produce a transient spectrum which closely matches that produced by using a separately measured dc interferogram to calculate the phase angle.

APA, Harvard, Vancouver, ISO, and other styles

7

Mohamad, Eizuddin, and Nor Hayati Saad. "Ergonomics Intervention in Indoor Spectrum Measurement Activities." Applied Mechanics and Materials 899 (June 2020): 230–37. http://dx.doi.org/10.4028/www.scientific.net/amm.899.230.

Full text

Abstract:

Engineers in the communication and multimedia industries in Malaysia exposed to the risk factors of work-related musculoskeletal disorders. A comprehensive study was conducted to perform ergonomic studies for indoor spectrum measurement activity to improve productivity and occupational safety and health. The study consisted of two phases, where the participative assessments and direct observations were conducted on 17 engineers. In the first phase, the indoor spectrum measurement problem identification was performed by using the portable and handheld spectrum analyser. The questionnaire, body part assessments and archival operation records were investigated. In the second phase, the ergonomics intervention was introduced with a low-cost trolley that removed the work-related musculoskeletal disorders from the engineers. The same test subject, environments, work procedures and evaluation method in phase one were repeated in phase two. The analysis was done by comparing the findings between both phases through statistical analysis, and the significant improvements of ergonomic interventions were identified. The outcome of the study concluded that the analysis and results meet the main objective.

APA, Harvard, Vancouver, ISO, and other styles

8

Robertson, R. M., J. A. de Haseth, and R. F. Browner. "MAGIC-LC/FT-IR Spectrometry with Buffered Solvent Systems." Applied Spectroscopy 44, no. 1 (January 1990): 8–13. http://dx.doi.org/10.1366/0003702904085886.

Full text

Abstract:

The first demonstration of identifiable infrared (IR) spectra obtained from buffered (volatile and nonvolatile buffers) mobile phases using the Monodisperse Aerosol Generator Interface for Combining Liquid Chromatography with Fourier Transform Infrared (MAGIC-LC/FT-IR) spectrometry is described. Ammonium acetate, a volatile buffer, was used to buffer an 80:20 acetonitrile: water mobile phase to pH 5.0. Caffeine was deposited from this buffered mobile phase, and the spectrum was used as a reference to compare with caffeine spectra obtained from nonvolatile buffered mobile phases. The two nonvolatile buffers used were potassium hydrogen phthalate (KHP) and potassium dihydrogen phosphate (KH2PO4). The KH2PO4 was used to buffer an acetonitrile:water mobile phase and a methanol:water mobile phase, whereas the KHP buffer was used only in a methanoh:water mobile phase. Samples of caffeine were deposited from each of the above buffer systems along with the nonvolatile buffer. Infrared spectra of caffeine were obtained by spectral subtraction of previously stored buffer spectra from the caffeine:buffer spectra. The resulting spectra were identical to a caffeine reference spectrum.

APA, Harvard, Vancouver, ISO, and other styles

9

Sagara, Takamasa, Hidekazu Murase, Masaharu Komatsu, and Naotoshi Nakashima. "Toward the Interpretation of Electroreflectance Spectral Profiles: Hemin Adsorbed on an HOPG Electrode Revisited." Applied Spectroscopy 54, no. 2 (February 2000): 316–23. http://dx.doi.org/10.1366/0003702001949285.

Full text

Abstract:

The features of the potential-modulated UV-visible reflectance (electroreflectance) spectrum at an electrode/solution interface are discussed by comparing experimental and simulated spectra. At a basal plane of a highly oriented pyrolytic graphite (HOPG) electrode covered with a molecular layer of hemin in 0.1 M Na2B4O7 aqueous solution, the electroreflectance signal was confirmed to be proportional to the amount of adsorbed hemin interconverted between oxidized and reduced forms. The electroreflectance spectrum in response to p-polarized incident light depended little on the incident angle, and the spectral profile was different from the difference absorption spectrum between oxidized and reduced hemin in solution phase. The spectral feature of the simulated electroreflectance spectrum with the use of Fresnel equations for a stratified three-phase optical model with a thin-layer approximation was markedly different from the experimental spectrum in regard to spectral profile and incident angle dependence. These results may suggest that refinement of the optical model to predict the reflectance spectrum at an electrode surface covered with a molecular layer is necessary for the interpretation of electroreflectance spectral profiles.

