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Letteratura scientifica selezionata sul tema "Spectrum analysis"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 luglio 2024

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Articoli di riviste sul tema "Spectrum analysis"

1

Zhang, Lian Shun, e Ai Juan Shi. "Classification of Biological Spectrum Based on Principal Component Cluster Analysis". Advanced Materials Research 605-607 (dicembre 2012): 2245–48. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.2245.

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Spectrums of 17 biological tissue phantoms were measured using the fiber-optic spectrometer. Then, the spectrum was preprocessed by multiplicative scatter correction method to devoice the spectrum. Afterwards the features of the spectrum were extracted via principal component analysis. Ultimately, we applied cluster analysis for the spectral features. The results showed that the accumulated credibility of the first 12 spectral principal components was 99.86% for the spectrum after preprocessing; indicating that this spectrum feature extraction might be done in the case of losing no key information. And the results showed that the 17 biological tissue phantoms can be divided into four main categories according their optical features.

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2

Cokelaer, Thomas, e Juergen Hasch. "'Spectrum': Spectral Analysis in Python". Journal of Open Source Software 2, n. 18 (27 ottobre 2017): 348. http://dx.doi.org/10.21105/joss.00348.

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3

Harrar, Khaled, e Mohamed Khider. "Texture Analysis Using Multifractal Spectrum". International Journal of Modeling and Optimization 4, n. 4 (agosto 2014): 336–41. http://dx.doi.org/10.7763/ijmo.2014.v4.396.

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4

Charleston, M. A. "Spectrum: spectral analysis of phylogenetic data". Bioinformatics 14, n. 1 (1 febbraio 1998): 98–99. http://dx.doi.org/10.1093/bioinformatics/14.1.98.

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5

Bujunuru, Anitha, e Srinivasulu Tadisetty. "Performance Analysis of Spectrum Sensing Techniques". Journal of Advanced Research in Dynamical and Control Systems 11, n. 0009-SPECIAL ISSUE (25 settembre 2019): 355–61. http://dx.doi.org/10.5373/jardcs/v11/20192579.

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6

Long, Junbo, Haibin Wang e Peng Li. "Applications of Fractional Lower Order Frequency Spectrum Technologies to Bearing Fault Analysis". Mathematical Problems in Engineering 2019 (27 agosto 2019): 1–24. http://dx.doi.org/10.1155/2019/7641383.

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The traditional spectral analysis method is used to study the characteristics of bearing fault signals in frequency domain, which is reasonable and effective in general cases. However, it is proved that the fault signals have heavy tails in this paper, which are α stable distribution, and 1<α<2, and even the noises belong to α stable distribution. Then the conventional spectral analysis methods degenerate and even fail under α stable distribution environment. Several improved frequency spectral analysis methods are proposed employing fractional lower order covariation or fractional lower order covariance in this paper, including fractional lower order Blackman-Tukey covariation spectrum (FLOBTCS), fractional lower order periodogram covariation spectrum (FLOPCS), and fractional lower order welch covariation spectrum (FLOWCS). In order to suppress side lobe and improve resolution, we present novel fractional lower order autoregression (FLO-AR) and fractional lower order autoregressive moving average (FLO-ARMA) parameter model frequency spectrum methods, and the calculation steps are summarized. The proposed spectrum methods are compared with the existing methods based on second-order statistics under Gaussian and SαS distribution environments, and the results show that the new algorithms have better performance than the traditional methods. Finally, the improved methods are applied to estimate frequency spectrums of the normal and outer race fault signals, and it is demonstrated that they are effective for fault diagnosis.

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Dobigeon, Nicolas, e Nathalie Brun. "Spectral mixture analysis of EELS spectrum-images". Ultramicroscopy 120 (settembre 2012): 25–34. http://dx.doi.org/10.1016/j.ultramic.2012.05.006.

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Chu, Jifeng, Fang-Fang Liao, Stefan Siegmund, Yonghui Xia e Hailong Zhu. "Nonuniform dichotomy spectrum and reducibility for nonautonomous difference equations". Advances in Nonlinear Analysis 11, n. 1 (24 luglio 2021): 369–84. http://dx.doi.org/10.1515/anona-2020-0198.

