Spectrometer Using superconductor MIxer Receiver (SUMIRE) for laboratory submillimeter spectroscopy

Abstract Recent spectroscopic observations by sensitive radio telescopes require accurate molecular spectral line frequencies to identify molecular species in a forest of lines detected. To measure rest frequencies of molecular spectral lines in the laboratory, an emission-type millimeter and submillimeter-wave spectrometer utilizing state-of-the-art radio-astronomical technologies is developed. The spectrometer is equipped with a 200 cm glass cylinder cell, a two-sideband (2SB) superconductor-insulator-superconductor (SIS) receiver in the 230 GHz band, and wide-band auto-correlation digital spectrometers. By using the four 2.5 GHz digital spectrometers, a total instantaneous bandwidth of the 2SB SIS receiver of 8 GHz can be covered with a frequency resolution of 88.5 kHz. Spectroscopic measurements of CH3CN and HDO are carried out in the 230 GHz band so as to examine the frequency accuracy, stability, sensitivity, as well as the intensity calibration accuracy of our system. As for the result of CH3CN, we confirm that the frequency accuracy for lines detected with sufficient signal-to-noise ratio is better than 1 kHz, when the high-resolution spectrometer having a channel resolution of 17.7 kHz is used. In addition, we demonstrate the capability of this system by spectral scan measurement of CH3OH from 216 GHz to 264 GHz. We assign 242 transitions of CH3OH, 51 transitions of 13CH3OH, and 21 unidentified emission lines for 295 detected lines. Consequently, our spectrometer demonstrates sufficient sensitivity, spectral resolution, and frequency accuracy for in-situ experimental-based rest frequency measurements of spectral lines for various molecular species.

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Transient phase fraction and dislocation density estimation from in-situ X-ray diffraction data with a low signal-to-noise ratio using a Bayesian approach to the Rietveld analysis

Materials Characterization ◽

10.1016/j.matchar.2020.110860 ◽

2020 ◽

pp. 110860

Author(s):

Manfred Wiessner ◽

Paul Angerer ◽

Sybrand van der Zwaag ◽

Ernst Gamsjäger

Keyword(s):

Dislocation Density ◽

Density Estimation ◽

Diffraction Data ◽

Signal To Noise Ratio ◽

Rietveld Analysis ◽

Transient Phase ◽

X Ray Diffraction ◽

Signal To Noise ◽

X Ray

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Mesoscopic simulations of the in situ NMR spectra of porous carbon based supercapacitors: Electronic structure and adsorbent reorganisation effects

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02130c ◽

2021 ◽

Author(s):

Anagha Sasikumar ◽

Anouar Belhboub ◽

Camille Bacon ◽

Alexander C. Forse ◽

John Griffin ◽

...

Keyword(s):

Electronic Structure ◽

Nmr Spectroscopy ◽

Molecular Species ◽

Porous Carbon ◽

Nmr Spectra ◽

Charge Storage ◽

In Situ Nmr Spectroscopy ◽

In Situ Nmr ◽

Carbon Based

In situ NMR spectroscopy is a powerful technique to investigate charge storage mechanisms in carbon-based supercapacitors thanks to its ability to distinguish ionic and molecular species adsorbed in the porous...

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Detected Changes in Precipitation Extremes at Their Native Scales Derived from In Situ Measurements

Journal of Climate ◽

10.1175/jcli-d-19-0077.1 ◽

2019 ◽

Vol 32 (23) ◽

pp. 8087-8109 ◽

Cited By ~ 2

Author(s):

Mark D. Risser ◽

Christopher J. Paciorek ◽

Travis A. O’Brien ◽

Michael F. Wehner ◽

William D. Collins

Keyword(s):

Extreme Precipitation ◽

Seasonal Changes ◽

Signal To Noise Ratio ◽

Statistical Technique ◽

In Situ Measurements ◽

Absolute Sense ◽

Underlying Causes ◽

Changes Over Time ◽

Future Work

Abstract The gridding of daily accumulated precipitation—especially extremes—from ground-based station observations is problematic due to the fractal nature of precipitation, and therefore estimates of long period return values and their changes based on such gridded daily datasets are generally underestimated. In this paper, we characterize high-resolution changes in observed extreme precipitation from 1950 to 2017 for the contiguous United States (CONUS) based on in situ measurements only. Our analysis utilizes spatial statistical methods that allow us to derive gridded estimates that do not smooth extreme daily measurements and are consistent with statistics from the original station data while increasing the resulting signal-to-noise ratio. Furthermore, we use a robust statistical technique to identify significant pointwise changes in the climatology of extreme precipitation while carefully controlling the rate of false positives. We present and discuss seasonal changes in the statistics of extreme precipitation: the largest and most spatially coherent pointwise changes are in fall (SON), with approximately 33% of CONUS exhibiting significant changes (in an absolute sense). Other seasons display very few meaningful pointwise changes (in either a relative or absolute sense), illustrating the difficulty in detecting pointwise changes in extreme precipitation based on in situ measurements. While our main result involves seasonal changes, we also present and discuss annual changes in the statistics of extreme precipitation. In this paper we only seek to detect changes over time and leave attribution of the underlying causes of these changes for future work.