APA, Harvard, Vancouver, ISO, and other styles

10

HUANG, YUNXIA, SHUWU XU, and XIAOHUA YANG. "HIGH-RESOLUTION PHOTOELECTRON SPECTROSCOPY BY SPECTRAL PHASE STEP MODULATION." Journal of Nonlinear Optical Physics & Materials 22, no. 04 (December 2013): 1350045. http://dx.doi.org/10.1142/s0218863513500458.

Full text

Abstract:

Femtosecond-induced resonance-enhanced multi-photon ionization photoelectron spectroscopy (REMPI-PES) has the drawback of low spectral resolution due to broadband spectrum of the laser. In this paper, we theoretically demonstrate that high-resolution REMPI-PES can be achieved by shaping the femtosecond laser pulse with spectral phase step modulation. Our results show that, by manipulating the phase step position and the modulation depth, a narrowband peak or hole in the photoelectron spectrum can be observed, and the position of the narrowband peak or hole is correlated with the eigenenergy of the excite state. Therefore, both high-resolution REMPI-PES and the excited state structure can be obtained by observing the narrowband peaks or holes.

APA, Harvard, Vancouver, ISO, and other styles

11

Pospelov, Boris, Evgenіy Rybka, Mikhail Samoilov, Ihor Morozov, Yuliia Bezuhla, Tetiana Butenko, Yuliia Mykhailovska, Oleksandr Bondarenko, and Julia Veretennikova. "Defining the features of amplitude and phase spectra of dangerous factors of gas medium during the ignition of materials in the premises." Eastern-European Journal of Enterprise Technologies 2, no. 10 (116) (April 30, 2022): 57–65. http://dx.doi.org/10.15587/1729-4061.2022.254500.

Full text

Abstract:

This paper theoretically substantiates research into the spectral features of the dynamics of the main dangerous parameters of a gas environment when igniting materials in a laboratory chamber. Studying such spectral features is based on the calculation of the direct discrete Fourier transform for discrete measurements, equal in number, over the current intervals of observation of the hazardous examined parameter of the gas medium before and after the material is ignited. In this approach, a Fourier discrete transform makes it possible to determine the instantaneous amplitude and phase spectra for the time intervals under consideration. This makes it possible to explore the peculiarities of the distribution of amplitudes and phases of harmonic components in the spectrum of the dynamics of dangerous parameters of the gas environment before and after the ignition of materials. The results of experimental studies established that the nature of the amplitude spectrum is low-informative and not sensitive enough to fires. The main contribution to the amplitude spectrum of the dynamics of the investigated hazardous parameters of the gas environment in the chamber is made by the frequency components in the range of 0–0.2 Hz. The contribution to the amplitude spectrum of frequency components over 0.2 Hz is insignificant and decreases with increasing frequency. It is established that from the phase spectrum, the nature of the random scattering of phases for frequency components exceeding 0.2 Hz is informative. It was found that the nature of the phase spread for these frequency components in the spectrum depends on the type of ignition material. The results reported here could prove useful when devising new effective technologies for detecting fires in the premises of objects in various fields to protect against fires. This is explained by the fact that for the detection of fires in the premises, high-frequency components are important, characterized by the increase in dangerous parameters of the gas environment

APA, Harvard, Vancouver, ISO, and other styles

12

Morita, Shigeaki, Masaru Tanaka, Isao Noda, and Yukihiro Ozaki. "Phase Angle Description of Perturbation Correlation Analysis and its Application to Time-Resolved Infrared Spectra." Applied Spectroscopy 61, no. 8 (August 2007): 867–72. http://dx.doi.org/10.1366/000370207781540051.

