Статті в журналах: "High Spectral Resolution"

1

Meek, R. A., and A. A. Vassiliou. "Characterizing three‐dimensional wavefields with high‐resolution spectra." GEOPHYSICS 57, no. 4 (April 1992): 522–31. http://dx.doi.org/10.1190/1.1443266.

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Three‐dimensional spectra (frequency‐x‐wavenumber‐y‐wavenumber or [Formula: see text] spectra) can be used to determine the frequency content, velocity, and direction of waves entering an array of receivers. This information is important in detecting aliasing problems, understanding coherent noise, designing arrays, and determining parameters for coherent noise filters. Because of the limited spatial dimensions of most arrays the discrete Fourier transform produces an estimate of the three‐dimensional (3-D) spectrum with severe wavenumber distortion. We extend a 2-D hybrid spectral estimation method to three dimensions by combining a temporal Fourier transform with a spatial 2-D maximum entropy spectral estimation technique. The method produces [Formula: see text] spectra with higher wavenumber resolution and less spectral distortion than corresponding 3-D Fourier spectra. The 2-D maximum entropy spectral estimation algorithm uses a sequence of Fourier transforms to extrapolate the estimated autocorrelation function of the data. We assume the wavenumber spectrum of the data comprises a sum of a few poles. Field and synthetic data are used to demonstrate how 3-D wavefields can be characterized with this method of spectral analysis. From these results we conclude that the method gives excellent wavenumber resolution but performs poorly in detecting small signals in the presence of high amplitude signals. We feel this limitation is not serious for characterizing strong amplitude coherent energy recorded by an array of receivers.

2

Chen, Lin-sen, Tao Yue, Xun Cao, Zhan Ma, and David J. Brady. "High-resolution spectral video acquisition." Frontiers of Information Technology & Electronic Engineering 18, no. 9 (September 2017): 1250–60. http://dx.doi.org/10.1631/fitee.1700098.

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3

Chouza, Fernando, Benjamin Witschas, and Oliver Reitebuch. "Heterodyne high-spectral-resolution lidar." Applied Optics 56, no. 29 (October 4, 2017): 8121. http://dx.doi.org/10.1364/ao.56.008121.

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4

Dahlhaus, R. "Nonparametric high resolution spectral estimation." Probability Theory and Related Fields 85, no. 2 (June 1990): 147–80. http://dx.doi.org/10.1007/bf01277980.

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5

Allen, G., J. J. Remedios, D. A. Newnham, K. M. Smith, and P. S. Monks. "High resolution mid-infrared cross-sections for peroxyacetyl nitrate (PAN) vapour." Atmospheric Chemistry and Physics Discussions 4, no. 5 (September 22, 2004): 5655–81. http://dx.doi.org/10.5194/acpd-4-5655-2004.

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Abstract. Absorption spectra of peroxyacetyl nitrate (PAN, CH3C(O)OONO2) vapour at room temperature (295 K) have been measured in the mid-infrared range, 550–2200 cm−1 (18.2–3.33 µm), using a Fourier transform infrared spectrometer at instrument resolutions of 0.25 and 0.03 cm−1 (unapodised). Both cross-section data and integrated absorption intensities for the five principal bands in the PAN spectra in this spectral range have been derived from fourteen separate PAN transmission spectra measurements. Band intensities and band centre absorptivities are also reported for four weaker PAN absorption bands in the mid infrared for the first time. These observations are the highest spectral resolution measurements of PAN bands recorded in the infrared to date. For three of the five strongest bands, the absolute integrated absorption intensities are in excellent agreement with previous studies. A 4.8% lower integrated intensity was found for the 1741 cm−1 νas (NO2) PAN absorption band, possibly as a result of the removal in this work of spectra affected by subtle acetone contamination, while a 10.6% higher intensity was determined for the 1163 cm−1 ν (C-O) absorption band. No direct effects of spectral resolution were observed. The improved accuracy of these absorption cross-sections will allow more accurate investigations of PAN using infrared spectroscopy, particularly for remote sensing of PAN in the atmosphere.

6

Conrads, T. P., V. A. Fusaro, S. Ross, D. Johann, V. Rajapakse, B. A. Hitt, S. M. Steinberg, et al. "High-resolution serum proteomic features for ovarian cancer detection." Endocrine-related cancer 11, no. 2 (June 2004): 163–78. http://dx.doi.org/10.1677/erc.0.0110163.

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Serum proteomic pattern diagnostics is an emerging paradigm employing low-resolution mass spectrometry (MS) to generate a set of biomarker classifiers. In the present study, we utilized a well-controlled ovarian cancer serum study set to compare the sensitivity and specificity of serum proteomic diagnostic patterns acquired using a high-resolution versus a low-resolution MS platform. In blinded testing sets, the high-resolution mass spectral data contained multiple diagnostic signatures that were superior to the low-resolution spectra in terms of sensitivity and specificity (P<0.00001) throughout the range of modeling conditions. Four mass spectral feature set patterns acquired from data obtained exclusively with the high-resolution mass spectrometer were 100% specific and sensitive in their diagnosis of serum samples as being acquired from either unaffected patients or those suffering from ovarian cancer. Important to the future of proteomic pattern diagnostics is the ability to recognize inferior spectra statistically, so that those resulting from a specific process error are recognized prior to their potentially incorrect (and damaging) diagnosis. To meet this need, we have developed a series of quality-assurance and in-process control procedures to (a) globally evaluate sources of sample variability, (b) identify outlying mass spectra, and (c) develop quality-control release specifications. From these quality-assurance and control (QA/QC) specifications, we identified 32 mass spectra out of the total 248 that showed statistically significant differences from the norm. Hence, 216 of the initial 248 high-resolution mass spectra were determined to be of high quality and were remodeled by pattern-recognition analysis. Again, we obtained four mass spectral feature set patterns that also exhibited 100% sensitivity and specificity in blinded validation tests (68/68 cancer: including 18/18 stage I, and 43/43 healthy). We conclude that (a) the use of high-resolution MS yields superior classification patterns as compared with those obtained with lower resolution instrumentation; (b) although the process error that we discovered did not have a deleterious impact on the present results obtained from proteomic pattern analysis, the major source of spectral variability emanated from mass spectral acquisition, and not bias at the clinical collection site; (c) this variability can be reduced and monitored through the use of QA/QC statistical procedures; (d) multiple and distinct proteomic patterns, comprising low molecular weight biomarkers, detected by high-resolution MS achieve accuracies surpassing individual biomarkers, warranting validation in a large clinical study.