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Ultrastructural visualization of cytoskeletal mRNAs and their associated proteins using double-label in situ hybridization.

The Journal of Cell Biology ◽

10.1083/jcb.108.6.2343 ◽

1989 ◽

Vol 108 (6) ◽

pp. 2343-2353 ◽

Cited By ~ 105

Author(s):

R H Singer ◽

G L Langevin ◽

J B Lawrence

Keyword(s):

In Situ Hybridization ◽

High Resolution ◽

Colloidal Gold ◽

Messenger Rna ◽

Signal To Noise Ratio ◽

Simultaneous Detection ◽

Gold Particles ◽

Rna Molecules ◽

Nucleic Acid Molecule

We have been able to visualize cytoskeletal messenger RNA molecules at high resolution using nonisotopic in situ hybridization followed by whole-mount electron microscopy. Biotinated cDNA probes for actin, tubulin, or vimentin mRNAs were hybridized to Triton-extracted chicken embryo fibroblasts and myoblasts. The cells were then exposed to antibodies against biotin followed by colloidal gold-conjugated antibodies and then critical-point dried. Identification of mRNA was possible using a probe fragmented to small sizes such that hybridization of several probe fragments along the mRNA was detected as a string of colloidal gold particles qualitatively and quantitatively distinguishable from nonspecific background. Extensive analysis showed that when eight gold particles were seen in this iterated array, the signal to noise ratio was greater than 30:1. Furthermore, these gold particles were colinear, often spiral, or circular suggesting detection of a single nucleic acid molecule. Antibodies against actin, vimentin, or tubulin proteins were used after in situ hybridization, allowing simultaneous detection of the protein and its cognate message on the same sample. This revealed that cytoskeletal mRNAs are likely to be extremely close to actin protein (5 nm or less) and unlikely to be within 20 nm of vimentin or tubulin filaments. Actin mRNA was found to be more predominant in lamellipodia of motile cells, confirming previous results. These results indicate that this high resolution in situ hybridization approach is a powerful tool by which to investigate the association of mRNA with the cytoskeleton.

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A Novel Symbol Rate Estimation Algorithm for Phase Modulating Signals in Wireless Communications

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.443.392 ◽

2013 ◽

Vol 443 ◽

pp. 392-396

Author(s):

Peng Zhou ◽

Chi Sheng Li

Keyword(s):

Signal To Noise Ratio ◽

Estimation Algorithm ◽

Frequency Resolution ◽

Phase Shift Keying ◽

Phase Jump ◽

Rate Estimation ◽

Awgn Channel ◽

Symbol Rate ◽

Shift Keying ◽

Simulation Results

In this paper, we proposed a new symbol rate estimation algorithm for phase shift keying (PSK) and qua drawtube amplitude modulation (QAM) signals in AWGN channel First we constructe a delay-multiplied signal, from which we obtaine the modulated information. Then we calculated the instantaneous autocorrelation of the delay-multiplied signal to pick out the phase jump. To eliminate the restriction of frequency resolution in fast Fourier transform, we performed a Chirp-Z transform to find out the exact spectral line which represente the symbol rate of the signal to be analyzed. Compared with the existing algorithms, it is a simple solution that has a better performance and accuracy in low signal-to-noise-ratio channel conditions. Simulation results show that the probability of relative estimating deviation below 0.1% reaches 100% and the average and standard variance of absolute estimation deviation are at the magnitude of 10-2 when SNR is over 2dB.

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Enhancement of Radar Imagery by Maximum Entropy Processing

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/107118137702100315 ◽

1977 ◽

Vol 21 (3) ◽

pp. 241-243 ◽

Cited By ~ 3

Author(s):

Clanton E. Mancill

Keyword(s):

Maximum Entropy ◽

Signal To Noise Ratio ◽

Super Resolution ◽

Doppler Frequency ◽

Frequency Measurement ◽

Entropy Method ◽

Frequency Resolution ◽

Sampled Data ◽

Maximum Entropy Spectrum ◽

Using Data

The maximum entropy spectrum (MES), a sampled data power spectrum estimator, is applied to the enhancement of imagery obtained by synthetic array radar (SAR) imaging systems. MES offers better frequency resolution than conventional Fourier transform methods for certain signal classes. Since azimuth ground resolution in SAR systems is obtained by doppler frequency measurement of the radar return, the method is capable of enhancing the resolution of SAR maps. The principal signal requirement is adequate signal-to-noise ratio. The maximum entropy method has been tested using data obtained by the Hughes FLAMR radar system. The super-resolution capabilities of the method are demonstrated using FLAMR images of corner reflector arrays.