Full text

Abstract:

A method of spectral analysis, phase angle description of perturbation correlation analysis, is proposed. This method is based on global phase angle description of generalized two-dimensional (2D) correlation spectroscopy, proposed by Shin-ichi Morita et al., and perturbation-correlation moving-window 2D (PCMW2D) correlation spectroscopy, proposed by Shigeaki Morita et al. For a spectral data set collected under an external perturbation, such as time-resolved infrared spectra, this method provides only one phase angle spectrum. A phase angle of the Fourier frequency domain correlation between a spectral intensity (e.g., absorbance) variation and a perturbation variation (e.g., scores of the first principle component) as a function of spectral variable (e.g., wavenumber) is plotted. Therefore, a degree of time lag of each band variation with respect to the perturbation variation is directly visualized in the phase angle spectrum. This method is applied to time-resolved infrared spectra in the O–H stretching region of the water sorption process into a poly(2-methoxyethyl acrylate) (PMEA) film. The time-resolved infrared (IR) spectra show three broad and overlapping bands in the region. Each band increases toward saturated water sorption with different relaxation times. In comparison to conventional methods of generalized 2D correlation spectroscopy and global phase angle mapping, the method proposed in the present study enables the easier visualization of the sequence as a degree of phase angle in the spectrum.

APA, Harvard, Vancouver, ISO, and other styles

13

CHEN YANG, LU QING-ZHENG, MA XING-XIAO, GUI ZHI-FENG, ZHAO XIAN-ZHANG, and LU TONG-XING. "EMISSION SPECTRUM OF GAS PHASE CCl2." Acta Physica Sinica 41, no. 10 (1992): 1582. http://dx.doi.org/10.7498/aps.41.1582.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Jia Fangxiu, 贾方秀, 丁振良 Ding Zhenliang, 袁峰 Yuan Feng, and 葛东升 Ge Dongsheng. "All-Phase Fourier Transfrorm Spectrum Analysis." Acta Optica Sinica 30, no. 10 (2010): 2928–34. http://dx.doi.org/10.3788/aos20103010.2928.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Lorenzi, Christian, Frédéric Berthommier, and Laurent Demany. "Discrimination of amplitude-modulation phase spectrum." Journal of the Acoustical Society of America 105, no. 5 (May 1999): 2987–90. http://dx.doi.org/10.1121/1.426911.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Friel, J. J., and R. Batcheler. "Automatic Phase Segmentation of Spectrum Images." Microscopy and Microanalysis 8, S02 (August 2002): 350–51. http://dx.doi.org/10.1017/s1431927602101267.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Read, W. Wayne, and Rodney J. Sobey. "Phase Spectrum of Surface Gravity Waves." Journal of Waterway, Port, Coastal, and Ocean Engineering 113, no. 5 (September 1987): 507–21. http://dx.doi.org/10.1061/(asce)0733-950x(1987)113:5(507).

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Casagrande, F., A. Ferraro, A. Lulli, R. Bonifacio, E. Solano, and H. Walther. "Micromaser spectrum and phase diffusion dynamics." Journal of Optics B: Quantum and Semiclassical Optics 5, no. 4 (August 1, 2003): S459—S466. http://dx.doi.org/10.1088/1464-4266/5/4/351.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Qi-Jin Chen and Xu-Jian Guan. "Spectrum analysis of phase amplitude modulation." IEEE Transactions on Broadcasting 36, no. 1 (March 1990): 34–36. http://dx.doi.org/10.1109/11.52362.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Choi, Byoung-Koo, H. J. Labbé, and D. J. Lockwood. "Raman spectrum of Na2SO4 (phase III)." Solid State Communications 74, no. 2 (April 1990): 109–13. http://dx.doi.org/10.1016/0038-1098(90)90615-i.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Choi, Byoung-Koo, and D. J. Lockwood. "Raman spectrum of Na2SO4 (phase V)." Solid State Communications 72, no. 1 (October 1989): 133–37. http://dx.doi.org/10.1016/0038-1098(89)90893-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Soininen, Heikki. "The behavior of the apparent resistivity phase spectrum in the case of two polarizable media." GEOPHYSICS 50, no. 5 (May 1985): 810–19. http://dx.doi.org/10.1190/1.1441955.