7

Sato, Harumi, Masahiko Shimoyama, Taeko Kamiya, Toru Amari, Slobodan Šašiç, Toshio Ninomiya, Heinz W. Siesler, and Yukihiro Ozaki. "Near Infrared Spectra of Pellets and Thin Films of High-Density, Low-Density and Linear Low-Density Polyethylenes and Prediction of Their Physical Properties by Multivariate Data Analysis." Journal of Near Infrared Spectroscopy 11, no. 4 (August 2003): 309–21. http://dx.doi.org/10.1255/jnirs.376.

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The aim of the present study is to investigate in detail the near infrared (NIR) spectra of the three types of polyethylene, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and to develop calibration models that predict their physical properties such as density, crystallinity and melting point. The effects of spectral resolution on the classification and the prediction of density for the three types of PE have been investigated. Furthermore, the NIR spectral differences among LLDPE, LDPE and HDPE have been explored in more detail using 2 cm−1 resolution. Principal component analysis (PCA) has been performed to differentiate the 18 samples of PE. They are classified into three groups, LLDPE, LDPE and HDPE, by a score plot of the PCA Factor 1 versus 3 based on the NIR spectra pretreated by multiplicative scatter correction (MSC). The 2 cm−1 spectral resolution yields a slightly better result for the classification. Partial least squares (PLS) regression has been applied to the NIR spectra after MSC to propose calibration models that predict the density, crystallinity and melting point of HDPE, LDPE and LLDPE. The correlation coefficient for the density was calculated to be 0.9898, 0.9928, 0.9925 and 0.9872 for the spectra obtained at 2, 4, 8 and 16 cm−1 resolutions, respectively, and the root mean square error of cross validation ( RMSECV) was found to be 0.0021, 0.0018, 0.0018 and 0.0023 g cm−3, respectively. It has been found that the correlation coefficient and RMSECV for the prediction of the density and crystallinity change little with the spectral resolution. However, for the prediction of melting point, the higher resolutions (2 and 4 cm−1 resolution) provide slightly better results than the lower resolutions. NIR transmission spectra of thin films of LLDPE, LDPE and HDPE have also been investigated, and calibration models for predicting their density have been developed for the film spectra.

8

Martinez, Zorayda, Simon Gazagnes та Danielle A. Berg. "Instrumental Effects of Lyα Properties in CLASSY and Implication for HETDEX and JWST". Research Notes of the AAS 7, № 10 (3 жовтня 2023): 205. http://dx.doi.org/10.3847/2515-5172/acfe7f.

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Abstract In this work, we quantify the effects of spectral resolution (R) on the measured Lyα properties and determine the robustness of Lyα trends measured with different spectrographs. We select 9 galaxies with diverse Lyα properties from the COS Legacy Archive Spectroscopic SurveY and measure the equivalent width and peak velocities of their Lyα profiles from their high-resolution spectra (R ∼ 4225–15000). We downgrade these spectra to several lower resolutions (R ∼ 800–3500) and re-measure the Lyα properties. Using these values, we derive the systematic errors and investigate the robustness of Lyα properties as a function of spectral resolution. We find that equivalent width can be robustly measured at low R. However, the minimal spectral resolution required to obtain robust measurements of the Lyα peak velocities is R ≳ 2600 (Δv = 115 km s−1).

9

Qajar, Ch O., S. B. Kazymova, M. R. Menzeleyev, and A. S. Gasanova. "Low Resolution Rotational Spectra of Phenol." Applied Physics Research 10, no. 6 (November 30, 2018): 77. http://dx.doi.org/10.5539/apr.v10n6p77.

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The modeling of low-resolution (LR) microwave spectra of phenol C6H5OH molecule has been provided in the frequency regions of 0-700 GHz basing on high-resolution (HR) microwave spectral data. The frequency ranges of most intensive absorption level of low-resolution microwave spectra determined. The most intensive spectral lines forming spectra extremums are developed. The recommendations related to perspectives of practical use of achieved results are given.

10

Sadygov, Rovshan G. "High-Resolution Mass Spectrometry for In Vivo Proteome Dynamics using Heavy Water Metabolic Labeling." International Journal of Molecular Sciences 21, no. 21 (October 22, 2020): 7821. http://dx.doi.org/10.3390/ijms21217821.

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Cellular proteins are continuously degraded and synthesized. The turnover of proteins is essential to many cellular functions. Combined with metabolic labeling using stable isotopes, LC–MS estimates proteome dynamics in high-throughput and on a large scale. Modern mass spectrometers allow a range of instrumental settings to optimize experimental output for specific research goals. One such setting which affects the results for dynamic proteome studies is the mass resolution. The resolution is vital for distinguishing target species from co-eluting contaminants with close mass-to-charge ratios. However, for estimations of proteome dynamics from metabolic labeling with stable isotopes, the spectral accuracy is highly important. Studies examining the effects of increased mass resolutions (in modern mass spectrometers) on the proteome turnover output and accuracy have been lacking. Here, we use a publicly available heavy water labeling and mass spectral data sets of murine serum proteome (acquired on Orbitrap Fusion and Agilent 6530 QToF) to analyze the effect of mass resolution of the Orbitrap mass analyzer on the proteome dynamics estimation. Increased mass resolution affected the spectral accuracy and the number acquired tandem mass spectra.

11

Meftah, Mustapha, Alain Sarkissian, Philippe Keckhut, and Alain Hauchecorne. "The SOLAR-HRS New High-Resolution Solar Spectra for Disk-Integrated, Disk-Center, and Intermediate Cases." Remote Sensing 15, no. 14 (July 15, 2023): 3560. http://dx.doi.org/10.3390/rs15143560.