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Abstract For nonautonomous linear difference equations, we introduce the notion of the so-called nonuniform dichotomy spectrum and prove a spectral theorem. As an application of the spectral theorem, we prove a reducibility result.

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Pedersen, Steen. "Spectral Sets Whose Spectrum Is a Lattice with a Base". Journal of Functional Analysis 141, n. 2 (novembre 1996): 496–509. http://dx.doi.org/10.1006/jfan.1996.0139.

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Arutyunyan, Rafael, Yuri Obukhov e Petr Vabishchevich. "NUMERICAL SIMULATION OF CHARGED FULLERENE SPECTRUM". Mathematical Modelling and Analysis 24, n. 2 (18 marzo 2019): 263–75. http://dx.doi.org/10.3846/mma.2019.017.

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The mathematical model of the electron spectrum of a charged fullerene is constructed on the basis of the potential of a charged sphere and the spherically symmetric potential of an uncharged fullerene. The electron spectrum is defined as the solution of the spectral problem for the one-dimensional Schr\"odinger equation. For the numerical solution of the spectral problem, piecewise-linear finite elements are used. The computational algorithm was tested on the analytical solution of the problem of the spectrum of the hydrogen atom. For solution of matrix spectral problems, a free library for solving spectral problems of SLEPc is used. The results of calculations of the electron spectrum of a charged fullerene C60 are presented.

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Tesi sul tema "Spectrum analysis"

1

Dahl, Jason F. "Time Aliasing Methods of Spectrum Estimation". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd157.pdf.

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鄧愛紅 e Aihong Deng. "Some studies towards improving positron lifetime spectroscopy for semiconductors". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31214083.

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Bing, Zhou. "Crosshole resistivity and acoustic velocity imaging : S.5-D helmholtz equation modeling and inversion /". Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phb613.pdf.

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Chan, Chun-yu. "Mass spectrometric analysis of selected glycoproteins". Thesis, Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B3147942X.

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Tadros-Attalla, Helen. "Power spectrum analysis of redshift surveys". Thesis, University of Oxford, 1996. https://ora.ox.ac.uk/objects/uuid:5a5786db-748e-4c78-bab8-c89a4eda2f07.

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This thesis describes a study of the clustering properties of galaxies and clusters of galaxies as measured by the power spectrum (P(k)) and the counts in cells statistic. The samples used are the optical Stromlo-APM galaxy survey, the APM cluster survey and the IRAS 1.2Jy, QDOT and PSCz surveys. Throughout, N-body simulations, for a variety of cosmological models, are used to test methods and to supplement analytic error estimates. For the Stromlo-APM sample the amplitude of the power spectrum is dependent on galaxy morphology. Early-type galaxies show a higher clustering amplitude than late-type galaxies by a factor of ~ 1.8. There is also tentative evidence for some dependence of the clustering amplitude on galaxy luminosity. The parameter Ω0.6/b is estimated via a comparison with the real-space power spectrum of the two-dimensional APM galaxy survey. For APM clusters the power spectrum is measured to very small wave numbers, with a possible detection of the expected turn-over. The results are inconsistent with the standard cold dark matter model. The shape of P( k) for clusters is approximately the same as that for Stromlo-APM galaxies but amplified by a factor of ~ 3.5. The power spectrum of the QDOT sample depends sensitively on the galaxy weighting scheme, probably due the manner in which the region of the Hercules supercluster is sampled. A best estimate of the power spectrum of IRAS galaxies is computed by combining the IRAS l.2Jy and QDOT samples. The PSCz galaxy power spectrum is also computed. The PSCz galaxies have a clustering amplitude twice that of optical galaxies. A similar result is found from a joint counts in cells analysis. Redshift-space distortions in the PSCz sample are analysed using a spherical harmonic decomposition of the density field. The value of Ω0.6/b = 1 is ruled out by this analysis at the 2σ significance level.