Full text

Abstract:

I employed numerical modeling to examine the formation of the apparent resistivity phase spectrum first of a polarizable prism situated in a polarizable half‐space, and second of two polarizable prisms joined in an unpolarizable half‐space. The calculations were done using the integral equation technique. The frequency dependence of the resistivity of the polarizable medium is depicted by means of the Cole‐Cole dispersion model. The effect of a weakly polarizable half‐space may be handled by simply adding the phase angle of the half‐space to the apparent phase due to the body. The apparent spectral parameters can be inverted by fitting the sum of two Cole‐Cole dispersion model phase spectra to the apparent phase spectrum. Of the parameters describing the prism, the apparent chargeability is smaller than the chargeability of the original petrophysical spectrum because of geometric attenuation. The apparent frequency dependence, on the other hand, is very close to the value of the original frequency dependence. The apparent time constant is commonly also near the true time constant of the petrophysical spectrum. The values of the apparent spectral parameters of the polarizable half‐space are all close to their petrophysical or true values. The apparent spectrum of two polarizable prisms builds up in a complex fashion. Nevertheless, by measuring the spectra at a number of points along a profile crossing over two formations differing in time constant, the various components can be discriminated from the apparent spectrum even if the difference in time constant is small. As the conductivity contrast decreases, the share of the spectrum of the formation in the apparent spectrum increases. Similarly, the formation with the smaller time constant is in a more advantageous position than the body with the greater time constant.

APA, Harvard, Vancouver, ISO, and other styles

23

Angrisani, Leopoldo, Domenico Capriglione, Gianni Cerro, Luigi Ferrigno, and Gianfranco Miele. "On Employing a Savitzky-Golay Filtering Stage to Improve Performance of Spectrum Sensing in CR Applications Concerning VDSA Approach." Metrology and Measurement Systems 23, no. 2 (June 1, 2016): 295–308. http://dx.doi.org/10.1515/mms-2016-0019.

Full text

Abstract:

Abstract In this paper, a filtering stage based on employing a Savitzky-Golay (SG) filter is proposed to be used in the spectrum sensing phase of a Cognitive Radio (CR) communication paradigm for Vehicular Dynamic Spectrum Access (VDSA). It is used to smooth the acquired spectra, which constitute the input for a spectrum sensing algorithm. The sensing phase is necessary, since VDSA is based on an opportunistic approach to the spectral resource, and the opportunities are represented by the user-free spectrum zones, to be detected through the sensing phase. Each filter typology presents peculiarities in terms of its computational cost, de-noising ability and signal shape reconstruction. The SG filtering properties are compared with those of the linear Moving Average (MA) filter, widely used in the CR framework. Important improvements are proposed.

APA, Harvard, Vancouver, ISO, and other styles

24

Yu Rong, 余荣, and 江月松 Jiang Yuesong. "Photoacoustic Spectroscopy System with Amplitude Spectrum and Phase Spectrum Measurement Functions." Acta Optica Sinica 34, no. 2 (2014): 0230001. http://dx.doi.org/10.3788/aos201434.0230001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Zhao, Feng-Xin, and Yu-Xian Hu. "The relation between the response spectrum and the phase difference spectrum." Acta Seismologica Sinica 9, no. 3 (August 1996): 371–76. http://dx.doi.org/10.1007/bf02650972.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Hargreaves, Neil D. "Air‐gun signatures and the minimum‐phase assumption." GEOPHYSICS 57, no. 2 (February 1992): 263–71. http://dx.doi.org/10.1190/1.1443239.

Full text

Abstract:

The air‐gun array signature is close to minimum‐phase as a function of continuous time, in the sense that for processing purposes its phase spectrum can be derived from the Hilbert transform of the logarithm of its amplitude spectrum. This phase spectrum is different, however, from the minimum‐phase spectrum that is estimated by spiking deconvolution for a sampled and time‐windowed version of the signature. As a consequence, there can be large phase errors when spiking deconvolution is applied to an air‐gun signature or to a recording instrument response. The errors can be shown to consist primarily of a time shift and, at least visually over a limited bandwidth, a phase rotation of the output wavelet. The time shift is introduced by time sampling, while the phase rotation is caused by the spectral smoothing generated by time windowing. If the seismic wavelet as a whole, and not just the air‐gun signature, is minimum‐phase, then the total residual phase error after spiking deconvolution, including also the error due to data noise, can also be shown to be close to a time shift and a phase rotation. This may be physical justification for the phase rotation schemes that are often successful in matching seismic data and well‐log synthetics. The minimum‐phase assumption can be used for statistical air‐gun array signature deconvolution, providing that a limited amount of deterministic information (the instrument slopes and the source and receiver depths in the approach used here) is available to guide the process in those areas of the spectrum that are critical to the phase computation. Date examples show that, with care, almost identical results can then be obtained from either purely statistical deconvolution or deterministic deconvolution plus statistical deconvolution of multiples and ghosting.

