scholarly journals Measurement of CO2 by Wavelength Modulated Reinjection Off-Axis Integrated Cavity Output Spectroscopy at 2 μm

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1247
Author(s):  
Zihao Yuan ◽  
Yinbo Huang ◽  
Xingji Lu ◽  
Jun Huang ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Signal Intensity ◽  
Performance Enhancement ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Co2 Concentration ◽  
Trace Gas ◽  
Cavity Output ◽  
Average System ◽  
Long Time ◽  
Gas Measurements

A high sensitivity wavelength modulated reinjection off-axis integrated cavity output spectroscopy (WM-RE-OA-ICOS) experimental setup was built at a 2 μm band. On the basis of an off-axis integrated output spectroscopy (OA-ICOS), combined with an optical reinjection (RE) approach to improve signal intensity, and wavelength modulation spectroscopy (WMS) to improve the signal-to-noise ratio (SNR) of the system, the experimental study of trace CO2 with high sensitivity was carried out using the setup. The performance was compared and evaluated, and the results show that: Compared with the OA-ICOS, the wavelength modulated reinjection OA-ICOS enhanced the signal intensity by 6.3 times, and the SNR increased 7.2 times from 179 to 1288. The Allan variance results showed that the detection limit of the system is 0.35 ppm when the average system time is 230 s. The setup was used to measure the indoor CO2 concentration for a long time (22 h), and the measured results were in line with the actual concentration change. The proposed method shows good performance enhancement for the OA-ICOS system in trace gas measurements.

scholarly journals Performance Enhancement Methods for the Distributed Acoustic Sensors Based on Frequency Division Multiplexing

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 617 ◽  
Author(s):  
Yanzhu Hu ◽  
Zhen Meng ◽  
Mohammadmasoud Zabihi ◽  
Yuanyuan Shan ◽  
Siyi Fu ◽  
...  
Keyword(s):  
Performance Enhancement ◽  
Signal To Noise Ratio ◽  
Dead Zone ◽  
High Sensitivity ◽  
Time Domain Reflectometry ◽  
System Structure ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Rayleigh Backscattering ◽  
Sensing System

The last years have witnessed the wide application of Distributed Acoustic Sensor (DAS) systems in several fields, such as submarine cable monitoring, seismic wave detection, structural health monitoring, etc. Due to their distributed measurement ability and high sensitivity, DAS systems can be employed as a promising tool for the phase sensitive optical time domain reflectometry (Φ-OTDR). However, it is also well-known that the traditional Φ-OTDR system suffers from Rayleigh backscattering (RBS) fading effects, which induce dead zones in the measurement results. Worse still, in practice it is difficult to achieve the optimum matching between spatial resolution (SR) and signal to noise ratio (SNR). Further, the overall frequency response range (FRR) of the traditional Φ-OTDR is commonly limited by the length of the fiber in order to prevent RBS signals from overlapping with each other. Additionally, it is usually difficult to reconstruct high frequency vibration signals accurately for long range monitoring. Aiming at solving these problems, we introduce frequency division multiplexing (FDM) that makes it easier to improve the system performance with less system structure changes. We propose several novel Φ-OTDR schemes based on Frequency Division Multiplexing (FDM) technology to solve the above problems. Experimental results showed that the distortion induced by fading effects could be suppressed to 1.26%; when the SR of Φ-OTDR is consistent with the length of the vibration region, the SNR of the sensing system is improved by 3 dB compared to the average SNR with different SRs; vibration frequencies up to 440 kHz have been detected along 330 m artificial microstructures. Thus, the proposed sensing system offers a promising solution for the performance enhancement of DAS systems that could achieve high SNR, broadband FRR and dead zone-free measurements at the same time.

scholarly journals Performance Enhancement of the Location and Recognition of a Φ-OTDR System Using CEEMDAN-KL and AMNBP

2020 ◽  
Vol 10 (9) ◽  
pp. 3047
Author(s):  
Yanzhu Hu ◽  
Zhen Meng ◽  
Xinbo Ai ◽  
Yu Hu ◽  
Yixin Zhang ◽  
...  
Keyword(s):  
Performance Enhancement ◽  
Signal To Noise Ratio ◽  
Dead Zone ◽  
Recognition Rate ◽  
High Sensitivity ◽  
Ensemble Empirical Mode Decomposition ◽  
Time Domain Reflectometry ◽  
Long Distance ◽  
Practical Applications ◽  
Leibler Divergence