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The solar spectrum at the top of the atmosphere contains crucial data for solar physics, astronomy, and geophysics. Accurately determining high-resolution solar reference spectra, whether they are disk-integrated, disk-center, or intermediate cases, represents a new challenge and is of primary importance for all applications where spectral solar radiation needs to be evaluated. These spectra are also essential for interpreting remote sensing measurements that rely on sunlight, such as those obtained by Earth observation satellites or spacecraft exploring other planets. This paper lays a foundation for the implementation of multiple new solar irradiance reference spectra that have high resolution and are representative of solar minimum conditions. We developed the SOLAR high-resolution extraterrestrial reference spectra (SOLAR-HRS disk-integrated spectra) by normalizing high-spectral-resolution solar line data to the absolute irradiance scale of the SOLAR-ISS reference spectrum. The resulting one-of-a-kind SOLAR-HRS disk-integrated spectrum has a spectral resolution varying between 0.001 and 1 nm in the 0.5–4400 nm wavelength range. We also implemented a new high-resolution solar spectrum at the disk-center, covering a range of 650–4400 nm with a spectral resolution of 0.001 to 0.02 nm. We further expanded our analysis by producing several solar spectra for ten different solar view angles ranging from μ = 0.9 to μ = 0.05 (SOLAR-HRS intermediate cases). Finally, we developed new Merged Parallelised Simplified ATLAS spectra (MPS-ATLAS) based on solar modeling with Kurucz and Vald3 solar linelists for both the disk-integrated and disk-center spectra. One of the objectives of implementing all these new solar spectra is to fulfill the requirements of the MicroCarb space mission, which focuses on measuring greenhouse gas emissions. The solar data of this study are openly available.

12

Qin, Yusheng, Jingjing Tong, Xiangxian Li, Xin Han, and Minguang Gao. "The Effect of Spectral Resolution on the Quantification of OP-FTIR Spectroscopy." Photonics 10, no. 4 (April 21, 2023): 475. http://dx.doi.org/10.3390/photonics10040475.

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Open-path Fourier Transform infrared spectroscopy (OP-FTIR) is widely used in polluted gas monitoring. The spectral resolution, as a key parameter of FTIR detection technology, affects the quantitative analysis of gas concentration. In OP-FTIR, the nonlinear least square (NLLS) method based on a synthetic background spectrum is used to quantitatively analyze the gas concentration, and the influence of the spectral resolution is studied. It is found that the influence of the spectral resolution on quantitative gas analysis is related to the full width at half maximum (FWHM) of the gas spectrum. The concentration of gases with different spectral FWHMs were quantitatively analyzed using infrared spectra with different resolutions (1, 2, 4, 8, 16 cm−1). The experimental results show that the relatively optimal spectral resolution for propane (C3H8) with a broad FWHM is 16 cm−1, where the standard deviation is 0.661 and the Allan deviation is only 0.015; the relatively optimal spectral resolution for ethylene (C2H4) with a narrow FWHM is 1 cm−1, where the standard deviation is 0.492 and the Allan deviation is only 0.256. Therefore, for the NLLS quantitative analysis method based on the synthetic background spectrum, which is used in OP-FTIR, gas with a narrow FWHM at high resolutions or gas with a broad FWHM at low resolutions is most effective for performing quantitative analyses.

13

Ferus, M., P. Kubelík, L. Petera, L. Lenža, J. Koukal, A. Křivková, V. Laitl, et al. "Main spectral features of meteors studied using a terawatt-class high-power laser." Astronomy & Astrophysics 630 (October 2019): A127. http://dx.doi.org/10.1051/0004-6361/201935816.

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Context. Meteor spectra are commonly interpreted using data from databases and tables. Several studies have demonstrated very sophisticated calculations of elemental compositions of meteoroid bodies based on the computation of synthetic meteor spectra or on the spectral analysis of airglow plasma containing evaporated, atomized, and ionized meteoroid matter. However, considering accuracy, reliability of computations, lack of laboratory experimental data in this field, as well as the complicated physical structure of meteor plasma, such qualitative assignment or quantitative calculations are still extensively discussed in the scientific community. Even on the laboratory level, many studies have shown the high complexity of the acquisition and interpretation of the data that are recorded with techniques of emission spectroscopy that are in fashion and philosophy similar to the spectral analysis of meteor plasma, that is, detection and quantification of the elements that are ablated from complicated multicomponent matrices. Aims. The current study is focused on the application of terawatt-class laser-induced breakdown spectroscopy (TC-LIBS) of real samples of chondritic meteorites. We recorded emission spectra with high resolution and high precision that contain spectral lines that are typical for real meteoric spectra. Experimental data were compiled in a form that is convenient for the meteoric spectra interpretation and calibration. Methods. TC-LIBS was carried out by a high-power terawatt-class laser facility, the Prague Asterix Laser System (PALS). The spectra were simultaneously recorded by an echelle high-resolution spectrograph in the UV/VIS spectral ranges and by a low-resolution spectrograph that was used for real observation of meteor spectra. We also present calculated synthetic spectra based on data from the NIST atomic spectra database. Results. We assembled etalon qualitative tables of major meteoric spectral features that can be used both for the spectral wavelength calibration of low-resolution observational instruments and for the exact interpretation of meteor spectra. The data are compared with real meteor spectra.

14

Kolosov, N. A., S. S. Boldova, and V. A. Labusov. "Investigation of atomic vapor absorption spectra on the high-resolution spectrometer "Grand-2000"." Interexpo GEO-Siberia 8, no. 1 (May 18, 2022): 112–16. http://dx.doi.org/10.33764/2618-981x-2022-8-1-112-116.

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The work is devoted to the study of atomic vapor absorption spectra obtained in the electrothermal atomizer (graphite furnace) and registered by the high-resolution spectrometer "Grand-2000" (spectral resolution 4 pm). Comparison of the obtained spectra with the spectra recorded by the "Grand-2" spectrometer, which is a part of the "Grand-AAS" atomic absorption spectrometer, indicated the presence of unresolved spectral interferences in the latter, as well as a number of unresolved doublets of analytical lines, both already presented in the database of spectral absorption lines of chemical elements, and missing in it. Based on the results of the work, we can talk about the suitability of the "Grand-2000" spectrometer for adjusting this database.