APA, Harvard, Vancouver, ISO, and other styles

27

Simmons, James A., and Andrea M. Simmons. "Cognitive perception of biosonar echo delay, phase, and spectrum." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A93. http://dx.doi.org/10.1121/10.0018276.

Full text

Abstract:

FM echolocating big brown bats combine the acoustic delay, phase, and spectrum of echoes into a unitary cognitive attribute of perceived delay. In this talk, we will present psychophysical, neurophysiological, and modeling data showing how this might be accomplished. Delay accuracy measured psychophysically approximates coherent matched-filter accuracy. Psychophysical curves of echo-delay resemble pulse-echo crosscorrelation functions, with phase manifested directly within 20 μs. Computational modeling shows that low-pass time-frequency bandpass filtering at 10 kHz enables the contribution from phase. Neural responses from the auditory midbrain are phase-sensitive for tone-burst offsets up to15 kHz. Echo spectrum (spectral nulls and ripples) is transformed into psychophysical percepts of delay. The external-ear spectral null creates an elevation-dependent peak at about 35 μs for vertical target tracking. Off-axis clutter masking is suppressed by a Gestalt-like normalization process that operates within delay percepts. The organization of perceived delay and the appearance of phase shifts is facilitated by delay processing that begins at the low-frequency tail end of FM sweeps and the linking of 1st and 2nd harmonic frequencies. Surprisingly, this result requires the entire echo to be received before any delay is determined. The implications of this result will be discussed. [Work supported by ONR.]

APA, Harvard, Vancouver, ISO, and other styles

28

Suhara, Masahiko, and Koichi Mano. "NQR and Phase Transitions in Hexachlorocyclopropane Crystal." Zeitschrift für Naturforschung A 45, no. 3-4 (April 1, 1990): 339–42. http://dx.doi.org/10.1515/zna-1990-3-421.

Full text

Abstract:

Abstract35Cl NQR and DSC studies on phase transitions in hexachlorocyclopropane (HCCP), C3Cl6 , are reported. It is found that HCCP has three solid phases: A high temperature disordered phase (Phase I) above 301 K (no NQR spectrum was observed); a metastable phase (Phase II), which exhibited 6 NQR lines from 77 to 270 K; a low temperature phase (Phase III) in which a 24-multiplet of 35Cl NQR lines at 77 K, the most complex multiplet spectrum ever reported was observed. DSC measurement shows a A-type transition at 301 K and a broad transition of very slow rate at 285 K. The structure and mechanism of phase transitions in HCCP crystal are discussed.

APA, Harvard, Vancouver, ISO, and other styles

29

Satyanarayana, D., and Abdullah Said Alkalbani. "A Spectrum Sensing Method for TDM based Cognitive Radio Networks." International Journal of Engineering & Technology 7, no. 4.1 (September 12, 2018): 124. http://dx.doi.org/10.14419/ijet.v7i4.1.28239.

Full text

Abstract:

The usage of mobile radio devices has been increased exponentially for the last few years and the radio spectrum is being exhausted every day. Hence, there is huge demand for new methods and technologies for solving the radio spectrum scarcity. On this line, the researchers invented a new technology called Cognitive Radio Networks (CRN). There are two phases associated with the CRN. The first phase handles the spectrum hole detection and the second phase allocates the spectrum hole. In this paper, we propose a new method for spectrum hole detection in time division multiplexing (TDM) based communications systems. The simulation work shows that the proposed method is useful for solving the spectrum scarcity problems in TDM based systems.