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Mendes, Luís Miguel Vinhas. "Measurements and analysis of spectrum activity". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7725.

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Mestrado em Engenharia Electrónica e Telecomunicações
The dissertation deals with measuring and analyzing spectrum occupancy of a GSM900 band, DCS1800 band and all UMTS bandwidth. A modelization for analog power and binary quantized power is given. In the case of analog power, histograms of the power distribution during one working day are presented. In the case of quantized power the two time statistics, the time period of opportunities distribution and the time between opportunities distribution are presented, described and modeled. The measurement setup is standing in line of sight with the base station. Also, in terms of maximum sensitivity the measurement setup is described and analyzed. Spectrum non occupancy in terms of total time for the GSM900 band and the DCS1800 band is given, for a working day.
Nesta dissertação são feitas medidas e a análise de ocupação de espectro em uma banda de GSM900, uma banda de DCS1800 e toda a largura de banda do UMTS. É apresentada uma modelização para potência analógica e para a potência binária quantizada. No caso da potência analógica são apresentados histogramas da distribuição de potência ao longo de um dia útil. No caso da potência quantizada as duas estatísticas, distribuição do período de tempo de oportunidades e distribuição do tempo entre oportunidades, são apresentadas, descritas e modeladas. O setup de medida encontra-se em linha de vista com a estação base. O setup é descrito e analisado em termos de máxima sensibilidade. A desocupação de espectro em termos de tempo total para a banda de GSM900 e para a banda DCS1800 é fornecida, para um dia de útil.

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Clayton, Michael J. "Analysis of the ultraviolet emissions of nitric oxide from mid-latitude rocket observations". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237340.

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Thesis (M.S. in Physics)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Cleary, David D. "June 1990." Description based on signature page. as viewed on October 19, 2009. DTIC Identifiers: Dayglow, emission spectra, ultraviolet spectra, theses. Author(s) subject terms: Ultraviolet spectra, dayglow, nitric oxide. Includes bibliographical references (p. 57-58). Also available in print.

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Strachan, Clare, e n/a. "Spectroscopic investigation and quantitation of polymorphism and crystallinity of pharmaceutical compounds". University of Otago. School of Pharmacy, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070427.141108.

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Spectroscopy is increasingly used to investigate and monitor the solid state forms of pharmaceutical materials and products. Spectroscopy�s speed, nondestructive sampling, compatibility with fibre optics and safety also make it attractive for in-line monitoring. In this thesis, the spectroscopic techniques Fourier transform Raman spectroscopy, terahertz pulsed spectroscopy and second harmonic generation were used to characterise and quantify polymorphism and crystallinity of pharmaceutical compounds. Where possible, the multivariate analysis technique partial least squares was used for quantitative analysis. Fourier transform Raman spectroscopy detects polarisability changes mainly associated with molecular vibrations. Terahertz pulsed spectroscopy is a new spectroscopic technique that operates between the infrared and microwave regions of the electromagnetic spectrum and detects dipole moment changes mainly associated with crystalline phonon vibrations in the solid state. Second harmonic generation is a nonlinear optical phenomenon that depends on the dipole moment in crystals and crystal symmetry. Several materials capable of existing in different solid state forms were used. FT-Raman spectroscopy was able to differentiate carbamazepine forms I and III, enalapril maleate forms I and II and γ-crystalline and amorphous indomethacin. Combined with partial least squares the technique could quantify binary mixtures of CBZ forms I and III with a limit of detection as low as 1%, and mixtures of enalapril maleate with a limit of detection of as low as 2%. Terahertz pulsed spectroscopy obtained very different spectra for carbamazepine forms I and III, enalapril maleate forms I and II, γ-crystalline and amorphous indomethacin, crystalline and supercooled thermotropic liquid crystalline fenoprofen calcium, three forms of lactose, and five forms of sulphathiazole. At present the modes in the spectra cannot be attributed to specific phonon modes. Quantitation of binary mixtures of different forms of a compound using partial least squares analysis usually resulted in a limit of detection of about 1%. Second harmonic generation was used to quantify binary mixtures of different forms of enalapril maleate and lactose, as well as binary mixtures of enalapril maleate form II and polyvinylpyrrolidone. A quantitative relationship was present for each of the mixtures, however the limits of detection were usually above 10%. The high value is probably due to the machine being a prototype and univariate analysis associated with a single output variable. Future improvements to the apparatus and measurement parameters are likely to reduce the limits of detection. Ranitidine hydrochloride polymorphs could also be differentiated using second harmonic generation, however γ-crystalline and amorphous indomethacin and forms I and III of carbamazepine could not. The methods used in this thesis were successfully used for qualitative and quantitative analysis of polymorphism and crystallinity of pharmaceutical compounds. TPS and SHG are useful additions to the range of experimental techniques that can be used to investigate and monitor properties of pharmaceutical solids.