15

Allende Prieto, Carlos. "The GTC gains high spectral resolution." Nature Astronomy 5, no. 1 (January 2021): 105. http://dx.doi.org/10.1038/s41550-020-01280-1.

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16

Postma, S., P. van der Walle, H. L. Offerhaus, and N. F. van Hulst. "Compact high-resolution spectral phase shaper." Review of Scientific Instruments 76, no. 12 (December 2005): 123105. http://dx.doi.org/10.1063/1.2140465.

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17

D. Küntz, K., D. Koutroumpa, W. R. Dunn, A. Foster, F. S. Porter, D. G. Sibeck, and B. Walsh. "The magnetosheath at high spectral resolution." Earth and Planetary Physics 8, no. 1 (2024): 1–13. http://dx.doi.org/10.26464/epp2023060.

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18

Linsky, Jeffrey L. "Goals for the Application of High-Resolution X-ray Spectroscopy to the Diagnosis of Stellar Coronal Plasmas." International Astronomical Union Colloquium 115 (1990): 94–109. http://dx.doi.org/10.1017/s0252921100012197.

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AbstractI provide examples of how high-resolution x-ray spectra may be used to determine the temperature and emission measure distributions, electron densities, steady and transient flow velocities, and location of active regions in stellar coronae. For each type of measurement I estimate the minimum spectral resolution required to resolve the most useful spectral features. In general, high sensitivity is required to obtain sufficient signal-to-noise to exploit the high spectral resolution. Although difficult, each measurement should be achievable with the instrumentation proposed for AXAF.

19

Dzyuba, A. A., S. V. Dodonov, and V. A. Labusov. "Analytical capabilities of the Grand-2000 high-resolution spectrometer." Аналитика и контроль 25, no. 4 (2021): 331–39. http://dx.doi.org/10.15826/analitika.2021.25.4.009.

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The analytical characteristics of the new Grand-2000 high-resolution spectrometer with BLPP-4000 photodetectors were evaluated. The device was tested as part of the Grand-Potok complex, which consists of a spectrometer and an electric arc facility and is designed to analyze powder samples continuously brought into the plasma atomizer (free-burning arc in air). The characteristics of the new spectrometer were compared with those of the Grand spectrometer, which is widely employed in analytical laboratories. It is shown that the use of the Grand-2000 spectrometer to determine the concentration of elements in geological and industrial powder samples does not lead to an obvious improvement in the results. The threefold increase in the spectral resolution of the new spectrometer reduces spectral influences from interfering elements, but the relative systematic error both decreases and increases for different samples. This may indicate the influence of unaccounted-for factors, for example, non-optimal spectra processing algorithms for this device. The results obtained suggest good prospects for the use of the Grand-2000 spectrometer to determine the concentration of elements in samples with a complex spectrum, but they also indicate the need for further studies to determine the optimal parameters for processing spectra. In addition, the Grand-2000 spectrometer can be used to supplement and refine the existing database of the wavelengths of spectral lines.

20

Lewis, M. "Discrimination of arid vegetation composition with high resolution CASI imagery." Rangeland Journal 22, no. 1 (2000): 141. http://dx.doi.org/10.1071/rj0000141.

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CASI (Compact Airborne Spectrographic Imager) airborne imagery, with high spectral and spatial resolution, was evaluated for the discrimination of composition and variation in arid vegetation at Fowlers Gap Arid Zone Research Station in western New South Wales. The imagery was calibrated to surface reflectance using field reference spectra collected near the time of the overflight, and analysed in relation to reflectance spectra of plants at Fowlers Gap. Maps showing abundance of total perennial vegetation, chenopod shrubs and trees, were produced using methods that separated the vegetation contribution from mixed-pixel responses. Results of these analyses were compared with field data on percentage ground cover for 85 one hectare sample plots, collected within four weeks of the overflight. In all cases, the cover of vegetation that was discriminated and mapped was less than 25%. The study demonstrates that high-spectral resolution imagery, combined with new approaches to image analysis, offers considerable scope for discrimination of vegetation variation in arid landscapes. It is possible to spectrally discriminate and map the abundance of several functional vegetation components, even in sparse vegetation, and this information is particularly relevant for management applications. As imagery from high-spectral resolution sensors, both air- and satellite-borne, becomes more readily available in Australia, the benefits to be derived from these data will be more widely applied. Key words: arid vegetation, species composition, hyperspectral imagery, remote sensing, vegetation spectra

21

Yoon, Hoon Hahn, Henry A. Fernandez, Fedor Nigmatulin, Weiwei Cai, Zongyin Yang, Hanxiao Cui, Faisal Ahmed, et al. "Miniaturized spectrometers with a tunable van der Waals junction." Science 378, no. 6617 (October 21, 2022): 296–99. http://dx.doi.org/10.1126/science.add8544.

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Miniaturized computational spectrometers, which can obtain incident spectra using a combination of device spectral responses and reconstruction algorithms, are essential for on-chip and implantable applications. Highly sensitive spectral measurement using a single detector allows the footprints of such spectrometers to be scaled down while achieving spectral resolution approaching that of benchtop systems. We report a high-performance computational spectrometer based on a single van der Waals junction with an electrically tunable transport-mediated spectral response. We achieve high peak wavelength accuracy (∼0.36 nanometers), high spectral resolution (∼3 nanometers), broad operation bandwidth (from ∼405 to 845 nanometers), and proof-of-concept spectral imaging. Our approach provides a route toward ultraminiaturization and offers unprecedented performance in accuracy, resolution, and operation bandwidth for single-detector computational spectrometers.

22

Zhao, Sha, Yufei Yang, Yujie Zhao, Xinming Li, Yi Xue, and Shenlin Wang. "High-resolution solid-state NMR spectroscopy of hydrated non-crystallized RNA." Chemical Communications 55, no. 93 (2019): 13991–94. http://dx.doi.org/10.1039/c9cc06552k.

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23

Millán-Irigoyen, I., M. Mollá, M. Cerviño, Y. Ascasibar, M. L. García-Vargas, and P. R. T. Coelho. "HR-pypopstar: high-wavelength-resolution stellar populations evolutionary synthesis model." Monthly Notices of the Royal Astronomical Society 506, no. 4 (July 12, 2021): 4781–99. http://dx.doi.org/10.1093/mnras/stab1969.