It is commonly known that for characteristics, such as long-distance, high-sensitivity, and full-scale monitoring, phase-sensitive optical time-domain reflectometry (Φ-OTDR) has developed rapidly in many fields, especially with the arrival of 5G. Nevertheless, there are still some problems obstructing the application for practical environments. First, the fading effect leads to some results falling into the dead zone, which cannot be demodulated effectively. Second, because of the high sensitivity, the Φ-OTDR system is easy to be interfered with by strong noise in practical environments. Third, the large volume of data caused by the fast responses require a lot of calculations. All the above problems hinder the performance of Φ-OTDR in practical applications. This paper proposes an integration method based on a complete ensemble empirical mode decomposition with adaptive noise and Kullback–Leibler divergence (CEEMDAN-KL) and an adaptive moving neighbor binary pattern (AMNBP) to enhance the performance of Φ-OTDR. CEEMDAN-KL improved the signal characteristics in low signal-to-noise ratio (SNR) conditions. AMNBP optimized the location and recognition via a high calculation efficiency. Experimental results show that the average recognition rate of four kinds of events reached 94.03% and the calculation efficiency increased by 20.0%, which show the excellent performance of Φ-OTDR regarding location and recognition in practical environments.

Mechanical thumb pain in a systemic sclerosis patient: simple first carpometacarpal osteoarthritis?

Rheumatology ◽  
2021 ◽  
Author(s):  
Guillaume LARID ◽  
Pier-Olivier DUBOE ◽  
Jean-Denis LAREDO ◽  
Elisabeth GERVAIS
Keyword(s):  
Systemic Sclerosis ◽  
Signal Intensity ◽  
Topoisomerase I ◽  
Joint Space ◽  
Carpometacarpal Joint ◽  
Cross Sectional ◽  
First Carpometacarpal Joint ◽  
Provide Pain Relief ◽  
Long Time ◽  
Carpometacarpal Osteoarthritis

Abstract A 70-year-old female patient treated with methotrexate for diffuse cutaneous systemic sclerosis (SSc) came up with mechanical pain over the left thumb for several months. SSc was diagnosed based on a clinical picture associating puffy fingers, skin sclerosis, wrist arthralgia, pulmonary hypertension, presence of antinuclear factors and antibodies against Topoisomerase-I. Her complaint was attributed to first carpometacarpal joint osteoarthritis and treated with orthesis, which did not provide pain relief after 5 months of regular use. Hand radiograph showed first carpometacarpal arthropathy with joint space narrowing and marked sclerosis of the first proximal metacarpal (A). MRI showed an area of very low signal intensity on T1- and T2-weighted images (B) within the proximal metacarpal, distal trapezium and medial joint recess surrounded by bone marrow edema. Mild peripheral enhancement was present after gadolinium injection. CT-scan (C) showed that the low signal intensity material visible at MRI consisted of calcium. These aspects are suggestive of scleroderma arthropathy rather than common first carpometacarpal osteoarthritis. Though involvement of the first carpometacarpal joint is long time known in SSc [1], it remains exceptional when looking at cross-sectional studies [2]. Carefully analyzing imaging exams is the key point in order not to miss this rare scleroderma feature.

scholarly journals Signal Intensity of Stem Diameter Variation for the Diagnosis of Drip Irrigation Water Deficit in Grapevine

Horticulturae ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 154
Author(s):  
Chen Ru ◽  
Xiaotao Hu ◽  
Wene Wang ◽  
Hui Ran ◽  
Tianyuan Song ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Signal Intensity ◽  
Signal To Noise Ratio ◽  
Water Status ◽  
Stem Diameter ◽  
Vegetative Stage ◽  
Signal To Noise ◽  
Diameter Variation ◽  
Expansion Stage ◽  
Noise Ratio

Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study describes a study on stem diameter variations of grapevine planted in a greenhouse in the semi-arid area of Northwest China. In order to determine the applicability of signal intensity of stem diameter variation to evaluate the water status of grapevine and soil. The results showed that the relative variation curve of the grapevine stem diameter from the vegetative stage to the fruit expansion stage showed an overall increasing trend. The correlations of MDS (maximum daily shrinkage) and DI (daily increase) with meteorological factors were significant (p < 0.05), and the correlations with SWP, RWC and soil moisture were weak. Although MDS and DI can diagnose grapevine water status in time, SIMDS and SIDI have the advantages of sensitivity and signal intensity compared with other indicators. Compared with MDS and DI, the R2 values of the regression equations of SIMDS and SIDI with SWP and RWC were high, and the correlation reached a very significant level (p < 0.01). Thus, SIMDS and SIDI are more suitable for the diagnosis of grapevine water status. The SIMDS peaked at the fruit expansion stage, reaching 0.957–1.384. The signal-to-noise ratio of SIDI was higher than that of MDS across the three treatments at the vegetative stage. The value and signal-to-noise ratio of SIDI at the flowering stage were similar to those of SIMDS, while the correlation between SIDI and the soil moisture content was higher than that of SIMDS. It can be concluded that that SIDI is suitable as an indicator of water status of grapevine and soil during the vegetative and flowering stages. In addition, the signal-to-noise ratio of SIMDS during the fruit expansion and mature stages was significantly higher than that of SIDI. Therefore, SIMDS is suitable as an indicator of the moisture status of grapevine and soil during the fruit expansion and mature stages. In general, SIMDS and SIDI were very good predictors of the plant water status during the growth stage and their continuous recording offers the promising possibility of their use in automatic irrigation scheduling in grapevine.

scholarly journals The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 813
Author(s):  
Magdalena Świądro ◽  
Paweł Stelmaszczyk ◽  
Irena Lenart ◽  
Renata Wietecha-Posłuszny
Keyword(s):  
Date Rape ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Heroin Addiction ◽  
Assisted Extraction ◽  
Low Concentrations ◽  
High Concentrations ◽  
Rosé Wine ◽  
Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

scholarly journals Mid-infrared photoacoustic gas monitoring driven by a gas-filled hollow-core fiber laser

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yazhou Wang ◽  
Yuyang Feng ◽  
Abubakar I. Adamu ◽  
Manoj K. Dasa ◽  
J. E. Antonio-Lopez ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Laser Source ◽  
High Signal ◽  
Mid Infrared ◽  
Raman Fiber Laser ◽  
Custom Made ◽  
Core Fiber ◽  
Detection Technologies

AbstractDevelopment of novel mid-infrared (MIR) lasers could ultimately boost emerging detection technologies towards innovative spectroscopic and imaging solutions. Photoacoustic (PA) modality has been heralded for years as one of the most powerful detection tools enabling high signal-to-noise ratio analysis. Here, we demonstrate a novel, compact and sensitive MIR-PA system for carbon dioxide (CO2) monitoring at its strongest absorption band by combining a gas-filled fiber laser and PA technology. Specifically, the PA signals were excited by a custom-made hydrogen (H2) based MIR Raman fiber laser source with a pulse energy of ⁓ 18 μJ, quantum efficiency of ⁓ 80% and peak power of ⁓ 3.9 kW. A CO2 detection limit of 605 ppbv was attained from the Allan deviation. This work constitutes an alternative method for advanced high-sensitivity gas detection.

scholarly journals Soil gas probes for monitoring trace gas messengers of microbial activity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Joseph R. Roscioli ◽  
Laura K. Meredith ◽  
Joanne H. Shorter ◽  
Juliana Gil-Loaiza ◽  
Till H. M. Volkmann
Keyword(s):  
Microbial Activity ◽  
Soil Heterogeneity ◽  
Soil Gas ◽  
Microbial Processes ◽  
Trace Gas ◽  
Soil Microbiome ◽  
Sampling System ◽  
Site Specific ◽  
Gas Measurements ◽  
Subsurface Monitoring

AbstractSoil microbes vigorously produce and consume gases that reflect active soil biogeochemical processes. Soil gas measurements are therefore a powerful tool to monitor microbial activity. Yet, the majority of soil gases lack non-disruptive subsurface measurement methods at spatiotemporal scales relevant to microbial processes and soil structure. To address this need, we developed a soil gas sampling system that uses novel diffusive soil probes and sample transfer approaches for high-resolution sampling from discrete subsurface regions. Probe sampling requires transferring soil gas samples to above-ground gas analyzers where concentrations and isotopologues are measured. Obtaining representative soil gas samples has historically required balancing disruption to soil gas composition with measurement frequency and analyzer volume demand. These considerations have limited attempts to quantify trace gas spatial concentration gradients and heterogeneity at scales relevant to the soil microbiome. Here, we describe our new flexible diffusive probe sampling system integrated with a modified, reduced volume trace gas analyzer and demonstrate its application for subsurface monitoring of biogeochemical cycling of nitrous oxide (N2O) and its site-specific isotopologues, methane, carbon dioxide, and nitric oxide in controlled soil columns. The sampling system observed reproducible responses of soil gas concentrations to manipulations of soil nutrients and redox state, providing a new window into the microbial response to these key environmental forcings. Using site-specific N2O isotopologues as indicators of microbial processes, we constrain the dynamics of in situ microbial activity. Unlocking trace gas messengers of microbial activity will complement -omics approaches, challenge subsurface models, and improve understanding of soil heterogeneity to disentangle interactive processes in the subsurface biome.