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Structural Quality And Electrical Behavior Of Epitaxial High-κ Y2O3 / Si(001)

MRS Proceedings ◽

10.1557/proc-745-n9.10/t7.10 ◽

2002 ◽

Vol 745 ◽

Author(s):

G. Vellianitis ◽

G. Apostolopoulos ◽

A. Dimoulas ◽

K. Argyropoulos ◽

B. Mereu ◽

...

Keyword(s):

Leakage Current ◽

Wide Band ◽

Amorphous Layer ◽

Ex Situ ◽

Structural Quality ◽

Wide Band Gap ◽

Annealing Temperatures ◽

Grown Sample ◽

Transistor Fabrication

ABSTRACTY2O3 thin films were grown directly on Si (001) by MBE and annealed in-situ under UHV at various annealing temperatures. The samples were investigated in-situ by RHEED and ex-situ by HRTEM. A 7 to 15 Å thick non-uniform interfacial amorphous layer is observed in the as-grown sample. After annealing at 490°C under UHV for 30 minutes the amorphous layer is reduced and a sharp Y2O3/Si interface is obtained. At higher annealing temperatures, YSi2 islands start to form at the Y2O3/Si interface. I-V measurements performed on generic MIS structures show that the annealed samples exhibit higher leakage current density than the as-grown sample, due to reduction of the wide band gap interfacial layer. Leakage current densities in annealed samples remain below 1A/cm2, which is acceptable for future high-κ transistor fabrication.

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Spectrum Sensing in Cognitive Radio using Frequency Domain

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.b4915.129219 ◽

2019 ◽

Vol 9 (2) ◽

pp. 3475-3477

Keyword(s):

Cognitive Radio ◽

Frequency Domain ◽

Spectrum Sensing ◽

Bandwidth Allocation ◽

Dynamic Spectrum Access ◽

Signal To Noise Ratio ◽

Wide Band ◽

Energy Detection ◽

Secondary Users ◽

Sensing Applications

An efficient bandwidth allocation and dynamic bandwidth access away from its previous limits is referred as cognitive radio (CR).The limited spectrum with inefficient usage requires the advances of dynamic spectrum access approach, where the secondary users are authorized to utilize the unused temporary licensed spectrum. For this reason it is essential to analyze the absence/presence of primary users for spectrum usage. So spectrum sensing is the main requirement and developed to sense the absence/ presence of a licensed user. This paper shows the design model of energy detection based spectrum sensing in frequency domain utilizing Binary Symmetric Channel (BSC) ,Additive white real Gaussian channel (AWGN), Rayleigh fading channel users for 16-Quadrature Amplitude Modulation(QAM) which is utilized for the wide band sensing applications at low Signal to noise Ratio(SNR) level to reduce the false error identification. The spectrum sensing techniques has least computational complexity. Simulink model for the energy detection based spectrum sensing using frequency domain in MATLAB 2014a.

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The first data release of LAMOST low-resolution single-epoch spectra

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/21/10/249 ◽

2021 ◽

Vol 21 (10) ◽

pp. 249

Author(s):

Zhong-Rui Bai ◽

Hao-Tong Zhang ◽

Hai-Long Yuan ◽

Dong-Wei Fan ◽

Bo-Liang He ◽

...

Keyword(s):

Radial Velocity ◽

Signal To Noise Ratio ◽

Time Lag ◽

Spectral Lines ◽

Low Resolution ◽

Signal To Noise ◽

Data Release ◽

Repeat Exposure ◽

Noise Ratio ◽

Single Epoch

Abstract LAMOST Data Release 5, covering ∼17 000 deg2 from –10° to 80° in declination, contains 9 million co-added low-resolution spectra of celestial objects, each spectrum combined from repeat exposure of two to tens of times during Oct 2011 to Jun 2017. In this paper, we present the spectra of individual exposures for all the objects in LAMOST Data Release 5. For each spectrum, the equivalent width of 60 lines from 11 different elements are calculated with a new method combining the actual line core and fitted line wings. For stars earlier than F type, the Balmer lines are fitted with both emission and absorption profiles once two components are detected. Radial velocity of each individual exposure is measured by minimizing χ 2 between the spectrum and its best template. The database for equivalent widths of spectral lines and radial velocities of individual spectra are available online. Radial velocity uncertainties with different stellar type and signal-to-noise ratio are quantified by comparing different exposure of the same objects. We notice that the radial velocity uncertainty depends on the time lag between observations. For stars observed in the same day and with signal-to-noise ratio higher than 20, the radial velocity uncertainty is below 5km s−1, and increases to 10 km s−1 for stars observed in different nights.

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