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ABSTRACT We present the HR-pyPopStar model, which provides a complete set (in ages) of high-resolution (HR) spectral energy distributions of Single Stellar Populations. The model uses the most recent high-wavelength-resolution theoretical atmosphere libraries for main-sequence, post-AGB/planetary nebulae and Wolf–Rayet stars. The spectral energy distributions are given for more than a hundred ages ranging from 0.1 Myr to 13.8 Gyr, at four different values of the metallicity (Z = 0.004, 0.008, 0.019, and 0.05), considering four different IMFs. The wavelength range goes from 91 to $24\, 000$ Å in linear steps δλ = 0.1 Å, giving a theoretical resolving power $R_{{\rm th},5000} \sim 50\, 000$ at 5000 Å. This is the main novelty of these spectra, unique for their age and wavelength ranges. The models include the ionizing stellar populations that are relevant at both young (massive hot stars) and old (planetary nebulae) ages. We have tested the results with some examples of HR spectra recently observed with MEGARA at GTC. We highlight the importance of wavelength resolution in reproducing and interpreting the observational data from the last and forthcoming generations of astronomical instruments operating at 8–10 m class telescopes, with higher spectral resolution than their predecessors.

24

Yang, Qinghua. "Broadband high-spatial-resolution high-spectral-resolution flexible imaging spectrometer design study." Applied Optics 60, no. 34 (November 22, 2021): 10490. http://dx.doi.org/10.1364/ao.431247.

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25

Dravins, Dainis, Hans-Günter Ludwig, and Bernd Freytag. "Spatially resolved spectroscopy across stellar surfaces." Astronomy & Astrophysics 649 (April 28, 2021): A16. http://dx.doi.org/10.1051/0004-6361/202039995.

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Context. High-precision stellar analyses require hydrodynamic 3D modeling. Such models predict changes across stellar disks of spectral line shapes, asymmetries, and wavelength shifts. For testing models in stars other than the Sun, spatially resolved observations are feasible from differential spectroscopy during exoplanet transits, retrieving spectra of those stellar surface segments that successively become hidden behind the transiting planet, as demonstrated in Papers I, II, and III. Aims. Synthetic high-resolution spectra over extended spectral regions are now available from 3D models. Similar to other ab initio simulations in astrophysics, these data contain patterns that have not been specifically modeled but may be revealed after analyses to be analogous to those of a large volume of observations. Methods. From five 3D models spanning Teff = 3964–6726 K (spectral types ~K8 V–F3 V), synthetic spectra at hyper-high resolution (λ/Δλ >1 000 000) were analyzed. Selected Fe I and Fe II lines at various positions across stellar disks were searched for characteristic patterns between different types of lines in the same star and for similar lines between different stars. Results. Spectral-line patterns are identified for representative photospheric lines of different strengths, excitation potentials, and ionization levels, thereby encoding the hydrodynamic 3D structure. Line profiles and bisectors are shown for various stars at different positions across stellar disks. Absolute convective wavelength shifts are obtained as differences to 1D models, where such shifts do not occur. Conclusions. Observable relationships for line properties are retrieved from realistically complex synthetic spectra. Such patterns may also test very detailed 3D modeling, including non-LTE effects. While present results are obtained at hyper-high spectral resolution, the subsequent Paper V examines their practical observability at realistically lower resolutions, and in the presence of noise.

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Kochukhov, O., and T. Ryabchikova. "Time-Resolved High-Resolution Spectroscopy of roAp Stars." International Astronomical Union Colloquium 185 (2002): 284–87. http://dx.doi.org/10.1017/s0252921100016250.

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AbstractWe report results of Spectroscopic monitoring of the roAp stars γ Equ, α Cir and HR 3831 with the ESO 3.6-meter telescope. Series of very high-resolution and high S/N spectra allowed to resolve changes of line profiles due to the pulsations. We found that pulsational behaviour of all three roAp stars is dominated by the variations of the doubly ionized rare-earth lines. Detailed analysis of the pulsational changes of Nd III and Pr III spectral features allowed us to identify the pulsational mode of γ Equ and to study rotational modulation of the pulsational pattern in the spectra of α Cir and HR 3831.

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Im, Kang-Bin, Moon-Sik Kang, Jiho Kim, Felix Bestvater, Zahir Seghiri, Malte Wachsmuth, and Regis Grailhe. "Two-photon spectral imaging with high temporal and spectral resolution." Optics Express 18, no. 26 (December 7, 2010): 26905. http://dx.doi.org/10.1364/oe.18.026905.

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28

Elaraby, Samar, Sherif M. Abuelenin, Adel Moussa, and Yasser M. Sabry. "Deep Learning on Synthesized Sensor Characteristics and Transmission Spectra Enabling MEMS-Based Spectroscopic Gas Analysis beyond the Fourier Transform Limit." Foundations 1, no. 2 (December 15, 2021): 304–17. http://dx.doi.org/10.3390/foundations1020022.

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Miniaturized Fourier transform infrared spectrometers serve emerging market needs in many applications such as gas analysis. The miniaturization comes at the cost of lower performance than bench-top instrumentation, especially for the spectral resolution. However, higher spectral resolution is needed for better identification of the composition of materials. This article presents a convolutional neural network (CNN) for 3X resolution enhancement of the measured infrared gas spectra using a Fourier transform infrared (FTIR) spectrometer beyond the transform limit. The proposed network extracts a set of high-dimensional features from the input spectra and constructs high-resolution outputs by nonlinear mapping. The network is trained using synthetic transmission spectra of complex gas mixtures and simulated sensor non-idealities such as baseline drifts and non-uniform signal-to-noise ratio. Ten gases that are relevant to the natural and bio gas industry are considered whose mixtures suffer from overlapped features in the mid-infrared spectral range of 2000–4000 cm−1. The network results are presented for both synthetic and experimentally measured spectra using both bench-top and miniaturized MEMS spectrometers, improving the resolution from 60 cm−1 to 20 cm−1 with a mean square error down to 2.4×10−3 in the transmission spectra. The technique supports selective spectral analysis based on miniaturized MEMS spectrometers.