scholarly journals Assessing the usefulness of acute physiological responses following resistance exercise: sensitivity, magnitude of change, and time course of measures

2019 ◽  
Vol 44 (3) ◽  
pp. 309-319 ◽  
Author(s):  
Joshua S. Jackman ◽  
Phillip G. Bell ◽  
Simone Gill ◽  
Ken van Someren ◽  
Gareth W. Davison ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Time Course ◽  
Signal To Noise Ratio ◽  
Physiological Responses ◽  
High Sensitivity ◽  
Maximal Voluntary Isometric Contraction ◽  
Reactive Protein ◽  
Adaptation Processes ◽  
Exercise Stimulus ◽  
Metalloproteinase 9

A variety of strategies exist to modulate the acute physiological responses following resistance exercise aimed at enhancing recovery and/or adaptation processes. To assess the true impact of these strategies, it is important to know the ability of different measures to detect meaningful change. We investigated the sensitivity of measures used to quantify acute physiological responses to resistance exercise and constructed a physiological profile to characterise the magnitude of change and the time course of these responses. Eight males accustomed to regular resistance exercise performed experimental sessions during a “control week”, void of an exercise stimulus. The following week, termed the “exercise week”, participants repeated this sequence of experimental sessions, and they also performed a bout of lower-limb resistance exercise following the baseline assessments. Assessments were conducted at baseline and at 2, 6, 24, 48, 72, and 96 h after the intervention. On the basis of the signal-to-noise ratio, the most sensitive measures were maximal voluntary isometric contraction, 20-m sprint, countermovement jump peak force, rate of force development (100–200 ms), muscle soreness, Daily Analysis Of Life Demands For Athletes part B, limb girth, matrix metalloproteinase-9, interleukin-6, creatine kinase, and high-sensitivity C-reactive protein with ratios >1.5. Clear changes in these measures following resistance exercise were determined via magnitude-based inferences. These findings highlight measures that can detect real changes in acute physiological responses following resistance exercise in trained individuals. Researchers investigating strategies to manipulate acute physiological responses for recovery and/or adaptation can use these measures, as well as the recommended sampling points, to be confident that their interventions are making a worthwhile impact.

A Mid-Infrared Dual-Comb Spectrometer for High Sensitivity Multi-Component Trace Gas Detection

2020 ◽  
Author(s):  
Leonard Nitzsche ◽  
Jens Goldschmidt ◽  
Jens Kießling ◽  
Sebastian Wolf ◽  
Frank Kühnemann ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Gas Detection ◽  
Trace Gas ◽  
Trace Gas Detection ◽  
Mid Infrared

Low-frequency multiplex CARS microscopy with a high-repetition near-infrared supercontinuum laser

2021 ◽  
Author(s):  
Yusuke Arashida ◽  
Atsushi Taninaka ◽  
Takayuki Ochiai ◽  
Hiroyuki Mogi ◽  
Shoji YOSHIDA ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
High Sensitivity ◽  
High Repetition ◽  
Spectrum Shaping ◽  
Crystal Phase Transition ◽  
Wavenumber Region ◽  
Anti Stokes

Abstract We have developed a multiplex Coherent anti-Stokes Raman scattering (CARS) microscope effective for low-wavenumber measurement by combining a high-repetition supercontinuum light source of 1064 nm and an infrared high-sensitivity InGaAs diode array. This system could observe the low-wavenumber region down to 55 cm-1 with high sensitivity. In addition, using spectrum shaping and spectrum modulation techniques, we simultaneously realized a wide bandwidth (<1800 cm-1), high wavenumber resolution (9 cm-1), high efficiency, and increasing signal to noise ratio by reducing the effect of the background shape in low-wavenumber region. Spatial variation of a sulfur crystal phase transition with metastable states was visualized.

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