APA, Harvard, Vancouver, ISO, and other styles

30

Chen, Hong-xi, Qin Zhang, Zhi-yun Lian, Ju Liu, Zi-yan Shi, Xiao-hui Miao, Hui-ru Feng, et al. "Muscle damage in patients with neuromyelitis optica spectrum disorder." Neurology - Neuroimmunology Neuroinflammation 4, no. 6 (September 14, 2017): e400. http://dx.doi.org/10.1212/nxi.0000000000000400.

Full text

Abstract:

Objective:Increasing evidence has shown that skeletal muscle damage plays a role in neuromyelitis optica spectrum disorder (NMOSD). The objective of this study was to compare the serum creatine kinase (sCK) levels in NMOSD patients with different clinical statuses.Methods:In the observational study, levels of sCK were measured during the acute and stable phases for patients with NMOSD and healthy controls (HCs).Results:We enrolled 168 patients with NMOSD (female:male ratio, 153:15; age: 43.9 ± 13.1 years) in the acute phase, and blood samples were collected from 85 of the patients with NMOSD during both acute and stable phases to determine the sCK levels. The mean log sCK levels of the patients with NMOSD in the acute phase were higher (4.51 ± 1.17, n = 85) than those of the patients with NMOSD in the stable phase (3.85 ± 0.81, n = 85, p = 0.000). Furthermore, the log sCK levels of the patients with NMOSD in the stable phase were lower than those of the HCs (4.31 ± 0.39, n = 200, p = 0.000). In patients with sCK levels within the normal limits, these differences were also observed (p < 0.05). In the multivariable linear regression model performed for the patients with NMOSD in the acute phase, it suggested that a higher estimated glomerular filtration rate (p = 0.026), patients with the core clinical characteristics of optic neuritis (p = 0.005), and serum anti-SSA positivity (p = 0.019) predicted lower log sCK levels.Conclusions:Muscle damage occurs in patients with NMOSD and is aggravated during the acute phase.

APA, Harvard, Vancouver, ISO, and other styles

31

Chi, Zimeng, Xiaoyong Guo, Zaijun Wang, and Qiang Zheng. "Topological phase transitions of three-dimensional topological insulator without energy gap closing." International Journal of Modern Physics B 29, no. 28 (October 29, 2015): 1550199. http://dx.doi.org/10.1142/s0217979215501994.

Full text

Abstract:

In this paper, we demonstrate an anomalous topological phase transition without closing of bulk energy gap. We find such an effect in a model of three-dimensional (3D) topological insulator (TI) subjected to the in-plane exchange field. The energy spectrum, spin spectrum and momentum-dependent spin Chern numbers are calculated. It is shown that our system realizes both the 3D TI phase and the integer quantum Hall (QH) phase. By varying the strength of exchange field, a series of topological phase transitions takes place and in the mean time the energy gap remains open. However, the spin spectrum is closed at the transition and various topological phases are characterized with different number of nodes in spin spectrum. In a tight-binding form, the surface modes are discussed to confirm with the phase diagram. Particularly for a strong field, we find the flat band edge modes which may provide an opportunity for realizing the two-dimensional (2D) fractional QH effect on the boundary of our 3D system.

APA, Harvard, Vancouver, ISO, and other styles

32

Marla, Vinay, Ashish Shrestha, Khushboo Goel, and Sajeev Shrestha. "The Histopathological Spectrum of Pyogenic Granuloma: A Case Series." Case Reports in Dentistry 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/1323798.

Full text

Abstract:

Background.Pyogenic granuloma is a reactive tumor-like lesion commonly affecting the oral cavity. These lesions usually appear as localized solitary nodule with a sessile or pedunculated base and colour varying from red, purplish, or pink, depending on the vascularity of the lesion. Pyogenic granuloma shows predilection for gingiva and is usually slow growing, but at times it shows rapid growth. The natural course of this lesion can be categorized into three distinct phases, namely, (i) cellular phase, (ii) capillary phase/vascular phase, and (iii) involutionary phase. Histopathologically, pyogenic granuloma is classified into lobular capillary hemangioma (LCH) and non-lobular capillary hemangioma (non-LCH).Case Presentation. In this series, four cases (varied age groups and both genders) of pyogenic granuloma showing varying histopathological presentation in relation to its clinical course have been described. The lesion in its early phase reveals diffuse endothelial cells, with few budding into capillaries. Among the capillary phase, the LCH type shows numerous blood vessels organized into lobular aggregates whereas the non-LCH type does not show any such organization and resembles granulation tissue. The involutionary phase shows healing of the lesion and is characterized by extensive fibrosis in the connective tissue.Conclusion.In conclusion, knowledge of the various histopathological presentation of this lesion is necessary for proper identification.