29

Huang, Feng, Peng Lin, Rongjin Cao, Bin Zhou, and Xianyu Wu. "Dictionary Learning- and Total Variation-Based High-Light-Efficiency Snapshot Multi-Aperture Spectral Imaging." Remote Sensing 14, no. 16 (August 22, 2022): 4115. http://dx.doi.org/10.3390/rs14164115.

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Conventional multispectral imaging systems based on bandpass filters struggle to record multispectral videos with high spatial resolutions because of their limited light efficiencies. This paper proposes a multi-aperture multispectral imaging system based on notch filters that overcomes this limitation by allowing light from most of the spectrum to pass through. Based on this imaging principle, a prototype multi-aperture multispectral imaging system comprising notch filters was built and demonstrated. Further, a dictionary learning- and total variation-based spectral super-resolution algorithm was developed to reconstruct spectral images. The simulation results obtained using public multispectral datasets showed that, compared to the dictionary learning-based spectral super-resolution algorithm, the proposed algorithm reconstructed the spectral information with a higher accuracy and removed noise, and the verification experiments confirmed the performance efficiency of the prototype system. The experimental results showed that the proposed imaging system can capture images with high spatial and spectral resolutions under low illumination conditions. The proposed algorithm improved the spectral resolution of the acquired data from 9 to 31 bands, and the average peak signal-to-noise ratio remained above 43 dB, which is 13 dB higher than those of the state-of-the-art coded aperture snapshot spectral imaging methods. Simultaneously, the frame rate of the imaging system was up to 5000 frames/s under natural daylight.

30

Chen, Chaoliang, Yurui Pu, and Weisong Shi. "Low-cost spectrometer design for ultra-high resolution spectral domain optical coherence tomography." Chinese Optics Letters 21, no. 10 (2023): 101101. http://dx.doi.org/10.3788/col202321.101101.

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31

Gewali, Utsav B., Sildomar T. Monteiro, and Eli Saber. "Spectral Super-Resolution with Optimized Bands." Remote Sensing 11, no. 14 (July 11, 2019): 1648. http://dx.doi.org/10.3390/rs11141648.

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Hyperspectral (HS) sensors sample reflectance spectrum in very high resolution, which allows us to examine material properties in very fine details. However, their widespread adoption has been hindered because they are very expensive. Reflectance spectra of real materials are high dimensional but sparse signals. By utilizing prior information about the statistics of real HS spectra, many previous studies have reconstructed HS spectra from multispectral (MS) signals (which can be obtained from cheaper, lower spectral resolution sensors). However, most of these techniques assume that the MS bands are known apriori and do not optimize the MS bands to produce more accurate reconstructions. In this paper, we propose a new end-to-end fully convolutional residual neural network architecture that simultaneously learns both the MS bands and the transformation to reconstruct HS spectra from MS signals by analyzing large quantity of HS data. The learned band can be implemented in hardware to obtain an MS sensor that collects data that is best to reconstruct HS spectra using the learned transformation. Using a diverse set of real-world datasets, we show how the proposed approach of optimizing MS bands along with the transformation can drastically increase the reconstruction accuracy. Additionally, we also investigate the prospects of using reconstructed HS spectra for land cover classification.

32

Wang, Sufeng, Yutao Feng, Di Fu, Liang Kong, Hongbo Li, Bin Han, and Feng Lu. "Stratospheric Temperature Observations by Narrow Bands Ultra-High Spectral Resolution Sounder from Nadir-Viewing Satellites." Remote Sensing 15, no. 8 (April 7, 2023): 1967. http://dx.doi.org/10.3390/rs15081967.

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Accurate stratospheric temperature observations are crucial for weather forecasts and climate change studies. This paper discusses a precise measurement method for the stratospheric temperature profile using narrow bands with ultra-high spectral resolution from nadir-viewing satellites. First, the CO2 absorption band around 15 μm is selected as the major sounding source by the calculation and analysis of the temperature Jacobian and the atmospheric molecular spectra. Next, the influence of spectral resolution, spectral range and instrumental noise on the sounding capability is analyzed, and the sounding feasibility of the single spectral band and multiple spectral bands is discussed under the condition that the spaceborne long-wave infrared space heterodyne spectrometer (SHS) is selected as suggested sounder onboard the satellite. Finally, the optimal joint-sounding scheme of narrow bands is proposed. The temperature retrieval and validation show that the joint-sounding of two discontinuous narrow bands can realize the high precision measurement of the stratospheric temperature profile for the given spectral resolution, spectral range, and instrumental noise. When the sounder adopts two narrow bands (the regions of 666.87–676.44 cm−1 and 683.58–693.15 cm−1) and a spectral resolution of 0.03 cm−1, the retrieval accuracy (RMSE) is about 0.9 K over a pressure range of 200 to 0.7 hPa (11.5–50 km). This study will provide technical preparation for high-precision and low-cost satellite sounder design for stratospheric temperature observations.

33

Montes, David, Raquel M. Martínez-Arnáiz, Jesus Maldonado, Juan Roa-Llamazares, Javier López-Santiago, Inés Crespo-Chacón, and Enrique Solano. "Criteria for spectral classification of cool stars using high-resolution spectra." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 598. http://dx.doi.org/10.1017/s1743921307011969.

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We have compiled a large number of optical spectra of cool stars taken with different high-resolution echelle spectrographs (R ≃ 40 000). Many of those are available as spectral libraries (Montes et al. 1997, 1998, 1999, <http://www.ucm.es/info/Astrof/invest/actividad/spectra.html)>.

34

Hood, Callie E., Jonathan J. Fortney, Michael R. Line, and Jacqueline K. Faherty. "Brown Dwarf Retrievals on FIRE!: Atmospheric Constraints and Lessons Learned from High Signal-to-noise Medium-resolution Spectroscopy of a T9 Dwarf." Astrophysical Journal 953, no. 2 (August 1, 2023): 170. http://dx.doi.org/10.3847/1538-4357/ace32e.

