scholarly journals First demonstration of OH suppression in a high-efficiency near-infrared spectrograph

2020 ◽  
Vol 492 (2) ◽  
pp. 2796-2806 ◽  
Author(s):  
S C Ellis ◽  
J Bland-Hawthorn ◽  
J S Lawrence ◽  
A J Horton ◽  
R Content ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Near Infrared ◽  
High Efficiency ◽  
Nir Spectroscopy ◽  
Upper Atmosphere ◽  
Emission Lines ◽  
Spatial And Temporal Variability ◽  
Atmospheric Emission ◽  
Fibre Bragg Gratings ◽  
First Time

ABSTRACT Ground-based near-infrared (NIR) astronomy is severely hampered by the forest of atmospheric emission lines resulting from the rovibrational decay of OH molecules in the upper atmosphere. The extreme brightness of these lines, as well as their spatial and temporal variability, makes accurate sky subtraction difficult. Selectively filtering these lines with OH suppression instruments has been a long standing goal for NIR spectroscopy. We have shown previously the efficacy of fibre Bragg gratings (FBGs) combined with photonic lanterns for achieving OH suppression. Here we report on PRAXIS, a unique NIR spectrograph that is optimized for OH suppression with FBGs. We show for the first time that OH suppression (of any kind) is possible with high overall throughput (18 per cent end-to-end), and provide examples of the relative benefits of OH suppression.

scholarly journals Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

1991 ◽  
Vol 148 ◽  
pp. 205-206 ◽  
Author(s):  
A. Krabbe ◽  
J. Storey ◽  
V. Rotaciuc ◽  
S. Drapatz ◽  
R. Genzel
Keyword(s):  
Spatial Resolution ◽  
Molecular Hydrogen ◽  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Emission Lines ◽  
Resolving Power ◽  
Max Planck ◽  
First Time ◽  
Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

scholarly journals Spatial and temporal variations of winter discharge under climate change: Case study of rivers in European Russia

2015 ◽  
Vol 368 ◽  
pp. 245-250 ◽  
Author(s):  
E. A. Telegina
Keyword(s):  
Temporal Variability ◽  
Climate Changes ◽  
Temporal Variations ◽  
European Russia ◽  
Spatial And Temporal Variability ◽  
Water Runoff ◽  
Underground Waters ◽  
Winter Runoff ◽  
First Time

Abstract. An important problem in hydrology is the re-evaluation of the current resources of surface and underground waters in the context of ongoing climate changes. The main feature of the present-day changes in water regime in the major portion of European Russia (ER) is the substantial increase in low-water runoff, especially in winter. In this context, some features of the spatial–temporal variations of runoff values during the winter low-water period are considered. Calculations showed that the winter runoff increased at more than 95% of hydrological gauges. Changes in the minimum and average values of runoff during winter low-water period and other characteristics are evaluated against the background of climate changes in the recent decades. The spatial and temporal variability of winter runoff in European Russia is evaluated for the first time.

scholarly journals Application of VIS/NIR Spectroscopy and SDAE-NN Algorithm for Predicting the Cold Storage Time of Salmon

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ting Wu ◽  
Nan Zhong ◽  
Ling Yang
Keyword(s):  
Neural Network ◽  
Cold Storage ◽  
Storage Time ◽  
Near Infrared ◽  
High Efficiency ◽  
Back Propagation ◽  
Nir Spectroscopy ◽  
Back Propagation Neural Network ◽  
Least Squares Regression ◽  
Test Sets

The cold storage time of salmon has a significant impact on its freshness, which is an important factor for consumers to evaluate the quality of salmon. The efficient, accurate, and convenient protocol is urgent to appraise the freshness for quality checking. In this paper, the ability of visible/near-infrared (VIS/NIR) spectroscopy was evaluated to predict the cold storage time of salmon meat and skin, which were stored at low-temperature box for 0~12 days. Meanwhile, a double-layer stacked denoising autoencoder neural network (SDAE-NN) algorithm was introduced to establish the prediction model without spectral pre-preprocessing. The results showed that, compared with the common methods such as partial least squares regression (PLSR) and back propagation neural network (BP-NN), the SDAE-NN method had a better performance due to its high efficiency in decreasing noise and optimizing the initial weights. The determination coefficient of test sets (R2test) and root mean square error of test sets (RMSEP) have been calculated based on SDAE-NN, for the salmon meat (skin), the R2test can reach 0.98 (0.92), and the RMSEP can reach 0.93 (1.75), respectively. It is highlighted that the algorithm is efficient and accurate and that the salmon meat would be more suitable for predicting freshness than the salmon skin. VIS/NIR spectroscopy combined with the SDAE-NN algorithm can be widely used to predict the freshness of various agricultural products.