APA, Harvard, Vancouver, ISO, and other styles

33

Shvets, Petr, Ksenia Maksimova, and Alexander Goikhman. "Raman Spectroscopy of V4O7 Films." Coatings 12, no. 3 (February 22, 2022): 291. http://dx.doi.org/10.3390/coatings12030291.

Full text

Abstract:

A thin film of vanadium oxide Magnéli phase V4O7 was produced using cathodic arc sputtering. X-ray diffraction, Rutherford backscattering spectrometry and Raman investigations confirmed the formation of this phase. The Raman spectrum of V4O7 differs considerably from the spectrum of another Magnéli oxide, V3O5, showing that Raman spectroscopy is an excellent tool for distinguishing between these two phases. Temperature-dependent Raman measurements revealed a significant change of the spectra near the V4O7 metal–insulator phase transition.

APA, Harvard, Vancouver, ISO, and other styles

34

Oleinik, Phelype Haron, Gabriel Pereira Tavares, Bianca Neves Machado, and Liércio André Isoldi. "Transformation of Water Wave Spectra into Time Series of Surface Elevation." Earth 2, no. 4 (November 22, 2021): 997–1005. http://dx.doi.org/10.3390/earth2040059.

Full text

Abstract:

Spectral wave modelling is widely used to simulate large-scale wind–wave processes due to its low computation cost and relatively simpler formulation, in comparison to phase-resolving or hydrodynamic models. However, some applications require a time-domain representation of sea waves. This article proposes a methodology to transform the wave spectrum into a time series of water surface elevation for applications that require a time-domain representation of ocean waves. The proposed method uses a generated phase spectrum and the inverse Fourier transform to turn the wave spectrum into a time series of water surface elevation. The consistency of the methodology is then verified. The results show that it is capable of correctly transforming the wave spectrum, and the significant wave height of the resulting time series is within 5% of that of the input spectrum.

APA, Harvard, Vancouver, ISO, and other styles

35

Deng, Yuqiang, Zubin Wu, Shiying Cao, Lu Chai, Ching-yue Wang, and Zhigang Zhang. "Spectral phase extraction from spectral shearing interferogram for structured spectrum of femtosecond optical pulses." Optics Communications 268, no. 1 (December 2006): 1–6. http://dx.doi.org/10.1016/j.optcom.2006.06.080.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Dai, Yan, Zhang Yin Pu, and Huan Wang. "An Improved FFT Discrete Spectrum Correction and Weighted Alogrithm." Advanced Materials Research 433-440 (January 2012): 3718–23. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.3718.

Full text

Abstract:

For the problem of spectrum correction in phase difference method, a weighed correction method starting from phase difference of secondary largest value is presented in this paper. By the analysis on correction error of maximum and the second largest value in phase difference method, It determines the maximum correction error and the second largest value and conducts error correction method of weighted joint calibration. In addition, it makes analysis on variance for correction result. Finally, the experimental result shows that the method can greatly improve spectral resolution than conventional phase difference method.

APA, Harvard, Vancouver, ISO, and other styles

37

Sun, Chaochao, Peizhong Lu, and Kai Cao. "Phase-Rotated Spectral Correlation Detection for Spectrum Sensing at Low SNR Regimes." IEEE Signal Processing Letters 26, no. 7 (July 2019): 991–95. http://dx.doi.org/10.1109/lsp.2019.2917046.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Shaver, Jeremy M., and Linda B. McGown. "Generation of a New Spectral Format, the Lifetime Synchronous Spectrum (LiSS), Using Phase-Resolved Fluorescence Spectroscopy." Applied Spectroscopy 48, no. 6 (June 1994): 755–60. http://dx.doi.org/10.1366/000370294774369018.