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Youatt, Andrew Pierce. "Analyzing Edgard Varese's Ionisation Using Digital Spectral Analysis". Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/232473.

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Although Robert Cogan's New Images of Musical Sound won the Society of Music Theory's Outstanding Publication Award in 1987, his musical application of spectral analysis has seen little use over the past 25 years. Spectral images are most effective at illustrating the timbre of sound, and harmony, not timbre, is the key structural component of most Western music. There are, however, some compositions in which timbre plays a critical role. Chief among these is Edgard Varèse's Ionisation, an epic percussion ensemble piece built around 40 instruments and 13 musicians. Previous analyses by Jean-Charles François and Varèse protege Chou Wen-Chung have emphasized the importance of timbre to Ionisation's construction, but are limited in their exploration of timbral qualities. Modern digital spectral analysis allows for a more accurate picture of the individual timbres that make up Ionisation and define the broader textures and structures that give the piece meaning.

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Daigle, J. A. Bernard. "Development of an ion trap mass spectrometer for elemental analysis". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30688.

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Mass spectrometry is a widely used technique for the performance of elemental analysis: not only does it provides excellent limits of detection for a large number of elements, but it is also able to provide information about the isotopic distribution of the analyte. The radio-frequency quadrupole ion trap is a relatively new design of mass spectrometer, which offers the ability to confine charged particles for extended periods of time in a well defined volume by applying a radio-frequency oscillating voltage to an arrangement of three electrodes. A mass analysis of the trapped ions can be obtained by selectively extracting the ions from the cavity of the trap, where they can be detected by an electron multiplier. Despite its unique capabilities, to date the applications of the ion trap mass spectrometer have mostly been restricted to gas chromatography detection. Until recently, there have been very few attempts to use it for any other types of routine analysis. Our interest lies in the development of an instrument capable of performing a complete mass spectrometric elemental analysis of small volume liquid samples (a few (μL) at trace or ultra-trace concentration levels. The ability of the ion trap to accumulate ions in its cavity and to provide an entire mass spectrum of these ions in a single scan of the radio-frequency oscillating voltage applied between the electrodes, makes it a very interesting candidate for the ultra-trace analysis of small size samples. However, to perform an analysis on a sample with the ion trap the sample must first be vaporized; and if an elemental analysis is required, the sample will also have to be atomized. The graphite furnace atomizer used in atomic absorption spectroscopy offers a number of advantages which make it potentially useful for this purpose: it has a high transport efficiency of the analyte from liquid or solid state to the vapour phase, the ionization of the analyte in the furnace is very low (as required by the ion trap) and it handles small volume samples very well. A graphite furnace ion trap mass spectrometer was designed to fulfil the need of having instrumentation capable of multielemental mass spectrometric analysis of small volume samples containing traces of the analytes of interest. This document contains a description of the principles of operation of the ion trap as well as a detailed description of the instrument actually built. Data are presented in order to assess the capabilities of the instrument, as well as some of the problems encountered with it. The results obtained with the graphite furnace ion trap mass spectrometer allow us to conclude that the proposed design is not appropriate for the performance of elemental analysis, but is appropriate for mass spectrometric study of low boiling point compounds which can interfere with atomic absorption analysis: it is calculated that these compounds could be analysed at the ppm level. Promising results obtained with a set up in which the analyte is vaporized directly into the cavity of the ion trap through laser ablation are also presented. These limited results show the potential of this methodology for direct elemental analysis of solid samples.
Science, Faculty of
Chemistry, Department of
Graduate

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Libri sul tema "Spectrum analysis"

1

Hassani, Hossein, e Rahim Mahmoudvand. Singular Spectrum Analysis. London: Palgrave Macmillan UK, 2018. http://dx.doi.org/10.1057/978-1-137-40951-5.