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Abstract Brown dwarf spectra offer vital testbeds for our understanding of the chemical and physical processes that sculpt substellar atmospheres. Recently, atmospheric retrieval approaches have been successfully applied to low-resolution (R ∼ 100) spectra of L, T, and Y dwarfs, yielding constraints on the chemical abundances and temperature structures of these atmospheres. Medium-resolution (R ∼ 103) spectra of brown dwarfs offer additional insight, as molecular features are more easily disentangled and the thermal structure of the upper atmosphere is better probed. We present results from a GPU-based retrieval analysis of a high signal-to-noise, medium-resolution (R ∼ 6000) FIRE spectrum from 0.85 to 2.5 μm of the T9 dwarf UGPS J072227.51–054031.2. At 60× higher spectral resolution than previous brown dwarf retrievals, a number of novel challenges arise. We examine the effect of different opacity sources, in particular for CH4. Furthermore, we find that flaws in the data like errors from order stitching can bias our constraints. We compare these retrieval results to those for an R ∼ 100 spectrum of the same object, revealing how constraints on atmospheric abundances and temperatures improve by an order of magnitude or more with increased spectral resolution. In particular, we can constrain the abundance of H2S, which is undetectable at lower spectral resolution. While these medium-resolution retrievals offer the potential of precise, stellar-like constraints on atmospheric abundances (∼0.02 dex), our retrieved radius is unphysically small ( R = 0.50 − 0.01 + 0.01 R Jup), indicating shortcomings with our modeling framework. This work is an initial investigation into brown dwarf retrievals at medium spectral resolution, offering guidance for future ground-based studies and JWST observations.

35

Rountree, Janet, George Sonneborn, and Robert J. Panek. "UV Spectral Classification of B Stars." Symposium - International Astronomical Union 111 (1985): 411–13. http://dx.doi.org/10.1017/s0074180900079092.

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Previous studies of ultraviolet spectral classification have been insufficient to establish a comprehensive classification system for ultraviolet spectra of early-type stars because of inadequate spectral resolution. We have initiated a new study of ultraviolet spectral classification of B stars using high-dispersion IUE archival data. High-dispersion SWP spectra of MK standards and other B stars are retrieved from the IUE archives and numerically degraded to a uniform resolution of 0.25 or 0.50 Å. The spectra (in the form of plots or photowrites) are then visually examined with the aim of setting up a two-dimensional classification matrix. We follow the method used to create the MK classification system for visual spectra. The purpose of this work is to examine the applicability of the MK system (and in particular, the set of standard stars) in the ultraviolet, and to establish classification criteria in this spectral region.

36

Serdyuchenko, A., V. Gorshelev, M. Weber, W. Chehade, and J. P. Burrows. "High spectral resolution ozone absorption cross-sections – Part 2: Temperature dependence." Atmospheric Measurement Techniques 7, no. 2 (February 24, 2014): 625–36. http://dx.doi.org/10.5194/amt-7-625-2014.

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Abstract. We report on the temperature dependence of ozone absorption cross-sections measured in our laboratory in the broad spectral range 213–1100 nm with a spectral resolution of 0.02–0.24 nm (full width at half maximum, FWHM) in the atmospherically relevant temperature range from 193 K to 293 K. The temperature dependence of ozone absorption cross-sections was established using measurements at eleven temperatures. This investigation is superior in terms of spectral range and number of considered temperatures compared to the previous studies. The methodology of the absolute broadband measurements, experimental procedures and spectra processing were described in our companion paper together with the associated uncertainty budget. In this paper, we report in detail on our data below room temperature and compare them with literature data using direct comparisons as well as the standard approach using a quadratic polynomial in temperature fitted to the cross-section data.

37

Jaakkola, P., J. D. Tate, M. Paakkunainen, J. Kauppinen, and P. Saarinen. "Instrumental Resolution Considerations for Fourier Transform Infrared Gas-Phase Spectroscopy." Applied Spectroscopy 51, no. 8 (August 1997): 1159–69. http://dx.doi.org/10.1366/0003702971941683.

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Instrumental resolution has a significant effect on the performance of Fourier transform infrared (FT-IR) spectrometers used for gasphase analysis. Low-resolution FT-IR spectroscopy offers some valuable advantages compared with the traditional high-resolution FT-IR gas-phase spectroscopy, especially in nonlaboratory environments. First, high signal-to-noise ratio (SNR) spectra can be acquired in field conditions without the use of traditional liquid nitrogen-cooled detectors. Second, the dynamic range for quantitative analysis is larger for low-resolution spectroscopy than for high-resolution due to the lower absorbance values and lower noise levels. Third, spectral analysis speed is increased and data storage requirements are substantially reduced. The purpose of this study was to investigate the effect of instrumental resolution on FT-IR gas-phase analysis. The effects of spectral resolution on sensitivity, selectivity, accuracy, precision, spectral overlap, dynamic range, and nonlinearity are separately discussed.

38

Cheng Zhongtao, 成中涛, 刘东 Liu Dong, 刘崇 Liu Chong, 白剑 Bai Jian, 罗敬 Luo Jing, 唐培钧 Tang Peijun, 周雨迪 Zhou Yudi, et al. "Multi-Longitudinal-Mode High-Spectral-Resolution Lidar." Acta Optica Sinica 37, no. 4 (2017): 0401001. http://dx.doi.org/10.3788/aos201737.0401001.

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39

Amin, M. G., and W. J. Williams. "High spectral resolution time-frequency distribution kernels." IEEE Transactions on Signal Processing 46, no. 10 (1998): 2796–804. http://dx.doi.org/10.1109/78.720381.

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40

Xian-Da Zhang and Jie Cheng. "High resolution two-dimensional ARMA spectral estimation." IEEE Transactions on Signal Processing 39, no. 3 (March 1991): 765–70. http://dx.doi.org/10.1109/78.80871.

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41

Clark, Roger N., Trude V. V. King, Matthew Klejwa, Gregg A. Swayze, and Norma Vergo. "High spectral resolution reflectance spectroscopy of minerals." Journal of Geophysical Research 95, B8 (1990): 12653. http://dx.doi.org/10.1029/jb095ib08p12653.

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42

Morrison, M. D., C. W. Bowers, P. D. Feldman, and R. R. Meier. "The EUV dayglow at high spectral resolution." Journal of Geophysical Research 95, A4 (1990): 4113. http://dx.doi.org/10.1029/ja095ia04p04113.