THE NEAR INFRARED SPECTRUM OF THE NIGHT AIRGLOW OBSERVED FROM HIGH ALTITUDE

1964 ◽  
Vol 42 (6) ◽  
pp. 1037-1045 ◽  
Author(s):  
H. P. Gush ◽  
H. L. Buijs
Keyword(s):  
Infrared Spectrum ◽  
Emission Spectrum ◽  
High Altitude ◽  
Electronic Transition ◽  
Near Infrared ◽  
Michelson Interferometer ◽  
Infrared Emission ◽  
Upper Atmosphere ◽  
Transition Formula ◽  
First Time

The infrared emission spectrum of the upper atmosphere between 1.2 and 2.5 microns has been measured at night by means of a Michelson interferometer carried to an altitude of 90,000 feet by a balloon. The complete Δν = 2 sequence of rotation–vibration OH bands has been observed at a resolution sufficient to resolve the rotational structure. The (0, 0) band of the electronic transition [Formula: see text] of oxygen at 1.27 microns has been observed in the night-sky spectrum for the first time. Its brightness is comparable with that of the (4, 2) OH band at 1.6 microns.

scholarly journals Near-infrared emission lines trace the state-independent accretion disc wind of the black hole transient MAXI J1820+070

2020 ◽  
Vol 640 ◽  
pp. L3 ◽  
Author(s):  
J. Sánchez-Sierras ◽  
T. Muñoz-Darias
Keyword(s):  
Black Hole ◽  
Emission Line ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Accretion Disc ◽  
Emission Lines ◽  
X Rays ◽  
Data Set ◽  
Soft State ◽  
Hard State

The black hole transient MAXI J1820+070 displayed optical P Cyg profiles and other wind-related emission line features during the hard state of its discovery outburst. We present near-infrared (NIR) spectroscopy covering the different accretion states of the system during this event. Our eight-epoch data set (VLT/X-shooter) reveals strong variability in the properties of the NIR emission lines. This includes absorption troughs and extended emission line wings with kinetic properties that are remarkably similar to those inferred from the wind signatures observed in optical emission lines, indicating that they most likely trace the same accretion disc wind. Unlike the optical features, these NIR signatures are not exclusive of the hard state, as they are also witnessed across the soft state with similar observational properties. This supports the presence of a relatively steady outflow during the entire outburst of the system, and it represents the first detection of an accretion disc wind in a black hole soft state at energies other than X-rays. We discuss the visibility of the wind as a function of the spectral band and the potential of NIR spectroscopy for wind studies, in particular during luminous accretion phases.

scholarly journals Oxygen abundances of zCOSMOS galaxies at z ∼ 1.4 based on five lines and implications for the fundamental metallicity relation

2014 ◽  
Vol 10 (S309) ◽  
pp. 281-282 ◽  
Author(s):  
Christian Maier ◽  
Simon J. Lilly ◽  
Bodo L. Ziegler ◽  
Keyword(s):  
Gas Phase ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Stellar Mass ◽  
Emission Lines ◽  
Star Forming

AbstractA relation between the stellar mass M and the gas-phase metallicity Z of galaxies, the MZR, is observed up to higher redshifts. It is a matter of debate, however, if the SFR is a second parameter in the MZR. To explore this issue at z > 1, we used VLT-SINFONI near-infrared (NIR) spectroscopy of eight zCOSMOS galaxies at 1.3 < z < 1.4 to measure the strengths of four emission lines: Hβ, [OIII]λ5007, Hα, and [NII]λ6584, additional to [OII]λ3727 measured from VIMOS. We derive reliable O/H metallicities based on five lines, and also SFRs from extinction corrected Hα measurements. We find that the MZR of these star-forming galaxies at z ≈ 1.4 is lower than the local SDSS MZR by a factor of three to five, a larger change than reported in the literature using [NII]/Hα-based metallicities from individual and stacked spectra. Correcting N2-based O/Hs using recent results by Newman et al. (2014), also the larger FMOS sample at z ∼ 1.4 of Zahid et al. (2014) shows a similar evolution of the MZR like the zCOSMOS objects. These observations seem also in agreement with a non-evolving FMR using the physically motivated formulation of the FMR from Lilly et al. (2013).