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Fulop, Sean A. Speech Spectrum Analysis. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17478-0.

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Elsner, James B., e Anastasios A. Tsonis. Singular Spectrum Analysis. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4757-2514-8.

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Fulop, Sean A. Speech Spectrum Analysis. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2011.

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5

Rauscher, Christoph. Fundamentals of spectrum analysis. München: Rohde & Schwarz, 2002.

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1942-, Kesler Stanislav B., a cura di. Modern spectrum analysis, II. New York: IEEE Press, 1986.

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Ingle, James D. Spectrochemical analysis. London: Prentice-Hall International, 1988.

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Haris, P. I., e Feride Severcan. Vibrational spectroscopy in diagnosis and screening. Amsterdam: IOS Press, 2012.

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Elsner, James B. Singular spectrum analysis: A new tool in time series analysis. New York: Plenum Press, 1996.

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Golyandina, Nina, Anton Korobeynikov e Anatoly Zhigljavsky. Singular Spectrum Analysis with R. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-57380-8.

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Capitoli di libri sul tema "Spectrum analysis"

1

Miyara, Federico. "Spectrum Analysis". In Modern Acoustics and Signal Processing, 245–95. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55871-4_8.

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2

Cady, Ernest B. "Spectrum Analysis". In Clinical Magnetic Resonance Spectroscopy, 247–68. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-1333-5_6.

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Weik, Martin H. "spectrum analysis". In Computer Science and Communications Dictionary, 1634. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_17898.

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Yosida, Kôsaku. "Resolvent and Spectrum". In Functional Analysis, 209–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-61859-8_9.

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Lang, Serge. "The Spectrum". In Real and Functional Analysis, 400–414. New York, NY: Springer New York, 1993. http://dx.doi.org/10.1007/978-1-4612-0897-6_16.

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Jacobsen, Eric, e Richard Lyons. "Sliding Spectrum Analysis". In Streamlining Digital Signal Processing, 175–88. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118316948.ch18.

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Turner, J. D. "Practical Spectrum Analysis". In Instrumentation for Engineers, 180–202. New York, NY: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-6300-2_8.

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Radojičić, U., K. Nordhausen e S. Taskinen. "Singular Spectrum Analysis". In Encyclopedia of Mathematical Geosciences, 1–5. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-26050-7_294-1.

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Turner, J. D. "Practical Spectrum Analysis". In Instrumentation for Engineers, 180–202. London: Macmillan Education UK, 1988. http://dx.doi.org/10.1007/978-1-349-19508-4_8.

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Radojičić, U., Klaus Nordhausen e Sara Taskinen. "Singular Spectrum Analysis". In Encyclopedia of Mathematical Geosciences, 1328–32. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-030-85040-1_294.

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Atti di convegni sul tema "Spectrum analysis"

1

Azimirad, M., A. R. M. Gharabaghi e M. R. Chenaghlou. "Deterministic-Spectral Fatigue Analysis of a Typical Jacket Platform (SPD1) Using Directional Wave Spectrum". In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29418.