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43

Maraston, C., and G. Strömbäck. "Stellar population models at high spectral resolution." Monthly Notices of the Royal Astronomical Society 418, no. 4 (November 11, 2011): 2785–811. http://dx.doi.org/10.1111/j.1365-2966.2011.19738.x.

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44

Grund, Christian J. "University of Wisconsin High Spectral Resolution Lidar." Optical Engineering 30, no. 1 (1991): 6. http://dx.doi.org/10.1117/12.55766.

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45

Karl, W. C., and H. H. Pien. "High-resolution biosensor spectral peak shift estimation." IEEE Transactions on Signal Processing 53, no. 12 (December 2005): 4631–39. http://dx.doi.org/10.1109/tsp.2005.859215.

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46

Dudhia, Anu, Victoria L. Jay, and Clive D. Rodgers. "Microwindow selection for high-spectral-resolution sounders." Applied Optics 41, no. 18 (June 20, 2002): 3665. http://dx.doi.org/10.1364/ao.41.003665.

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47

van den Branden Lambrecht, Christian, and Mohsine Karrakchou. "Wavelet packets-based high-resolution spectral estimation." Signal Processing 47, no. 2 (November 1995): 135–44. http://dx.doi.org/10.1016/0165-1684(95)00102-6.

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48

Neal, Sharon L. "Comparison of Noniterative Factor Analysis Spectral Resolution Algorithms." Applied Spectroscopy 47, no. 8 (August 1993): 1161–68. http://dx.doi.org/10.1366/0003702934067766.

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The effects of fundamental and ancillary algorithm differences on the performance of three noniterative factor analysis spectral resolution algorithms on noisy and overlapped bilinear matrix-formatted spectral data are evaluated and compared. The evaluation consists of the analysis of simulated fluorescence excitation-emission matrices in which the spectral overlap, noise type, and level were systematically varied. The results indicate that the conventions used to exclude low-intensity, high-noise rows and columns from consideration as component spectra estimates and to choose the first estimates of the component spectra have significant impact on resolution algorithm performance. The results of the application of the algorithms to ideal data are nearly identical; however, there are several distinctions in the performance of the algorithms on noisy data. Verifiable estimates of the component spectra were resolved from data matrices degraded by white and Poisson noise that have signal-to-noise (S/N) ratios above 10 by all three algorithms regardless of the noise level and the degree of spectral overlap. The impact of pink noise was uniformly deleterious at S/N below 15.

49

Everall, Neil, Kevin Davis, Harry Owen, M. J. Pelletier, and Joe Slater. "Density Mapping in Poly(Ethylene Terephthalate) Using a Fiber-Coupled Raman Microprobe and Partial Least-Squares Calibration." Applied Spectroscopy 50, no. 3 (March 1996): 388–93. http://dx.doi.org/10.1366/0003702963906258.

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Partial least-squares (PLS) analysis has been used to calibrate Raman microprobe spectra of poly(ethylene terephthalate) films in terms of density, in order to give insight into changes in crystallinity through the film thickness. The microprobe utilizes a static multiplexed holographic grating to obtain the entire Raman spectrum (-1600-4000 cm-1) in a “single-shot” at ∼ 5-cm−1 resolution. Because there are no moving parts, frequency registration and repeatability are excellent and ideally suited for multivariate calibration. In addition, the high spectral throughput allows the whole spectrum to be collected in a few seconds with high signal-to-noise ratio. With this equipment, cross-validated calibration precisions as low as - 0.0021 g cm−3 were achieved. In this work we considered two ways of removing fluorescence backgrounds prior to carrying out multivariate calibration. The first involved manually fitting a baseline using a polynomial curve and subtracting it. The second approach simply takes the second derivative of the spectrum to attenuate the low-frequency components (i.e., the curved baseline). It was found that either pretreatment gave good calibration precision provided that the resultant spectra were intensity-normalized to correct for variations in laser power, sample alignment, and so on. Surprisingly, it was found that the best precision was obtained by grouping the spectral resolution elements into blocks of eight data points, thereby improving the signal-to-noise but effectively degrading the spectral resolution by a factor of three. This was especially important for the derivative spectra. Alternatively, Savitsky-Golay smoothing of the second derivative data was applied to the same effect but also at the expense of degrading spectral resolution. The implication of this work is that instruments intended for multivariate calibration applications could perhaps be designed to work at rather lower spectral resolutions (but higher signal-to-noise) than might otherwise be considered.

50

Mohammed Noori, Abbas, Sumaya Falih Hasan, Qayssar Mahmood Ajaj, Mustafa Ridha Mezaal, Helmi Z. M. Shafri, and Muntadher Aidi Shareef. "Fusion of Airborne Hyperspectral and WorldView2 Multispectral Images for Detailed Urban Land Cover Classification A case Study of Kuala Lumpur, Malaysia." International Journal of Engineering & Technology 7, no. 4.37 (December 13, 2018): 202. http://dx.doi.org/10.14419/ijet.v7i4.37.24102.

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Detecting the features of urban areas in detail requires very high spatial and spectral resolution in images. Hyperspectral sensors usually offer high spectral resolution images with a low spatial resolution. By contrast, multispectral sensors produce high spatial resolution images with a poor spectral resolution. Therefore, numerous fusion algorithms and techniques have been proposed in recent years to obtain high-quality images with improved spatial and spectral resolutions by sensibly combining the data acquired for the same scene. This work aims to exploit the extracted information from images in an effective way. To achieve this objective, a new algorithm based on transformation was developed. This algorithm primarily depends on the Gram–Schmidt process for fusing images, removing distortions, and improving the appearance of images. Images are first fused by using the Gram–Schmidt pansharpening method. The obtained fused image is utilized in the classification process in different areas by using support vector machine (SVM). The classification result is evaluated using a matrix of errors. The overall accuracy produced from the hyperspectral, multispectral and fused images was 72.33%, 82.83%, and 89.34%, respectively. Results showed that the developed algorithm improved the image enhancement and image fusion. Moreover, the developed algorithm has the ability to produce an imaging product with high spatial resolution and high-quality spectral data.

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