scholarly journals Application of near-infrared spectroscopy technology in the complex fermentation system to achieve high-efficiency production

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Chen Yang ◽  
Chen Lingli ◽  
Guo Meijin ◽  
Li Xu ◽  
Liu jinsong ◽  
...  
Keyword(s):  
Real Time ◽  
Fermentation Process ◽  
Near Infrared ◽  
High Efficiency ◽  
Prediction Models ◽  
Nir Spectroscopy ◽  
Environmental Parameters ◽  
Inhomogeneous System ◽  
Least Squares Regression ◽  
Experiment Platform

AbstractThe fermentation process is dynamically changing, and the metabolic status can be grasped through real-time monitoring of environmental parameters. In this study, a real-time and on-line monitoring experiment platform for substrates and products detection was developed based on non-contact type near-infrared (NIR) spectroscopy technology. The prediction models for monitoring the fermentation process of lactic acid, sophorolipids (SLs) and sodium gluconate (SG) were established based on partial least-squares regression and internal cross-validation methods. Through fermentation verification, the accuracy and precision of the NIR model for the complex fermentation environments, different rheological properties (uniform system and multi-phase inhomogeneous system) and different parameter types (substrate, product and nutrients) have good applicability, and R2 was greater than 0.98, exhibiting a good linear relationship. The root mean square error of prediction shows that the model has high credibility. Through the control of appropriate glucose concentration in SG fermentation as well as glucose and oil concentrations SLs fermentation by NIR model, the titers of SG and SLs were increased to 11.8% and 26.8%, respectively. Although high cost of NIR spectrometer is a key issue for its wide application in an industrial scale. This work provides a basis for the application of NIR spectroscopy in complex fermentation systems.

scholarly journals Simulated NIR spectra as sensitive markers of the structure and interactions in nucleobases

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Krzysztof B. Beć ◽  
Justyna Grabska ◽  
Yukihiro Ozaki ◽  
Mirosław A. Czarnecki ◽  
Christan W. Huck
Keyword(s):  
Near Infrared ◽  
Plane Deformation ◽  
Vibrational Analysis ◽  
Nir Spectroscopy ◽  
Full Potential ◽  
Molecular Models ◽  
Deformation Bands ◽  
Near Ir ◽  
Out Of Plane ◽  
First Time

AbstractNear-infrared (near-IR; NIR) spectroscopy is continuously advancing in biophysical and biochemical fields of investigation. For instance, recent progresses in NIR hyperspectral imaging of biological systems may be noted. However, interpretation of NIR bands for biological samples is difficult and creates a considerable barrier in exploring the full potential of NIR spectroscopy in bioscience. For this reason, we carried out a systematic study of NIR spectra of adenine, cytosine, guanine, and thymine in polycrystalline state. Interpretation of NIR spectra of these nucleobases was supported by anharmonic vibrational analysis using Deperturbed Vibrational Second-Order Perturbation Theory (DVPT2). A number of molecular models of nucleobases was applied to study the effect of the inter-molecular interactions on the NIR spectra. The accuracy of simulated NIR spectra appears to depend on the intra-layer interactions; in contrast, the inter-layer interactions are less influential. The best results were achieved by combining the simulated spectra of monomers and dimers. It is of particular note that in-plane deformation bands are far more populated than out-of-plane ones and the importance of ring modes is relatively small. This trend is in contrast to that observed in mid-IR region. As shown, the local, short-range chemical neighborhood of nucleobase molecules influence their NIR spectra more considerably. This suggests that NIR spectra are more sensitive probe of the nucleobase pairing than mid-IR ones. The obtained results allow, for the first time, to construct a frequency correlation table for NIR spectra of purines and pyrimidines.

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