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Fixed offshore platforms or Jacket type platforms are the most common offshore structures used for oil & gas Exploration & Production industry in Persian Gulf, because water depth is such that the shallow water condition is dominant. Sea waves as dominant environmental loading are cyclic and have random nature. The applied cyclic sea wave forces will lead to fatigue damages in jacket’s joints. There are different methods to investigate the fatigue life of jackets such as deterministic method, simplified method, spectral method and transient method. Spectral method is a suitable method, which can consider the random nature of sea waves in fatigue analysis. Deterministic-spectral method developed by Bishop et al. is used to estimate the fatigue life of shallow water jacket platforms. However, in this method the frequency spectrum of waves is used in the analysis, but generally sea waves are propagating in different directions with different frequencies, so directional wave spectrum can consider wave randomness more properly. In this paper, frequency domain spectral method using Deterministic-Spectral approach has been used to estimate the fatigue life of a typical jacket platform (SPD1 at South Pars Field - Persian Gulf). Base wave cases were chosen from joint histogram of height & period that is calculated based on scatter diagrams of South Pars Field. First the jacket was modeled by ANSYS software, then by applying base wave cases to it and analyzing the critical TT joint under internal cyclic forces, hot spot stress transfer functions at 8 nodes around the intersection of joint were obtained. Using JONSWAP standard spectrum and the spreading function proposed by Goda, sea state’s Power Spectral Densities (PSD) and directional spectrums are multiplied to obtain stress spectra. The fatigue damage and fatigue life then are calculated. Results indicate that the fatigue life based on frequency spectrum is less than the fatigue life based on directional spectrum.

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Riza, Nabeel A., e Demetri Psaltis. "Optical disk based acousto-optic spectrum analysis". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.tuk5.

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This paper introduces optical disks in acousto-optic spectrum analyzers. In 2-D time and space integrating acousto-optic folded spectrum analyzers, electronic reference signals are used in the temporal spectral processing. In order to obtain complete folded spectrums, these reference signals have to be of extremely high timebandwidth product, and require extremely fast serial readout rates. It is difficult to generate these signals using electronics, and so far, only incomplete folded spectrums have been obtained. We address the signal generation problem by combining the angular motion, high storage capacity, and parallel access capability of optical disks. The disk is introduced as an optical distributed local oscillator generator and a light sampling 1-D spatial light modulator. The distributed local oscillator architecture forms the basis of a continuous wave 1-D time integrating spectrum analyzer. The reference signals are stored as concentric channels on the disk surface. When the disk spins with a constant angular velocity, each circular channel acts as a modulating light source with a specific on/off frequency. This angular motion creates an array of temporal oscillators along the radial direction of the disk. When the input test signal frequency matches one of the disk channel temporal frequencies, a positive build-up of charge occurs on the time integrating detector, indicating a frequency match. A simple disk system is demonstrated in the laboratory. The disk can also be used in a 2-D time and space integrating architecture, where radial sections of the disk are used for storing the columns of a DFT matrix used for temporal spectrum analysis.

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Skinner, A. D. "Spectrum analysis". In 14th IEE Microwave Measurements Training Course. IEE, 2005. http://dx.doi.org/10.1049/ic:20050156.

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Xu, HongKun, Fang Fang, Shijun Ni, Jianfeng He e Lei You. "Gamma Spectrum Analysis of Chang’E-1 for Lunar Detection". In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29126.

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Gamma-ray spectrum analysis was essential for detecting the elemental abundance and distribution in lunar science. However, for the low-energy region of gamma-ray spectrum, weak peaks were implicated in the fast-decreasing background, and it was difficult to extract characteristic information from original spectra. In order to get a better analytic result, based on wavelet and FFT filtering methods in frequency domain, we had processed the gamma-ray spectrometer (GRS) data of Chang’E-1 (CE-1), and well extracted some useful information of spectral characteristic peaks. Then we preliminarily mapped the distribution of net peak counts for potassium on lunar surface, which indirectly reflected the distribution of elemental abundance. At last, we compared our analytic result with that of Apollo and Lunar Prospector (LP), and found some consistencies and differences.

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Preppernau, B. L., e P. J. Hargis. "Trace Organic Chemical Detection Using an Ultraviolet Excitation Molecular Beam Fluorometer". In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/laca.1994.tub.5.