Full text

Abstract:

A new fluorescence spectral format is introduced in which fluorescence lifetime is shown as a function of synchronously scanned wavelength to generate a Lifetime Synchronous Spectrum (LiSS). Lifetimes are determined in the frequency domain with the use of Phase-Resolved Fluorescence Spectroscopy (PRFS) to obtain the phase of the fluorescence signal. Theory and construction of the LiSS are presented and experimental results are shown for solutions of single components and simple binary and ternary mixtures. These results show how the lifetime information in the LiSS augments the steady-state intensity information of a standard synchronous spectrum, providing unique information for identification of components and resolution of overlapping spectral peaks. The LiSS technique takes advantage of noise reduction inherent in the extraction of lifetime from PRFS in addition to standard spectral smoothing techniques. The precision of phase determination through PRFS is found to be comparable to that of direct phase measurements at normal fluorescence intensities and superior for low-intensity signals.

APA, Harvard, Vancouver, ISO, and other styles

39

López-Aguilar, F. "Spectrum and phase transitions in Kondo lattices." Physical Review B 62, no. 1 (July 1, 2000): 415–24. http://dx.doi.org/10.1103/physrevb.62.415.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Takagi, Takeo. "NMR Spectrum of Superfluid3He A-Phase Droplet." Journal of the Physical Society of Japan 66, no. 9 (September 15, 1997): 2741–46. http://dx.doi.org/10.1143/jpsj.66.2741.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Kang, Li, and Nidal Chamoun. "Hydrogen Atom Spectrum in Noncommutative Phase Space." Chinese Physics Letters 23, no. 5 (April 28, 2006): 1122–23. http://dx.doi.org/10.1088/0256-307x/23/5/016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Sheft, Stanley, and William A. Yost. "Discriminating change in the envelope phase spectrum." Journal of the Acoustical Society of America 111, no. 5 (2002): 2468. http://dx.doi.org/10.1121/1.4778532.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Apetrei, Cristina, Hongbin Ding, and John P. Maier. "Gas phase electronic spectrum of linear AlCCH." Physical Chemistry Chemical Physics 9, no. 29 (2007): 3897. http://dx.doi.org/10.1039/b706384a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Tkacz-Śmiech, Katarzyna, Andrzej Koleżyński, and Witold Jastrzebski. "Phase Transitions in BaTiO3from IR Autocorrelation Spectrum." Ferroelectrics 315, no. 1 (June 2005): 73–81. http://dx.doi.org/10.1080/00150190590933014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Buscemi, Isabella Chiara, and Steve Guyot. "Phase spectrum increments of the speckle pattern." European Physical Journal Applied Physics 63, no. 3 (September 2013): 30502. http://dx.doi.org/10.1051/epjap/2013130087.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Chumlea, W. M. Cameron, Shumei S. Guo, and Roger M. Siervogel. "Phase angle spectrum analysis and body water." Applied Radiation and Isotopes 49, no. 5-6 (May 1998): 489–91. http://dx.doi.org/10.1016/s0969-8043(97)00178-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Achkasova, Elena, Mitsunori Araki, Alexey Denisov, and John P. Maier. "Gas phase electronic spectrum of propadienylidene C3H2." Journal of Molecular Spectroscopy 237, no. 1 (May 2006): 70–75. http://dx.doi.org/10.1016/j.jms.2006.02.013.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Stanton, John F., Bradley A. Flowers, Devin A. Matthews, Asa F. Ware, and G. Barney Ellison. "Gas-phase infrared spectrum of methyl nitrate." Journal of Molecular Spectroscopy 251, no. 1-2 (September 2008): 384–93. http://dx.doi.org/10.1016/j.jms.2008.03.026.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Du, H., J. W. Fang, and J. J. Zheng. "Photoacoustic phase spectrum of a layered sample." Applied Physics A: Materials Science & Processing 60, no. 4 (March 1, 1995): 419–23. http://dx.doi.org/10.1007/s003390050122.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Charnotskii, Mikhail. "Sparse spectrum model for a turbulent phase." Journal of the Optical Society of America A 30, no. 3 (February 22, 2013): 479. http://dx.doi.org/10.1364/josaa.30.000479.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!