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Detection of air-borne environmental contaminants, such as organic solvents, requires unambiguous compound identification and sensitivity to concentrations below those permitted by regulating agencies. One promising detection approach uses a pulsed supersonic molecular beam vacuum expansion in combination with fluorescence signal spectral analysis to identify species in a chemical mixture. Expanding a contaminated atmospheric sample through a supersonic molecular beam expansion acts to cool the sample and greatly reduce the spectral density in a fluorescence or photoionization spectrum. Most organic contaminants of interest have electronic transitions in the ultraviolet with near-featureless broad band fluorescence spectra when recorded at atmospheric pressure and room temperature. By using a supersonic vacuum expansion, cooling to within a few degrees of absolute zero can reduce the effective rotational and translational temperatures of the sample molecules and provide a sharply defined spectra which can be used to unambiguously identify specific molecules and their concentrations.

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6

Dai, Bin, Christopher Jones, Jimmy Price, Darren Gascooke e Anthony Van Zuilekom. "COMPRESSIVE SENSING BASED OPTICAL SPECTROMETER FOR DOWNHOLE FLUID ANALYSIS". In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0112.

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Downhole fluid analysis has the potential to resolve ambiguity in very complex reservoirs. Downhole fluid spectra contain a wealth of information to fingerprint a fluid and help to assess continuity. Commonly, a narrowband spectrometer with limited number of channels is used to acquire optical spectra of downhole fluid. The spectral resolution of this type of spectrometer is low due to limited number of narrowband channels. In this paper, we demonstrate a new type, compressive sensing (CS) based broadband spectrometer that provides accurate and high-resolution spectral measurement. Several specially designed broadband filters are used to simplify the mechanical, electrical, optical, and computational construction of a spectrometer, therefore provides measurement of fluid spectrum with high signal-to-noise ratio, robustness, and a broader spectral range. The compressive sensing spectrometer relies on reconstruction technique to compute the optical spectrum. Based on a large spectral database, containing more than 10000 spectra of various fluids at different temperature and pressure conditions, which were collected using conventional high resolution spectrometer in a lab, the basis functions of the optical spectra of three types of fluids (water, oil and gas/condensate) can be extracted. The reconstruction algorithm first classifies the fluid into one of three fluid types based on multichannel CS spectrometer measurements, the optical spectrum is reconstructed by using linear combination of the basis functions of corresponding fluid type, with weighting coefficients determined by minimizing the difference between calculated detector responses and measured detector responses across multiple optical channels. The reconstructed data may then be used for purposes such as contamination measurement, fluid property trends for reservoir continuity assessment, and digital sampling. Digital sampling is the process of extrapolating clean fluid properties from formation fluids not physically sampled. The reconstruction spectrum covers wavelengths from 500 nm to 3300 nm, which is a wider spectral region than has historically been accessible to formation testers. The expanded wavelength range allows access of the mid-infrared spectral region for which synthetic drilling-fluid components typically have higher optical absorbance. This reconstruction spectra may allow contamination to be directly determined. This paper will discuss the CS optical spectrometer design, fluid classification and spectral reconstruction algorithm. In addition, the applicability of the technique to fluid continuity assessment, sample contamination assessment and digital sampling will also be discussed.

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7

Tangyunyong, Paiboon, Edward I. Cole, Guillermo M. Loubriel, Joshua Beutler, Darlene M. Udoni, Biliana S. Paskaleva e Thomas E. Buchheit. "Power Spectrum Analysis". In ISTFA 2017. ASM International, 2017. http://dx.doi.org/10.31399/asm.cp.istfa2017p0073.

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Abstract We present a new, non-destructive electrical technique, Power Spectrum Analysis (PSA). PSA as described here uses off-normal biasing, an unconventional way of powering microelectronics devices. PSA with off-normal biasing can be used to detect subtle differences between microelectronic devices. These differences, in many cases, cannot be detected by conventional electrical testing. In this paper, we highlight PSA applications related to aging and counterfeit detection.

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8

Nguyen, Hung, e Tien Nguyen. "Power Spectral Analysis for Spectrum Packing Efficiency Evaluation". In 21st International Communications Satellite Systems Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.2003-2238.

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9

Colice, Max, Friso Schlottau, Kelvin Wagner, R. Krishna Mohan, William R. Babbitt, Ivan Lorgere e Jean-Louis Le Gouet. "RF spectrum analysis in spectral hole burning media". In Optical Science and Technology, the SPIE 49th Annual Meeting, a cura di Bahram Javidi e Demetri Psaltis. SPIE, 2004. http://dx.doi.org/10.1117/12.560074.

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10

Gao, Xiang, Xiaozhou Ma, Yuxiang Ma, Guohai Dong e Junliang Gao. "Characteristic Analysis for Spectrum of Swell Dominated Seas With In-Situ Measurements". In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18522.

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Abstract The characteristics of wave spectrum in the swell dominated seas (i.e., the Chancay Bay on the western coast of Peru) are studied based on directional wave spectra measured using the technique of acoustic Doppler current profiler (ADCP). According to the wave rose diagram and the measured wave spectra, this sea area is mainly affected by the swell of the southwest direction and the significant wave height is between 0.7m-2.6m. Moreover, the wave spectra feature the single-peaked spectra and the double-peaked spectra. The JONSWAP spectrum model is adopted to fit single-peaked swell spectra. A close agreement could be found between the observed and fitted spectrum parameters. Hence, the JONSWAP model can be used to describe the single-peaked swell spectra in the sea area studied in this work. As for the double-peaked spectrum, Ochi-Hubble double peak spectrum model and simplified Torsethaugen double peak spectrum model are adopted to fit the wave spectra, respectively. Comparing the fitting results of two double-peaked spectrum modal, it’s possible to conclude that the measured double-peaked spectra can be well represented by the Ochi-Hubble double peak spectrum model.

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Rapporti di organizzazioni sul tema "Spectrum analysis"

1

Zhang, S. Y., e W. T. Weng. Spectrum analysis in beam diagnostics. Office of Scientific and Technical Information (OSTI), aprile 1993. http://dx.doi.org/10.2172/10156565.

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2

Stinnett, Jacob. Notre Dame Plutonium Spectrum Analysis. Office of Scientific and Technical Information (OSTI), settembre 2019. http://dx.doi.org/10.2172/1565811.

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3

Zhang S. Y. e W. Weng. SPECTRUM ANALYSIS IN BEAM DIAGNOSTICS. Office of Scientific and Technical Information (OSTI), aprile 1993. http://dx.doi.org/10.2172/1151279.

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4

Zhang, S. Y., e W. T. Weng. Spectrum analysis in beam diagnostics. Office of Scientific and Technical Information (OSTI), aprile 1993. http://dx.doi.org/10.2172/6536419.

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5

Morgan, William J. DoD Spectrum Management: A Critical Analysis. Fort Belvoir, VA: Defense Technical Information Center, giugno 2008. http://dx.doi.org/10.21236/ada525857.

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6

Wilson, R. D. Spectrum shape-analysis techniques applied to the Hanford Tank Farms spectral gamma logs. Office of Scientific and Technical Information (OSTI), maggio 1997. http://dx.doi.org/10.2172/501524.

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7

Anderson, I. M., e J. Bentley. Multivariate statistical analysis of spectrum lines and images. Office of Scientific and Technical Information (OSTI), aprile 1997. http://dx.doi.org/10.2172/505348.

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8

Bezler, P., J. R. Curreri, Y. K. Wang e A. K. Gupta. Alternate modal combination methods in response spectrum analysis. Office of Scientific and Technical Information (OSTI), ottobre 1990. http://dx.doi.org/10.2172/6433723.

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9

Anderson, I. M. Statistical analysis of low-voltage EDS spectrum images. Office of Scientific and Technical Information (OSTI), marzo 1998. http://dx.doi.org/10.2172/658437.

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10

DeJong, Stephanie, Rosalie Multari, Kelsey Wilson e Paiboon Tangyunyong. Evaluation of COTS Electronics by Power Spectrum Analysis and Multivariate Data Analysis. Office of Scientific and Technical Information (OSTI), settembre 2022. http://dx.doi.org/10.2172/1890397.

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